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Adherence compounds in embryo transfer media for assisted reproductive technologies

  1. Stephan Bontekoe1,
  2. Neil Johnson2,
  3. Deborah Blake3,*

Editorial Group: Cochrane Menstrual Disorders and Subfertility Group

Published Online: 25 FEB 2014

Assessed as up-to-date: 13 NOV 2013

DOI: 10.1002/14651858.CD007421.pub3


How to Cite

Bontekoe S, Johnson N, Blake D. Adherence compounds in embryo transfer media for assisted reproductive technologies. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD007421. DOI: 10.1002/14651858.CD007421.pub3.

Author Information

  1. 1

    Academic Medical Centre, University of Amsterdam, Centre for Reproductive Medicine, Department of Obstetrics and Gynaecology, Amsterdam, Netherlands

  2. 2

    University of Adelaide, Robinson Research Institute, Adelaide, South Australia, Australia

  3. 3

    Repromed Fertility Specialists, Auckland, New Zealand

*Deborah Blake, Repromed Fertility Specialists, 105 Remuera Rd, Remuera, Auckland, 1050, New Zealand. dblake@repromed.co.nz. d.blake@xtra.co.nz.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 25 FEB 2014

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Characteristics of included studies [ordered by study ID]
Balaban 2004

MethodsParallel randomised controlled trial

Prospective recruitment of participants

Consecutive participant sampling

Single-centre trial at the VKV American Hospital in Istanbul, Turkey

Inclusion criterion: blastocyst-stage embryos

No exclusion criteria

No power calculation

Participants were allowed in the trial with multiple treatment cycles

Participants were enrolled for a period of four months, actual length of follow-up per participant was four weeks. It was intentionally kept short to reduce the chance of loss of participants, of which none occurred

An intention-to-treat analysis was performed


ParticipantsAge (years): treatment group 31.2, control group 31.6. No SD given

Primary or secondary subfertility: not reported

Causes of subfertility: 1. Male factor: treatment group 129, control group 121; 2. Unexplained subfertility: 35 treatments, 30 controls; 3. Endometriosis: three treatments, five controls, More than one factor: 26 treatments, 37 controls

Mean duration subfertility (years): treatment group 2.9, control group 3.2

Previous IVF and/or ICSI treatment (mean): treatment group 2.9, control group 3.2

All participants underwent ICSI. No IVF

No age analysis

386 blastocyst-stage transfers were recruited and randomly assigned: 193 to treatment group and 193 to control group. 405 embryos were transferred in treatment group and 424 in control group, resulting in a total of 829 transferred embryos. The total number of treatment cycles is unclear because participants were able to enrol multiple times. No loss, so the results of 386 participants were analysed


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus embryo transfer in G2.3 (0.125 mg/ml HA). All embryos were cultured in G-III series culture medium. Both culture and transfer media were manufactured by Vitrolife. EmbryoGlue was provided by the American Hospital of Istanbul

Randomisation on day of embryo transfer

Embryos in treatment group were exposed to EmbryoGlue for 30 minutes before transfer

Timing of embryo transfer: late in embryo development (day five)

Oocyte donation was unclear

All transferred embryos were fresh, no frozen-thaw protocol followed

Mean number of embryos transferred: treatment group 2.1, control group 2.1

Pregnancy determination: demonstration of gestational sac on ultrasound scan


OutcomesSecondary outcomes

  • Clinical pregnancy rate: defined as number of pregnancies demonstrated on ultrasound divided by group size
  • Multiple pregnancy rate: defined as number of twin pregnancies divided by number of pregnancies


Additional outcomes

  • Implantation rate: defined as number of demonstrated gestational sacs divided by total number of transferred embryos in group


NotesAbstract of ASRM conference presentation; no full article has been published regarding this trial

Additional data retrieved after study authors were contacted


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation into treatment or control group was performed using a computer-generated randomisation list

Allocation concealment (selection bias)Low riskRandomisation list was maintained by the chief embryologist, who did not participate in daily laboratory work. The embryologist preparing the transfer was given allocation information immediately before actual transfer

Blinding (performance bias and detection bias)
All outcomes
Low riskClinician and participant were blinded, the scientist was not

Incomplete outcome data (attrition bias)
All outcomes
High riskLive birth rate was not reported, actual length of follow-up was four weeks, which was done intentionally. Intention-to-treat analysis was performed, yet no loss of participants was reported

Selective reporting (reporting bias)Low riskOutcomes were prespecified in Materials and Methods section

Other biasLow riskEmbryoGlue was provided by the American Hospital. Transfer media used in both arms of the trial were comparable except for the addition of EmbryoGlue in the treatment arm. Multiple pregnancy rate was reported

Balaban 2011

MethodsSame as Urman 2008


ParticipantsSame as Urman 2008


InterventionsSame as Urman 2008


OutcomesLive birth rate: reported as the take-home baby rate and defined as the number of live births divided by the number of participants


NotesUpdate of live birth rate data resulting from clinical pregnancy rate was reported in Urman 2008, which did not use the live birth rate as an endpoint itself. No new inclusion of participants. Live births reported in the publication of Balaban 2011 will be extracted in this meta-analysis under Urman 2008

Conference proceeding at 27th Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Stockholm, Sweden


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskSame as Urman 2008. Participants were randomly assigned to treatment or control group using a computer-generated randomisation list

Allocation concealment (selection bias)Low riskSame as Urman 2008. Allocation to study arm was provided after opening of consecutively numbered, sealed opaque envelopes

Blinding (performance bias and detection bias)
All outcomes
Low riskSame as Urman 2008. Both clinician and participant were blinded to the group to which the participant was allocated

Incomplete outcome data (attrition bias)
All outcomes
Low riskLive birth rate was reported; follow-up was long enough, and data were analysed according to the intention-to-treat principle

Selective reporting (reporting bias)Low riskLive birth rate was reported in a prespecified manner

Other biasLow riskSame as Urman 2008

Ben-Rafael 1995

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant sampling

Multi-centre trial in the Hasharon Hospital of the Rabin Medical Center and in the Sackler School of Medicine of Tel Aviv University in Israel

Inclusion criteria: at least three embryos ready for transfer and no more than three previous treatment cycles

Exclusion criteria: fewer than three embryos ready for transfer

No power calculation was performed

Participants were included in the trial with only one treatment cycle

Participants were recruited over a period of six months

Length of follow-up per participant was until delivery

No intention-to-treat analysis was performed

Study was not supported by any commercial funding sources


ParticipantsAge (years): mean 34.2, SD 4.9

Patients were admitted for oocyte retrieval if two or more follicles of at least 18 mm mean diameter were present and the hormone profile was satisfactory

Not reported whether primary or secondary subfertility

Causes of subfertility were mechanical, male subfertility and combined causes. Duration of subfertility ranged from three to 21 years (mean 8.3 ± 6.9)

Previous IVF or ICSI was not reported, although participants could have had no more than three previous cycles

Participants underwent IVF

Age analysis: subgroups of < 31 years, 31 to 38 years and 39 to 42 years

211 patients who were admitted to the IVF unit were recruited for the trial, and all were randomly assigned: 101 to the treatment group and 110 to the control group. In total, 759 embryos were transferred: 368 in the treatment group and 391 in the control group. No participants were lost to follow-up, so 211 participants were analysed


InterventionsEmbryo transfer using a two-component fibrin sealant versus transfer in regular medium, consisting of EBSS-P-SR2 with 10 mg/ml human serum albumin, manufactured by MediCult. The fibrin sealant was made of two components. The first consisted of fibrinogen, fibronectin and an aprotinin solution. The second component consisted of thrombin and a calcium chloride solution The sealant was manufactured by Immuno AG

Randomisation was performed between fertilisation check and day of embryo transfer

Exposure time to fibrin sealant was not stated

Timing of transfer was early in embryo development, 48 to 50 hours after oocyte retrieval

Inclusion of oocyte donations was unclear

Unclear whether embryos were frozen-thawed or fresh

Two different culture and transfer medium brands: MediCult (culture medium and transfer medium control group) and Immuno AG (treatment group)

Mean number of embryos transferred: treatment group 3.64, control group 3.55

Method of pregnancy determination: demonstration of gestational sac on ultrasound scan


OutcomesSecondary outcomes

  • Clinical pregnancy rate: stated as percentage with number of transferred embryos as denominator
  • Adverse event rate: number of ectopic pregnancies, stated per participant


Additional outcomes

  • Implantation rate: stated as percentage of implantations from total number of embryos transferred


NotesAdditional data were retrieved after contact with the original investigators, although raw data such as numbers of multiple pregnancies and live births could no longer be retraced


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly divided into treatment and control groups, method of randomisation was not stated

Allocation concealment (selection bias)Unclear riskCentralised randomisation by lab technician, who decided who would go into treatment or control group, unclear how this decision was made

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth participant and doctor were blinded. Embryologist was not

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported, even though length of follow-up was until delivery. No intention-to-treat analysis was performed

Selective reporting (reporting bias)Unclear riskProposed results were not prespecified in Materials and Methods section

Other biasHigh riskNo commercial funding. Different transfer media brands were used in both arms of the trial. No multiple pregnancy rate was reported, although multiple embryos have been replaced in each treatment cycle

Chen 2001

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling unclear

Single-centre trial performed at the IVF-Unit of Dr Tsai and Dr Chen's Women Hospital in Chang-Hua, Taiwan

Inclusion criterion: patients undergoing IVF/ET who were having a day three embryo transfer

No exclusion criteria

Unclear whether a power calculation was performed

Participants were followed for 14 days after embryo transfer

Unclear whether participants were able to participate in multiple treatment cycles

Unclear whether intention-to-treat analysis was performed, but no mention was made of loss to follow-up. Length of follow-up was 14 days


ParticipantsMean age (range): treatment group 31.35 (22 to 43), control group 32.47 (23 to 40) years

Primary or secondary subfertility not reported

Cause and duration of subfertility not reported

Participants underwent IVF. Whether they had been through previous IVF treatments was not reported

No age analysis

70 participants were recruited and were randomly assigned to two groups: 35 to the treatment group and 35 to the control group. The exact number of embryos transferred is unclear. No loss of participants occurred, so the number of participants analysed was 70


InterventionsEmbryo transfer in basal XI HTF(=transfer medium) with 10% human serum albumin (HSA) and 0.125 mg/ml HA versus transfer in basal XI HTF with 10% HSA

Exposure time to HA before transfer was not stated

Timing of randomisation was unclear, but it most likely occurred on day of embryo transfer because of the inclusion criterion of day three transfers

Embryo transfer was performed early in embryo development (day three)

Frozen-thaw protocol unclear

Oocyte donation unclear

Culture and transfer medium brands not stated; however, medium appears to be similar between treatment and control groups, except for the addition of HA to treatment group

Mean number of embryos transferred (range): treatment group 2.71 (2 to 5), control group 3 (1 to 5)

Pregnancy was determined via a pregnancy test


OutcomesOther outcomes

  • Outcome measure of trial was biochemical pregnancy rate, but this was not part of the review


NotesAbstract of ESHRE conference presentation. Authors cannot be found to provide additional information


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly assigned to study or control group, but method of randomisation was unclear

Allocation concealment (selection bias)Unclear riskConcealment of participant's allocation was not clear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskNot stated in text

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live birth rate reported, length of follow-up was 14 days. Loss to follow-up is unclear, just as whether an intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskOutcome of biochemical pregnancy test was announced in Methods section

Other biasHigh riskCommercial funding source unclear. Transfer media used in both arms of the trial were comparable except for the addition of HA to the treatment arm. No multiple pregnancy rate was reported, and multiple embryos were replaced per cycle

Dittmann-Műller 2009

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant sampling

Multi-centre study performed at the IVF Unit of the Women's Hospital in Chemnitz, Germany, the IVF/ICSI Centre in Basel, Switzerland, and the Department of Obstetrics and Gynecology of the University Hospital in Würzburg, Germany

Inclusion criterion: undergoing IVF or ICSI between January 2006 and March 2007. No further inclusion criteria

No exclusion criteria

No power calculation was performed

Actual length of follow-up per participant was four weeks after embryo transfer. Participants were enrolled in the trial between January 2006 and March 2007 and could participate in only one treatment cycle

Study was commercially funded by Vitrolife

No intention-to-treat analysis was performed


ParticipantsMean age (SD): treatment group 33.4 (4.0), control group 33.6 (4.4) years

Primary or secondary subfertility not reported

Mean duration of subfertility was 4 ± 2.4 years. Indications for subfertility treatment were tubal factors (21.6%), andrologic factors (69.6%), cycle abnormalities (1%), others (12.7%) and idiopathic causes (17.6%). Some participants had multiple causes

Participants underwent both IVF and ICSI; most participants participated for the first time, but some were already in their third (or above) treatment cycle

No age analysis was performed

102 participants were recruited and were randomly assigned to a treatment group of 54 or a control group of 48. No loss of participants was reported, so the data on 102 participants were analysed. The exact number of embryos transferred is unclear


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G-2 (0.125 mg/ml HA). Embryos in both groups were cultured in G-1 and G-2 version 3 plus, supplemented with 10% recombinant human albumin

Randomisation was performed on the day before oocyte pick-up, which is between commencement of treatment and fertilisation check

Exposure time to EmbryoGlue (=higher concentration of HA) before transfer was 30 minutes

Transfer was performed early in embryo development, on day three

All transferred embryos were fresh

No oocyte donations were included in the trial

Both culture and transfer media were manufactured by Vitrolife

Mean number of embryos transferred (of both treatment and control groups) was 2.7

Pregnancy was determined by demonstration of gestational sac on ultrasound scan


OutcomesSecondary outcomes

  • Clinical pregnancy rate: reported as number of participants who got pregnant divided by group size
  • Multiple pregnancy rate: reported as number of participants pregnant with twins divided by number of participants from group who got pregnant


NotesTrial presented at ESHRE Conference. A full article is planned. Additional unpublished data received after contact with original investigators


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment or control group with the use of a cube. Even numbers formed the treatment arm, odd numbers the control arm

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was not reported

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth participants and clinician were blinded to treatment. Scientist was not

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported. Length of follow-up per participant was four weeks post ET. No intention-to-treat analysis was performed, yet no loss of participants was reported

Selective reporting (reporting bias)Low riskIn Materials and Methods section, it was announced that pregnancy rates will be recorded, and they are accounted for in the Results section

Other biasHigh riskTrial was commercially funded. Transfer media used in both arms of the trial were comparable except for the addition of EmbryoGlue to the treatment arm. Multiple pregnancy rate was reported

Fancsovits 2011

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant sampling

Single-centre study performed at the Semmelweis University School of Medicine in Budapest, Hungary

No strict inclusion or exclusion criteria

No power calculation was performed

Actual length of follow-up per participant was four weeks after embryo transfer. Participants were enrolled in the trial between January 2006 and March 2007 and could participate in only one treatment cycle

Study was commercially funded by Vitrolife

No intention-to-treat analysis was performed


ParticipantsMean age (SD): treatment group 35.7 (4.1), control group: 34.2 (4.6) years

Type, cause and duration of subfertility not reported

Number of previous IVF or ICSI treatments not reported

Included participants could undergo IVF or ICSI for the trial

An age analysis was performed; outcome data from participants 40 years of age or younger were compared with those from participants over 40 years of age

200 cycles were randomly assigned to a treatment group of 103 and a control group of 97. The total number of transferred embryos was 467: 238 in the treatment group and 229 in the control group


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G-2 (0.125 mg/ml HA). Embryos were incubated in EmbryoGlue or control medium for five to 10 minutes before transfer. Embryos in both groups were cultured in G-1 and G-2 until two to three days after fertilisation. The timing of the intervention was therefore early in embryo development. Randomisation was performed one day before embryo transfer. All culture and transfer media were manufactured by the same company—Vitrolife. All embryos were fresh, and oocyte donations were not included. The mean number of transferred embryos was 2.3 (± 0.8) in the treatment group and 2.4 (± 0.7) in the control group. Pregnancy was demonstrated via hCG pregnancy test and demonstration of a gestational sac on ultrasound


OutcomesPrimary outcomes

  • Live birth rate, reported as the number of born babies. Not reported in original publication


Secondary outcomes

  • Clinical pregnancy rate, reported as the number of clinical pregnancies, demonstrated by positive pregnancy test and on ultrasound, divided by the number of cycles. Reported as percentages in original publication, raw data after contact with authors


Additional outcomes

  • Implantation rate, defined as number of implantations divided by number of transferred embryos. Reported as percentages in original publication, raw data after contact with authors


NotesConference abstract of a trial presented at ESHRE meeting in 2011. Additional data and study information were provided by the original investigator after contact was made with the authors of this review. See Appendix 8

In this trial, cycles instead of participants were randomly assigned; this is not compatible with data analysis that is part of this systematic review because of the possibility of participants enrolling with multiple cycles. However, after contact was made with the original investigator, it appeared that the number of multiple entries was less than 10% of the total number (seven in the treatment group and 12 in the control group), which was deemed acceptable by the review authors


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandom allocation into treatment or control group, with randomisation achieved by a computer-generated randomisation table

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was not reported

Blinding (performance bias and detection bias)
All outcomes
Low riskBlinding of participant and clinician/nurse

Incomplete outcome data (attrition bias)
All outcomes
High riskFollow-up was long enough

Unclear whether any loss to follow-up occurred

No intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskOutcome measures were reported in a prespecified fashion. Of note, certain outcomes such as the live birth rate were not reported in the original publication but only after contact was made with the trial authors

Other biasHigh riskNo commercial funding

Culture media/environment in treatment and control groups comparable

Multiple pregnancy rate not reported whilst multiple embryo transfer policy was followed

Friedler 2005

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant sampling

Single-centre trial performed at the IVF and Infertility Unit of the Assaf Harofeh Medical Center of the University of Tel Aviv in Israel

Inclusion criteria: Participants had to be younger than 43 years, undergoing IVF/ICSI and failed to achieve pregnancy after four previous embryo transfers

Exclusion criteria: 43 years or older, more or fewer than four previous treatment cycles

Unclear whether a power calculation was performed

Actual length of follow-up was unclear, yet it appeared to be long enough for outcome measures to be reported

Participants were enrolled for only one treatment cycle (because of inclusion criterion of four previous attempts)

Unclear whether an intention-to-treat analysis was performed, neither whether was any loss to follow-up reported


ParticipantsMean age (SD): treatment group 33.8 (4.97), control 33.8 (4.97) years

Primary and/or secondary subfertility not reported

Cause and duration of subfertility not reported

Four previous IVF or ICSI treatments

Trials in which participants were undergoing both IVF and ICSI were included

No age analysis was performed

187 participants were recruited and randomly assigned to treatment group of 94 or control group of 93. No loss of participants was reported; therefore the data on 187 participants were analysed. Exact number of embryos transferred was unclear


InterventionsEmbryo transfer with EmbryoGlue (0.5 mg/ml HA) versus transfer with HTF medium enriched with 20% serum substitute supplement (SSS)

Timing of randomisation was unclear

Exposure time to HA before transfer was not stated

Transfer was performed early in embryo development (day two to four)

Unclear whether a frozen-thaw protocol was followed

Unclear whether oocyte donations were included

Transfer medium in treatment group was manufactured by Vitrolife; transfer medium for the control group was manufactured by Irvine Scientific

Mean number of embryos transferred: treatment group 3.4 ± 1.05, control group 3.2 ± 1.05

Method of pregnancy determination was not reported


OutcomesSecondary outcomes

  • Clinical pregnancy rates: unclear whether defined per participant or per embryo transferred, but it can be assumed to be per participant
  • Adverse event rate: Miscarriage rate was measured. Not clear whether per participant, per clinical pregnancy or per embryo transferred. However, a notably high early spontaneous abortion rate was observed in both groups


Additional outcomes

  • Implantation rate: definition unclear


NotesAbstract of an ESHRE conference presentation


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly allocated to treatment or control group, but method of randomisation was unclear

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding was not reported

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported, actual length of follow-up per participant was unclear, participant loss and intention-to-treat analysis were unclear

Selective reporting (reporting bias)Low riskOutcome measures were reported in a prespecified way

Other biasHigh riskCommercial funding source was unclear. Transfer media of treatment and control groups were made by different manufacturers. No multiple pregnancy rate was reported, and multiple embryos were transferred per cycle

Friedler 2007

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant sampling

Single-centre trial performed at the IVF and Infertility Unit of the Assaf Harofeh Medical Center, Sackler School of Medicine, University of Tel Aviv, Israel

Inclusion criteria: patients who failed to achieve an ongoing pregnancy after more than four previous embryo transfers, during which two to four embryos were transferred each time, including at least one optimal embryo. Had to be younger than 43 years of age and had to have given informed consent. Undergoing ICSI at the IVF Unit

Exclusion criteria: patients older than 43 years of age, suffering from a systemic disease, BMI > 29 kg/m2, uterine malformation, evidence of low ovarian response, elevated baseline FSH (> 12 IU/L), hydrosalpinx or participation in any other clinical study

Power calculation performed but not followed. Group size of 112 in each arm of the study was proposed, but after an interim analysis of 101 participants, the trial was stopped. This was done for ethical reasons, and the study is therefore eligible

Participants were enrolled in the trial from June 2005 to November 2006. Actual length of follow-up per participant was up to nine months. However, one of the outcome measures of the study was delivered or ongoing pregnancy rate

Participants were able to enrol in the study with only one single cycle

An intention-to-treat analysis was not performed

Study was free from commercial funding


ParticipantsMean age (SD): treatment group 33.1 (5.1), control group 31.7 (5.6) years

Not reported whether study concerned primary or secondary subfertility

Causes of subfertility included male factor, tubal factor, endometriosis, unexplained subfertility and combination of female and male factors

Duration of subfertility was not reported

Participants had to have undergone at least four previous treatment cycles. Average was 5.5 previous unsuccessful embryo transfers

All participants underwent ICSI

No age analysis was performed

101 participants were recruited and randomly assigned to a treatment group of 51 or a control group of 50. 159 embryos were transferred in the treatment group and 146 in the control group, resulting in a total of 305 embryos transferred. No participants were excluded, withdrawn or lost to follow-up, so data on 101 participants were analysed


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA and 2.5 mg/ml recombinant human albumin) versus transfer in human tubal fluid (HTF) with gentamycin, enriched with 20% serum substitute supplement

Randomisation on day of embryo transfer

Exposure time to HA before embryo transfer was 10 minutes

Transfer was performed early in embryo development (days two and three)

No frozen-thaw protocol was followed

Unclear whether oocyte donations were included

Transfer media of treatment and control groups were manufactured by two different companies: treatment medium by Vitrolife and control medium by Irvine Scientific

Mean number of embryos transferred: treatment group 3.1 ± 0.73, control group 2.9 ± 0.63

Pregnancy was determined by demonstration of gestational sac on ultrasound scan and pregnancy test


OutcomesSecondary outcomes

  • Ongoing pregnancy rate: defined as delivered or ongoing pregnancies divided by number of participants per group
  • Clinical pregnancy rate: defined by ultrasound scan, number of pregnancies divided by group size
  • Multiple pregnancy rate: defined as number of multiple pregnancies divided by number of pregnancies in group
  • Adverse event rate: Both ectopic pregnancy rate and early spontaneous abortion rate have been reported. Defined as number of events divided by group size. For this review, the data for both types of adverse events have been added up


Additional outcomes

  • Implantation rate: defined as number of implantations per embryo transferred in group


NotesNo overlap in participants with Friedler 2005

Additional data retrieved after contact was made with study authors


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment or control group based on computer-generated random number sequence

Allocation concealment (selection bias)Low riskParticipant allocation was performed by the chief embryologist just before embryo transfer, according to a computer-generated random number sequence

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth participant and clinician were blinded. The embryologist was not blinded

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported, even though the actual length of follow-up per participant was up to nine months. No loss of participants, therefore not accounted for. No intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskClinical pregnancy rate was announced in the Methods section. However, many other outcomes were reported in the Results section

Other biasUnclear riskFree from commercial funding. Embryos in treatment and control groups were transferred in media from different manufacturers, and similarity between culture media was unclear. Multiple pregnancy rate was reported

Hazlett 2004

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling in a non-consecutive order

Single-centre trial performed at the Department of Embryology of Karande and Associates in Hoffman Estates, Illinois, USA

No inclusion or exclusion criteria

Power calculation was performed

Length of follow-up per participant was four to six weeks post–positive hCG test. No intention-to-treat analysis was performed

It is unclear whether participants were able to enrol in multiple treatment cycles in this trial, but because they were included in the bigger trial that followed this trial, it can be assumed that this also occurred in the current trial


ParticipantsMean age (SD): treatment group 34.0 (4.5), control group 33.1 (5.1) years

Causes, duration and whether primary or secondary subfertility not reported

Whether participants have undergone previous IVF/ICSI treatments was unclear

Included participants underwent both IVF and ICSI

94 participants were recruited for this trial and were randomly assigned to a treatment group of 46 or a control group of 48. No loss of participants occurred, so the data on 94 participants have been analysed

266 embryos were transferred in the treatment group and 253 in the control group, resulting in a total of 519 transferred embryos. These data were retrieved after the original authors were contacted. However, these numbers are not comparable with the mean numbers given in the abstract, which states that a mean number of 2.4 ± 0.8 embryos were transferred in the treatment group. These numbers reflect the number of embryos transferred in the study that followed from this trial (Hazlett 2008)


InterventionsEmbryo transfer on day three and day five of embryo development in EmbryoGlue (0.5 mg/ml HA) versus transfer in IVC-1 on day three and transfer in G2.3 (0.125 mg/ml HA) on day five Embryos were cultured in IVC-1 up to day three and in G2.3 from day three to day five

Randomisation was performed from fertilisation check to embryo transfer, but it is unclear whether it occurred on the day of embryo transfer itself

Exposure time to EmbryoGlue before transfer was 10 to 60 minutes

No frozen-thaw protocol was followed

Only the participants' own oocytes were fertilised, so no donor oocytes were included

The manufacturers of the culture and transfer media were In Vitro Care and Vitrolife

Mean number of embryos transferred: treatment group 2.4 ± 0.8, control group 2.4 ± 0.9

Methods of pregnancy determination: hCG pregnancy test and sonogram to determine gestational sac and fetal heartbeat


OutcomesSecondary outcomes

  • Clinical pregnancy rate: defined by gestational sac and fetal heartbeat on sonogram, four to six weeks post–positive hCG test. Stated as percentage in abstract, unclear of what.


Additional outcomes

  • Implantation rate: stated as percentage in abstract, unclear of what


Other outcomes

  • Viable pregnancy rate: defined as ongoing pregnancy rate


NotesAbstract from ESHRE conference presentation

Data from this trial have been incorporated in a bigger trial (Hazlett 2008); therefore outcome data will be extracted only from Hazlett 2008

Additional data retrieved after study authors were contacted


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation to treatment or control group based on computerised allocation system, information retrieved after contact with authors

Allocation concealment (selection bias)Low riskComputerised allocation

Blinding (performance bias and detection bias)
All outcomes
Low riskParticipant, clinician/nurse and embryologist were all blinded

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo live births were reported, no intention-to-treat analysis was performed. However, no loss of participants was reported. Live births were retrieved after contact with study author regarding Hazlett 2008

Selective reporting (reporting bias)Low riskOutcomes were reported in a prespecified way

Other biasHigh riskTrial was free of commercial funding. Data for the day three and day five control groups are not comparable because transfers were performed in media of different media brands. No multiple pregnancy rates were reported, and multiple embryos were transferred per cycle

Hazlett 2005

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling non-consecutive

Single-centre study performed at Karande and Associates in Hoffman Estates, Illinois, USA

Non-donor, normal and low-responding IVF patients were included in the study

Power calculation was performed, which estimated that a 20% difference in clinical pregnancy rate would be found, with 5% significance and 80% power if at least 107 participants were included in each arm of the study

Length of follow-up appears to be nine weeks of gestation

Participants were able to partake in multiple treatment cycles in case of treatment failure

Intention-to-treat analysis was not performed


ParticipantsMean age: treatment group 32.4, control group 33.3 years

Cause, duration and primary or secondary subfertility not reported

Included participants were undergoing IVF or ICSI. Unclear whether participants had undergone previous treatments

No age analysis was reported. Participants were divided into groups of normal and low responders, based on concentration of gonadotrophin received daily by participants

223 participants were randomly assigned to a treatment group of 116 and a control group of 107. The treatment group was divided into 84 participants who had a day three transfer and 32 participants who had a day five transfer. The control group comprised 78 day three transfers and 29 day five transfers

The total number of transferred embryos was 519: 266 in the treatment group and 253 in the control group

Participant data were clarified by contacting study author


InterventionsEmbryo transfers on day three or day five of development in EmbryoGlue (0.5 mg/ml HA) versus transfer in IVC-1 or IVC-2 plus 0.5% HSA (human serum albumin) on day three and G2.3 plus 0.5% HSA on day 5

Embryos were cultured in IVC-1 or IVC-2 until day three, and in G2.3 plus 0.5% HSA until day five

Randomisation took place on the day before transfer

Embryos in the treatment group were exposed to EmbryoGlue for 10 to 60 minutes before transfer

Unclear whether all embryos were fresh or frozen-thawed

Oocyte donations were not included

Culture and transfer media were manufactured by different companies: In Vitro Care and Vitrolife

Mean number of embryos transferred not provided in printed text

Pregnancy determination by hCG pregnancy test and demonstration of gestational sac and fetal heartbeat on ultrasound scan


OutcomesPrimary outcomes

  • Live birth rate: data retrieved after contact with author. Number of live births per number of participants


Secondary outcomes

  • Clinical pregnancy rate: defined as participants with at least one intrauterine gestational sac present four weeks post–positive hCG


Additional outcomes

  • Implantation rate: defined as number of intrauterine gestational sacs divided by total number of embryos transferred


Other outcomes

  • Viable pregnancy rate: defined as ongoing pregnancy rate


NotesAbstract of ASRM conference presentation

Data from this trial were also published in the study Hazlett 2008; therefore, outcome data will be extracted only from Hazlett 2008

Additional data were retrieved by contacting study authors


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment and control groups by computer-generated randomisation

Allocation concealment (selection bias)Low riskComputerised allocation with sealed envelopes

Blinding (performance bias and detection bias)
All outcomes
Low riskParticipants and clinicians were blinded. Scientist were not

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskLength of follow-up appears to be nine weeks, and no intention-to-treat analysis was stated. No loss was accounted for. Live births were retrieved by contacting study author regarding Hazlett 2008

Selective reporting (reporting bias)Low riskOutcomes were reported in a prespecified way

Other biasHigh riskNo commercial funding source. Embryos in treatment and control groups were transferred in media from different brands, even within the control group. Embryo transfer policy was unreadable; therefore, no conclusions can be made about the multiple pregnancy rate

Hazlett 2008

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling in consecutive order but stated as non-consecutive in Hazlett 2005

Single-centre trial performed at the Department of Embryology of Karande and Associates in Hoffman Estates, Illinois, USA

Patients who were excluded were diagnosed as having a low success rate, which meant having a diminished ovarian reserve (FSH of at least 10 IU/ml), being older than 40 years of age or having a hydrosalpinx

Participants were selected for a day five embryo transfer if a minimum of five embryos with little fragmentation were present on day three and/or if they had eight or more fertilised zygotes

A power calculation was performed, which estimated that a 20% difference in clinical pregnancy rate would be found, with 5% significance and 80% power if at least 107 participants were included in each arm of the study

Length of follow-up per participant was 11 weeks

No intention-to-treat analysis was performed

Participants were able to enrol in the study with multiple treatment cycles in case of treatment failure


ParticipantsMean age (SD): Participants were divided into day three and day five transfer subgroups. Treatment groups: day three, 33.4 (4.4), day five, 31.4 (4.2) years; control groups: day three, 33.4 (5.0), day five, 33.1 (4.8) years

Causes and duration of subfertility not reported. Nor was it reported whether study concerned primary or secondary subfertility. Yet text states that there were no differences between treatment and control groups regarding cause and duration

Included participants underwent IVF or ICSI. Unclear whether they underwent previous treatments

No age analysis

233 participants appear to be recruited, even though only 224 were stated in the text. Of 233 participants, 223 were randomly assigned to a treatment group of 116 or a control group of 107 Five participants were part of a preliminary study and were not randomly assigned. Five others were withdrawn for protocol violations. The treatment group was divided into 84 participants who had a day three transfer and 32 who had a day five transfer. The control group comprised 78 day three transfers and 29 day five transfers

The total number of transferred embryos was 519: 266 in the treatment group and 253 in the control group


InterventionsEmbryo transfer on day three or day five of development in EmbryoGlue (0.5 mg/ml HA) versus transfer in IVC-1 or IVC-2 + 0.5% HSA (human serum albumin) on day three or G2.3 (0.125 mg/ml HA) + 0.5% HSA on day five. Therefore, for data analysis, this trial is divided into day three transfers, which compare HA versus no HA, and day five transfers, which compare HA versus low concentrations of HA

Embryos were cultured in IVC-1 or IVC-2 until day three and in G2.3 for the additional two days

Timing of randomisation was unclear. It appears that it occurred on the day before embryo transfer, for it is stated this was in the trial Hazlett 2005, which comprises data on the same participants

Exposure time to EmbryoGlue in the treatment group was 10 to 60 minutes before embryo transfer

No frozen-thaw protocol was followed

No donor oocytes were included

Transfer and culture media were manufactured by two different manufacturers: In Vitro Care and Vitrolife

Mean number of transferred embryos: treatment group day three: 2.5 ± 0.9, day five: 2.1 ± 0.5; control group day three: 2.4 ± 0.8, day five: 2.1 ± 0.9

Pregnancy was determined via pregnancy tests and demonstration of gestational sac and fetal heartbeat on ultrasound scan


OutcomesPrimary outcomes

  • Live birth rate: data received after contact with author regarding other publication of the same data (Hazlett 2005); reported for the whole study population and for day three and day five transfers separately. Defined as number of live births divided by number of participants


Secondary outcomes

  • Clinical pregnancy rate: defined as number of participants with at least one intrauterine gestational sac on ultrasound two weeks after positive hCG pregnancy test divided by total number of participants


Additional outcomes

  • Implantation rate: defined as total number of intrauterine gestational sacs divided by total number of embryos transferred


Other outcomes

  • Viable pregnancy rate: defined as ongoing pregnancy demonstrated by fetal cardiac activity at seven weeks of gestation divided by group size


NotesThis study comprises data from previous publications (Hazlett 2004 and Hazlett 2005), but only outcome data have been extracted from it

Additional data were retrieved by contacting study authors


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment or control groups by a computer-generated random numbers sequence

Allocation concealment (selection bias)Low riskRandomisation was performed by computer-generated random numbers sequence using sealed envelopes to allocate to the treatment arm

Blinding (performance bias and detection bias)
All outcomes
Low riskParticipant and clinician/nurse were blinded. Embryologist was not

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskLive births were reported after contact with study author. No intention-to-treat analysis was performed. Loss to follow-up was accounted for. Actual length of follow-up per participant in published study was 11 weeks; live birth data were retrieved later on

Selective reporting (reporting bias)Low riskClinical pregnancy rate and implantation rate were reported in a prespecified way

Other biasHigh riskFree from commercial funding. Different media brands were used, therefore not comparable. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

Khan 2004

MethodsParallel randomised controlled trial

Prospective participant recruitment

Sampling unclear

Single-centre trial performed at IVF Michigan in Rochester Hills in the USA

Participants with all types of subfertility diagnosis were included, but they had to be younger than 39 years of age

Unclear whether a power calculation was performed

Length of follow-up per participant is unclear

Unclear whether an intention-to-treat analysis was performed, or whether any loss to follow-up occurred

Unclear whether participants were able to enrol in the trial on multiple treatment cycles


ParticipantsMean age (range): treatment group 32.7 (24 to 39), control group 33.8 (23 to 39) years

Causes and duration of subfertility not specified. Nor was it stated whether study concerned primary or secondary subfertility

Unclear whether participants underwent IVF or ICSI or both, and whether they had received previous treatments

No age analysis was performed

165 participants were recruited for this trial and were randomly assigned to treatment and control groups. No mention in text of group sizes, nor of any loss to follow-up or numbers of embryos transferred. Study authors were contacted, but no response has been received yet


InterventionsEmbryo transfer in EmbryoGlue (0.5% mg/ml HA) versus transfer in P1 Complete Medium (contains gentamycin, taurine and 10% protein supplement; no HA)

All embryos were cultured in P1 Complete Medium

Timing of randomisation was unclear

Embryos in treatment group were exposed to EmbryoGlue for approximately 10 minutes before transfer

Transfers were performed early in embryo development (day three)

Unclear whether frozen-thawed embryos were included in the trial

Unclear whether donor oocytes were included

All embryos were cultured in medium manufactured by Irvine Scientific, and control group was transferred in same medium; treatment group was transferred in EmbryoGlue manufactured by Vitrolife

Mean number of embryos transferred: treatment group 3.3, control group 3.1

Method of pregnancy determination was not reported


OutcomesSecondary outcomes

  • Ongoing pregnancy rate: no definition given in the text, only percentages given; no raw data


Additional outcomes

  • Implantation rate: no definition given in the text, only percentages given; no raw data


NotesAbstract of an ESHRE conference presentation


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly assigned to treatment or control group, but method of randomisation was not reported

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskUnclear whether participants, clinicians and/or embryologists were blinded

Incomplete outcome data (attrition bias)
All outcomes
High riskLength of follow-up unclear. No live births reported. No information on actual participant numbers or loss. No intention-to-treat analysis reported

Selective reporting (reporting bias)Low riskOngoing pregnancy and implantation rate were reported in a prespecified way

Other biasHigh riskCommercial funding source was unclear. Different transfer media brands were used. However, culture and transfer media for both arms were comparable, with the exception of EmbryoGlue added to the medium in the treatment arm. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

Korošec 2007

MethodsParallel randomised controlled trial

Prospective participant recruitment and consecutive sampling

Multi-centre trial performed at the Department of Obstetrics and Gynecology of the University Medical Centre of Ljubljana, Slovenia, and at the Institute for Reproductive Medicine and Endocrinology in Bregenz, Austria

Inclusion criteria: Women had to be younger than 37 years of age and within their first three treatment cycles, resulting in selection of twin-prone women

A power calculation that estimated 80% power was performed according to preliminary results before the entire study population was randomly assigned

Length of follow-up per participant was 30 days. However, a subgroup of participants undergoing a fresh embryo transfer was checked for live births a year later. These data have not been published

No intention-to-treat analysis was performed

Participants were able to enrol in the study with multiple cycles


Participants328 women were recruited for this study; it included a group of women who had received a single fresh embryo transfer and a group who had received a single frozen-thawed embryo transfer. Participants were randomly assigned to a treatment group of 138 and a control group of 158. 32 women declined participation after randomisation was carried out. Because only a single embryo was transferred per woman, 296 (138 + 158) transfers were performed and analysed. The tables in the Results section of the article present only the data on 279 transfers, but in the text, the data on 17 women who had received a compulsory single transfer were reported

Mean age (SD): treatment group fresh 31.3 (3.7), frozen-thawed 32.1 (3.5); control group fresh 31.9 (3.7), frozen-thawed 32.7 (3.2)

Causes of subfertility included tubal factor, endometriosis, endocrine disorders, idiopathic causes, male factors, combined female factors and combined female and male factors

Duration of subfertility was not reported, nor whether primary and/or secondary subfertility was present

Included women underwent IVF or ICSI and could have received up to two previous treatments

No age analysis was performed


InterventionsFresh and frozen-thawed embryo transfers in EmbryoGlue (0.5 mg/ml HA) versus fresh and frozen-thawed transfers in M2 medium

Embryos were cultured to the blastocyst stage sequentially in M1 and M2 culture medium, which contains no HA

Randomisation was performed on the day of embryo transfer

Embryos in the treatment group were exposed to HA for at least four hours

Transfers were performed in the blastocyst stage of embryo development, which occurs on day five

Donor oocyte inclusion was unclear

Culture and transfer media were manufactured by MediCult and Vitrolife

Only one embryo was transferred per cycle

Pregnancy was determined by hCG pregnancy test, and gestational sacs and fetal heartbeat were demonstrated on ultrasound scan


OutcomesPrimary outcomes

  • Live birth rate: Live birth rate was retrieved after the study author was contacted; it was measured only in the fresh embryo transfer group and was reported as a percentage of the number of clinical pregnancies


Secondary outcomes

  • Clinical pregnancy rate: defined by ultrasound observation of a positive heartbeat 30 days after embryo transfer. Reported as a percentage of the number of transfers
  • Adverse event rate: concerns miscarriage rate. Data were retrieved by contacting study author and were reported only in the fresh embryo transfer group. They were reported as a percentage of the number of clinical pregnancies


Other outcomes

  • Pregnancy rate in cycles after previous implantation failure


NotesAdditional data were retrieved by contacting study authors. Important note: Only single embryos were transferred, and no multiple pregnancies occurred


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to a treatment or control group by a computerised randomisation table

Allocation concealment (selection bias)High riskAllocation was performed at the site by the investigator just before the intervention was provided, according to the computerised randomisation table. Information was retrieved by contacting the study author

Blinding (performance bias and detection bias)
All outcomes
Low riskClinician and participants were blinded, the scientist was not

Incomplete outcome data (attrition bias)
All outcomes
High riskLive birth rate was reported when original investigators were contacted, but it was not recorded for the entire study group. Loss to follow-up was accounted for, but no intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskClinical pregnancy rates were reported in a prespecified way. Live birth rate was retrieved by study author contact

Other biasLow riskThe trial was free from commercial funding. Different transfer media brands were used in treatment and control groups, but culture media were comparable up to the moment of embryo transfer. No multiple pregnancy rate was reported, but only singleton embryo transfers

Mahani 2007

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling unclear

Multi-centre trial performed at the Department of Obstetrics and Gynaecology of the Afzallipour Hospital, Kerman University of Medical Sciences, in Kerman, Iran, and the Research and Clinical Centre for Infertility of the Sadoughi University of Medical Sciences in Yazd, Iran

Inclusion criteria: 35 years of age or younger, at least three embryos suitable for transfer and no previous IVF/ICSI cycles

Unclear whether a power calculation was performed

Participants were included from September 2003 to January 2004, length of follow-up per participant appears to be 10 weeks

Unclear whether participants could enrol with multiple treatment cycles

Unclear whether an intention-to-treat analysis was performed; no mention of loss to follow-up


Participants60 women were recruited and randomly assigned to a treatment group of 30 and a control group of 30. No loss of participants was reported, so data on all 60 women were analysed. 183 embryos were transferred: 85 in the treatment group and 98 in the control group

Mean age (SD): treatment group 27.5 (4.26), control group 28.6 (3.68) years

Causes of subfertility and whether it concerned primary or secondary subfertility not reported

Mean duration of subfertility was 7.24 (3.68) years in treatment group and 6.93 (3.6) years in control group

Both IVF and ICSI participants were included, but they could not have received previous treatment

No age analysis was performed


InterventionsEmbryo transfers in EmbryoGlue (0.5 mg/ml HA) versus transfers in standard medium containing 20% albumin

Culture medium was not stated

Randomisation occurred on day of embryo transfer

Embryos in treatment group were exposed to HA for 10 minutes before transfer

Transfer was performed on day three of embryo development

All embryos were fresh, no frozen-thaw protocol was followed

Donor oocyte inclusion was unclear

Transfer medium from treatment group was manufactured by Vitrolife, transfer medium from control group by Bayer Corporation

Mean number of embryos transferred (SD): treatment group 2.68 (0.66), control group 2.7 (0.79)

Pregnancy demonstrated by hCG pregnancy test 14 days after transfer; gestational sac and fetal viability were demonstrated on ultrasound scan


OutcomesSecondary outcomes

  • Clinical pregnancy rate: defined as number of demonstrated pregnancies divided by number of implantations
  • Adverse events rate: defined as number of miscarriages divided by number of implantations


Additional outcomes

  • Implantation rate: defined as number of demonstrated gestational sacs divided by number of participants


NotesArticle was translated by Interlibrary Loans and Document Delivery


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly assigned to treatment or control group. However, method of randomisation was unclear

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was not stated

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth clinician and participant were blinded to treatment. The scientist was not

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported. No intention-to-treat analysis nor loss of participants was reported. Length of follow-up appears to be 10 weeks

Selective reporting (reporting bias)Low riskClinical pregnancy and implantation rates were reported in a prespecified way. Miscarriage was not announced but was added to the Results section

Other biasHigh riskCommercial funding source was unclear. Different transfer media brands were used for both study groups. However, it was unclear whether two different transfer media were used, or if EmbryoGlue was added to the same transfer medium used in the control group. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

Morbeck 2007

MethodsParallel randomised controlled trial

Prospective participant recruitment

Consecutive participant group sampling

Single-centre trial performed at the Mayo Clinic in Rochester, Minnesota, USA

Inclusion criteria: frozen-thawed embryo transfers; men over the age of 18 years and women from 18 to 42 years (if using their own oocytes and embryos frozen before 39 completed years) or from 18 to 50 years (if using donor oocytes)

Exclusion criteria: participation in prior study. Blastocyst transfers. Single embryo transfers for medical reasons. Prior embryo transfer with large amount of blood on outside of the catheter. Three or more previous treatment failures

A power calculation was performed; no further information

Participants were enrolled in the study from May 2003 to June 2005. Length of follow-up per participant was up to time of delivery

Unclear whether an intention-to-treat analysis was performed

Participants were allowed in the study with only one treatment cycle


Participants150 participants were scheduled to enrol in the trial, but only 121 were recruited. Of these, 38 were excluded (reasons unknown), resulting in 83 participants randomly assigned to a treatment group of 41 and a control group of 42. 92 embryos were transferred per group, resulting in a total of 184 embryos transferred

Participant mean age (SD): treatment group 31.4 (3.8), control group 30.5 (4.2) years

Causes, duration and kind of subfertility not reported

Participants could not have received more than two previous treatment failures, but no further information on previous IVF/ICSI treatments was provided

All participants appeared to undergo IVF; ICSI was not stated

Age analysis: two sets: participants < 35 years versus ≥ 35 years, both in blocks of four


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G2 culture medium (0.125 mg/ml HA). All embryos were cultured in G2 culture medium

Randomisation was performed before commencement of the treatment cycle

Treatment group was exposed to EmbryoGlue for an average of 15 minutes before transfer, with a range of 6 to 44 minutes (one transfer 62 minutes and another 131 minutes)

Transfer was performed early in embryo development (day three)

All embryos were frozen-thawed

Donor oocytes were included, but outcomes were not reported as a comparison between donor oocytes and non-donor oocytes

Culture and transfer media for both groups were manufactured by Vitrolife

Mean number of transferred embryos per participant was 2.2 in both treatment and control groups (numbers calculated from unpublished data provided by the study author)

Pregnancy was determined by fetal heartbeat monitoring and demonstration of gestational sac on ultrasound scan


OutcomesPrimary outcomes

  • Live birth rate: number of deliveries divided by number of treatment cycles. Data on both donor oocytes and non-donor oocytes were reported and were retrieved by contacting the study author


Secondary outcomes

  • Ongoing pregnancy rate: number of ongoing pregnancies demonstrated by fetal heartbeat monitoring per participant
  • Clinical pregnancy rate: number of pregnancies demonstrated by gestational sac on ultrasound per participant


Additional outcomes

  • Implantation rate: number of gestational sacs demonstrated on ultrasound divided by number of embryos transferred


NotesFrom ClinicalTrial.gov

This study was suspended because the implantation rate was significantly lower in the treatment group than in the control group. Outcome data originally were not published but were received by contacting the principal investigator


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment or control groups by a random numbers table

Allocation concealment (selection bias)Low riskAllocation concealment was performed with sealed, opaque, numbered envelopes

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth participant and clinician were blinded to treatment. The scientist was not

Incomplete outcome data (attrition bias)
All outcomes
Low riskLive births were reported. Length of follow-up was up to time of delivery. Outcomes originally were not reported because the study was suspended, but data were retrieved by contacting the original investigators. Unclear whether an intention-to-treat analysis was performed. No loss to follow-up was apparent, apart from the 38 participants who were excluded, so loss of participants is accounted for

Selective reporting (reporting bias)Low riskClinical pregnancy and implantation rates were prespecified. Ongoing pregnancy rate was reported when the original study author was contacted

Other biasHigh riskTrial was funded by and was performed at the Mayo Clinic, but this is not considered to be commercial funding. Transfer media in both study groups were comparable, with the exception of EmbryoGlue added to the medium in the treatment group. Multiple pregnancy was not reported, although multiple embryos were transferred per cycle

Ravhon 2005

MethodsParallel randomised controlled trial

Prospective participant recruitment

Participant sampling unclear

Single-centre trial performed at the Edith Wolfson Medical Center in Holon, Israel

Only fresh embryo transfers were included in the study

Unclear whether a power calculation was performed

Participants were enrolled in the study between July 2004 and November 2004, but the actual length of follow-up was not reported

An intention-to-treat analysis was not mentioned in the text, so unclear whether it was performed

Unclear whether multiple treatment cycles per participant were included in the study


Participants148 participants were recruited and randomly assigned to a treatment group of 79 or a control group of 69. No loss to follow-up was apparent, so the data on all 148 participants were analysed

The number of embryos transferred was unclear, for only mean numbers per participant were given

Mean age (SD): treatment group 34.8 (5.8), control group 34.3 (5.9) years

Causes of subfertility and whether it concerned primary or secondary subfertility not reported

Subfertility duration (SD): treatment group 3.9 (4.9) years, control group 3.6 (2.8) years

All participants underwent IVF

Number of previous cycles (SD): treatment group 4.5 (4.1), control group 5.4 (4.9)

No age analysis was performed


InterventionsFresh embryo transfers in EmbryoGlue (0.5 mg/ml HA) versus fresh transfers in G1 medium (0.125 mg/ml HA)

All embryos were cultured in G1 medium

Randomisation was performed on day of embryo transfer

Exposure time to EmbryoGlue before transfer was not reported

Timing of transfer during embryo development was not reported

All embryos were fresh, no frozen-thaw protocol was followed

Inclusion of donor oocytes was unclear

Culture and transfer media were manufactured by Vitrolife

Mean number of embryos transferred per participant: treatment group 2.3 ± 0.8, control group 2.2 ± 0.8

Method of pregnancy determination was not reported


OutcomesSecondary outcomes

  • Clinical pregnancy rate: reported as a percentage of group size. No further definitions given


Additional outcomes

  • Implantation rate: reported as a percentage, but total number of embryos transferred was unclear, so implantation rate cannot be calculated. No further definitions


NotesAbstract of a ASRM conference presentation.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly allocated to a treatment or a control group, but method of randomisation was unclear

Allocation concealment (selection bias)Unclear riskAllocation concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskUnclear whether participants, clinicians and/or scientists were blinded

Incomplete outcome data (attrition bias)
All outcomes
High riskActual length of follow-up was unclear. No live births were reported. Loss to follow-up was not accounted for, and it was unclear whether an intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskClinical pregnancy and implantation rates were reported in a prespecified way

Other biasHigh riskNo commercial funding. Same transfer media brand in treatment and control groups. Transfer media were comparable, with the addition of EmbryoGlue to the treatment group. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

Schoolcraft 2002

MethodsParallel randomised controlled trial

Prospective participant recruitment

Method of sampling of participants was unclear

Single-centre trial performed at the Colorado Center for Reproductive Medicine in Englewood, Colorado, USA

Both IVF patients with their own oocytes and oocyte donors were included

Unclear whether a power calculation was performed

Participants were enrolled in this trial from January 2001 to February 2002. The exact length of follow-up per participant was not stated, but it was long enough to permit measurement of the trial's proposed outcomes

Unclear whether an intention-to-treat analysis was performed

Unclear whether multiple treatment cycles or only one treatment cycle per participant were included in the trial

Trial was supported by Vitrolife


ParticipantsA total of 175 IVF participants and oocyte donors were recruited for this trial. 141 of them were IVF patients, and 34 were oocyte donors. 91 participants were randomly assigned to the treatment group and 84 to the control group. No loss was reported, so the data on all 175 participants were analysed. Number of transferred embryos was unclear; only the mean number per group was published

Age: not reported

Not reported whether study concerned primary and/or secondary subfertility

Cause and duration of subfertility not reported

Trial studied only IVF participants, no participants receiving ICSI. Not reported whether participants had received previous IVF treatment

No age analysis was reported


InterventionsEmbryo transfer of participants' own or donated fertilised oocytes in G2.3 medium supplemented with EmbryoGlue (0.5 mg/ml HA) versus transfer in G2.3 medium (0.125 mg/ml HA)

All embryos were cultured in G1.3 medium

Timing of randomisation was unclear

Embryos were exposed to the higher concentration of HA just before transfer

Transfer was performed on day three of embryo development

Donor oocytes were included

Unclear whether embryos had to be fresh or if frozen-thawed embryos were also included

All culture and transfer media were manufactured by Vitrolife

Mean number of embryos transferred: treatment IVF group 3.9, treatment donor oocytes 3.9; control IVF group 3.3, control donor oocytes 3.2

Pregnancy and implantation rates were determined by demonstration of fetal heartbeat


OutcomesSecondary outcomes

  • Clinical pregnancy rate: presented as percentage, with number of participants in study group as the denominator


Additional outcomes

  • Implantation rate: presented as percentage; denominator was unclear. No raw data available


NotesAbstract of ASRM conference presentation

The primary author was contacted regarding unclear details in published abstract, but further participation was declined. So some uncertainty cannot be resolved


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation into treatment or control group by a computer-generated randomisation sheet

Allocation concealment (selection bias)Unclear riskAllocation was correctly performed, but concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding was unclear

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported. Length of follow-up per participant was unclear. No intention-to-treat analysis was reported

Selective reporting (reporting bias)Low riskClinical pregnancy and implantation rates were reported in a prespecified way

Other biasHigh riskTrial was commercially funded by Vitrolife. Same transfer media brand was used in treatment and control groups. Transfer media were comparable, with the addition of EmbryoGlue to the treatment group. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

Simon 2003

MethodsParallel randomised controlled trial

Prospective participant recruitment

Non-consecutive group sampling

Single-centre trial performed at the IVF Unit of the Department of Obstetrics and Gynecology of the Hadassah University Hospital Ein Kerem in Jerusalem, Israel

Inclusion criteria: women had to be 35 years of age or younger with at least three embryos suitable for transfer and three or fewer previous treatment failures

No power calculation was performed, information was received by contacting the study author

Participants were followed up until the pregnancy had ended

No intention-to-treat analysis was performed

Participants were enrolled in the study with only a single cycle

The trial received no commercial funding


Participants80 participants were recruited and were randomly assigned to a treatment group of 40 or a control group of 40. No loss of participants was reported, so all were analysed

A total of 200 embryos were transferred: 103 in the treatment group, 97 in the control group

Mean age (SD): treatment group 28.7 (3.3), control group 29.7 (3.8) years

Primary or secondary subfertility not reported

Cause and duration of subfertility not reported

Both IVF and ICSI cases were included. Participants could not have received more than three previous treatments

No age analysis was performed


InterventionsEmbryo transfers in culture medium were supplemented with 0.5 mg/ml HA versus transfer in culture medium

Embryos were cultured in P1 medium containing 10% synthetic serum substitute (SSS)

Embryos in treatment group were exposed to HA for five to 10 minutes before transfer

Randomisation was performed on the day of embryo transfer

Transfer was performed on day three of embryo development

Contact with the study authors indicated that a frozen-thaw protocol was followed

No donor oocytes were included in the trial

The P1 culture/transfer medium was manufactured by Irvine Scientific. The HA was manufactured by Biolon, Bio-Technology Ltd

Mean number of embryos transferred (SD): treatment group 2.6 (0.6), control group 2.4 (0.5)

Methods of pregnancy determination: hCG pregnancy test, demonstration of a gestational sac on transvaginal ultrasound scan and determination of fetal viability (fetal heartbeat) on serial ultrasounds


OutcomesPrimary outcomes

  • Live birth rate: defined as number of pregnancies resulting in a delivery divided by number of participants in the group. Unclear regarding why actual results for data stated in the Results table are not the same as those reported in the article


Secondary outcomes

  • Ongoing pregnancy rate: defined as number of pregnancies not ended by abortion at time of manuscript submission
  • Clinical pregnancy rate: defined as number of pregnant participants divided by group size
  • Multiple pregnancy rate: defined as number of twin pregnancies divided by number of pregnancies


Additional outcomes

  • Implantation rate: defined as number of gestation sacs divided by number of embryos transferred


Other outcomes

  • Deliveries
  • Ongoing pregnancy rate per embryo transfer
  • Singleton pregnancy rate
  • Clinical pregnancy rate per embryo transfer


NotesAdditional data retrieved by contacting study authors


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were allocated to treatment or control arm of the trial based on what was stated in a random sealed envelope. Actual method of randomisation was not clarified, but it appears to be correct

Allocation concealment (selection bias)Low riskA sealed envelope was drawn at the laboratory when a suitable participant arrived for transfer. According to what was stated on the envelope, the participant was allocated to either arm of the trial

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth clinician and participant were blinded to treatment received by participant

Incomplete outcome data (attrition bias)
All outcomes
Low riskLive births were reported. Length of follow-up was until pregnancy ended. No intention-to-treat analysis was performed. However, no loss of participants was reported, so there was no reason for such an analysis

Selective reporting (reporting bias)Low riskClinical pregnancy and implantation rates were reported in a prespecified way. On top of this, live birth, ongoing pregnancy and multiple pregnancy were reported

Other biasLow riskStudy received no commercial funding. Transfer media in both arms of the trial were comparable, with the exception of EmbryoGlue added to the medium in the treatment group. Multiple pregnancy rate was reported

Urman 2008

MethodsParallel randomised controlled trial

Prospective patient recruitment

Consecutive group sampling

Single-centre trial performed at the Assisted Reproduction Unit of the American Hospital of Istanbul, Turkey

Participants with treatment cycles reaching embryo transfer were included in this study. The IVF/ICSI cycles had to be fresh and had to use the participant's own oocytes

An a priori power calculation revealed that 537 participants would be necessary in each study group to detect a 15% increase in clinical pregnancy rate

The maximum length of follow-up per participant was 16 weeks, but the average length of follow-up per participant was unclear

All analyses were done according to the intention-to-treat principle

Only one treatment cycle per participant was included in the trial


ParticipantsA total of 1282 couples undergoing IVF/ICSI were recruited and randomly assigned to a treatment group of 639 and a control group of 643. 825 of the 1282 received an embryo transfer on day three of embryo development and 457 on day five. No loss of participants was reported, so the data on 1282 couples were analysed. A total of 3487 embryos were transferred: 1718 in the treatment group and 1769 in the control group

Mean age: treatment group 32.8, control group 32.9 years

Primary and/or secondary subfertility not reported

Causes of subfertility included male factor, ovarian, endometriosis, tubal factor and unexplained causes

Mean duration of subfertility: treatment group 6.9 years, control group 7.2 years

Participants underwent both IVF and ICSI

Mean number of previous treatment cycles: treatment group 2.0, control group 2.1

Age analysis: women < 35 years versus women ≥ 35 years of age


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G2 version 3 (0.125 mg/ml HA) supplemented with HSA (human serum albumin)

All embryos were cultured in G1 version three until day three and in G2 version three from day three onwards

The EmbryoGlue used for the trial was provided by the American Hospital of Istanbul

Randomisation was performed on day of embryo transfer

Embryos in treatment group were exposed to EmbryoGlue for 30 minutes before transfer

Transfer was performed on day three or day five of embryo development

All embryos were fresh, no frozen-thaw protocol was followed

No donor oocytes were included

All culture and transfer media were manufactured by Vitrolife

Mean number of embryos transferred: treatment group 2.69, control group 2.75

Method of pregnancy determination: hCG pregnancy test and demonstration of gestational sac on transvaginal ultrasound


OutcomesSecondary outcomes

  • Clinical pregnancy rate: defined as the presence of at least one gestational sac on ultrasound divided by group size of participants
  • Multiple pregnancy rate: number of multiple pregnancies divided by group size
  • Adverse event rate: number of abortions divided by group size


Additional outcomes

  • Implantation rate: number of gestational sacs divided by number of embryos transferred and multiplied by 100


Other outcomes studied

  • Implantation and clinical pregnancy rates stratified for the following groups: women < 35 years of age, women ≥ 35 years of age, women without previous implantation failure, women with previous implantation failure, good quality embryos and poor quality embryos


NotesEmbryo transfer was performed on day three or day five of embryo development. Outcomes were reported for all embryo transfers and for day three and day five transfers separately. When necessary (for instance for subgroup analyses), data were analysed separately


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskParticipants were randomly assigned to treatment or control group by a computer-generated randomisation list

Allocation concealment (selection bias)Low riskAllocation to study arm was performed after consecutively numbered, sealed opaque envelopes were opened

Blinding (performance bias and detection bias)
All outcomes
Low riskBoth clinician and participant were blinded to the group to which the participant was allocated

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live birth data were available. Length of follow-up was 16 weeks. Intention-to-treat analysis was performed

Selective reporting (reporting bias)High riskClinical pregnancy, implantation, adverse events and multiple pregnancy rates were reported in a prespecified way. However, ongoing pregnancy was also announced but was not reported on

Other biasLow riskThe EmbryoGlue was provided by the American Hospital, where the trial was performed. All media were manufactured by the same company (Vitrolife) and were therefore comparable, with the exception of EmbryoGlue added to the medium in the treatment group. Multiple pregnancy rate was reported

Walker 2005

MethodsParallel randomised controlled trial

Prospective participant recruitment

Group sampling unclear

Single-centre trial performed at the Mayo Clinic College of Medicine in Rochester, Minnesota, USA. However, one of the authors was based at the London Bridge Fertility Clinic in London, UK

Exclusion criteria: prior participation in this study, blastocyst-stage embryos, single embryo transfer for medical reasons, prior embryo transfer with a large amount of blood on the catheter, three or more consecutive failed embryo transfers. Participants appear to have a maximum age of 39 years

Unclear whether a power calculation was performed or if the number of included participants was planned prior to trial commencement

Trial received no commercial funding

Actual length of follow-up per participant was unclear

Unclear whether an intention-to-treat analysis was performed

Unclear whether participants could partake in multiple treatment cycles


ParticipantsOf a planned total of 250 participants, 98 were recruited and randomly assigned. By the time of publication of this interim analysis, only 68 of these 98 completed treatment: 34 in the treatment group and 34 in the control group. The text was not clear on whether all 98 participants were randomly assigned, or just the 68. It appears that 30 participants were lost, so data on the 68 participants were analysed. For the data analysis of the review, the group size of 34 was used as the denominator

Total number of embryos transferred was unclear

Mean age of women (SD): treatment group 31.1 (4.0), control group 30.6 (4.4) years

Not reported whether study concerned primary and/or secondary subfertility, although no difference between treatment and control groups was reported regarding previous live births

Causes and duration of subfertility were not reported

The trial appears to focus only on IVF participants, not on participants given ICSI. Participants could not have had more than two consecutive previous treatment failures, but actual data per study group were not reported

Age analysis: Participants were stratified by age (< 35 and 35 to < 39 years)


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G1 version 3 (0.125 mg/ml HA)

All embryos were cultured in G1 version three

Timing of randomisation was unclear

Timing of transfer during embryo development was unclear

Embryos in treatment group were exposed to EmbryoGlue just before transfer

All transferred embryos were frozen-thawed

Unclear whether donor oocytes were included

All transfer and culture media were manufactured by Vitrolife

Mean number of embryos transferred (SD): treatment group 2.2 (0.7), control group 2.2 (0.6)

Method of pregnancy demonstration was not reported


OutcomesSecondary outcomes

  • Clinical pregnancy rate: stated in percentage with the number of participants as the denominator
  • Multiple pregnancy rate: stated in percentage, defined as multiple gestations. Denominator was unclear


Additional outcomes

  • Implantation rate: stated as percentage, denominator unclear. (total of transferred embryos was unclear)


Other outcomes

  • Biochemical pregnancy rate: defined as positive pregnancy rate
  • Previous live birth


NotesAbstract of ASRM conference presentation of an interim analysis of a bigger study. Contact with the study authors of Morbeck 2007 revealed that the bigger study appeared to be theirs. Therefore, the data from this study of Walker et al were not analysed, although the study remains included for additional information


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly assigned to treatment or control group, but method of randomisation was not reported

Allocation concealment (selection bias)Unclear riskMethod of allocation concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding was unclear

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported. Length of follow-up was unclear. Unclear what happened to 30 of the 98 included participants; whether they were randomly assigned, and if so, whether an intention-to-treat analysis was performed

Selective reporting (reporting bias)Low riskAll outcomes were reported in a prespecified way

Other biasLow riskNo commercial funding. All media used were obtained from the same manufacturer and therefore are comparable, with the exception of EmbryoGlue added to the medium in the treatment group. Multiple pregnancy rate was reported

Yakin 2004

MethodsParallel randomised controlled trial

Prospective participant recruitment

Method of participant sampling was unclear

Single-centre trial performed at the Assisted Reproduction Unit of the VKV American Hospital in Istanbul, Turkey

Included embryos had to be frozen-thawed

Unclear whether a power calculation was performed

Length of follow-up was not reported. Not clear whether an intention-to-treat analysis was performed, nor whether any loss to follow-up occurred

Only one treatment cycle per participant was included in the trial


ParticipantsSupernumerary embryos were cryopreserved in 204 cycles; only one cycle was included per patient, so this means that 204 participants were recruited. Only 129 embryos were thawed and randomly assigned to a treatment group of 64 or a control group of 65. Some confusion exists regarding the group size (see Notes). No further loss was reported, so the data on 129 participants were analysed

Total number of embryos transferred was unclear

Mean age: treatment group 31.6, control group 32.1 years

Not reported whether study concerned primary or secondary subfertility

Cause and duration of subfertility not reported

Not reported whether study concerned IVF or ICSI participants, or both, nor whether participants had received previous subfertility treatments

No age analysis was performed


InterventionsEmbryo transfer in EmbryoGlue (0.5 mg/ml HA) versus transfer in G2 version three culture medium (0.125 mg/ml HA)

All embryos were cultured in G1 version three medium, followed by G2 version three on day three of embryo development

Randomisation was performed on day of embryo transfer

Exposure time to EmbryoGlue before transfer was not reported

All embryos were frozen on day three of development and were transferred after thawing, which means that transfer was also performed on day three of development

Unclear whether donor oocytes were included in trial

All culture and transfer media were manufactured by Vitrolife

Mean number of embryos transferred: treatment group 3.1, control group 3.2

Method of pregnancy determination was not reported


OutcomesSecondary outcomes

  • Clinical pregnancy rate: reported as a percentage, appears to be percentage of the group size. No definitions given


Additional outcomes

  • Implantation rate: reported as a percentage, but unclear of what. No definitions given


Other outcomes

  • Cryosurvival rate


NotesAbstract of ESHRE conference presentation. In the text of the abstract, it is stated that the treatment group consisted of 65 participants and the control group of 64 participants, although data are presented the other way around in the Results table


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskParticipants were randomly assigned to treatment or control group, but it is unclear in what way

Allocation concealment (selection bias)Unclear riskAllocation concealment was unclear

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding was not reported

Incomplete outcome data (attrition bias)
All outcomes
High riskNo live births were reported. 204 cycles were frozen, but only 129 were thawed. It remains unclear why. Length of follow-up was unclear. No intention-to-treat analysis was reported

Selective reporting (reporting bias)Low riskImplantation and clinical pregnancy rates were reported in a prespecified way

Other biasHigh riskUnclear whether trial received any commercial funding. All media were manufactured by Vitrolife; study groups were therefore comparable, with the exception of EmbryoGlue added to the medium in the treatment group. No multiple pregnancy rate was reported, although multiple embryos were transferred per cycle

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Balaban 2005Quasi-randomised trial. Randomisation was undertaken according to alternating weekdays

Bungum 2003Randomised controlled trial comparing implantation and pregnancy rates between two different culture media, both containing HA. Not suitable for this systematic review because this RCT did not compare a treatment group with addition of an adherence compound versus a control group devoid of, or with a lower concentration of, such a compound

Chao 2008Quasi-randomised trial. Allocation to treatment or control group was based on consecutive participant list. Every other participant was placed in the treatment group. Information was retrieved by contacting study authors

Chatziioannou 2010RCT comparing different embryo culture media. Not suitable for this systematic review because this RCT did not compare a treatment group with addition of an adherence compound versus a control group devoid of, or with a lower concentration of, such a compound

Feichtinger 1990Preliminary trial, not an RCT

Feichtinger 1992Quasi-randomised trial. Randomisation to treatment or control arm of the trial was based on the week in which embryo transfer took place

Hambiliki 2010Quasi-randomised trial. Randomisation to treatment or control arm of the trial according to alternating weeks

Karimian 2004Duplication of data from Valojerdi 2006 trial, which was quasi-randomised as well

Loutradi 2008Review on trials studying the effect of hyaluronic acid on embryo implantation rates. However, not all reviewed trials were RCTs

Nakagawa 2012Quasi-randomised trial. Allocation to different treatment groups was based on odd or even identification numbers

Nakagawa 2012-IIConference abstract of quasi-randomised trial (Nakagawa 2012)

Romano 2004Randomised controlled trial comparing implantation and pregnancy rates between three different culture media. Not suitable for this systematic review because this RCT did not compare a treatment group with addition of an adherence compound versus a control group devoid of, or with a lower concentration of, such a compound

Sallam 2010Meta-analysis of different methods of assisted reproductive technologies, including the use of EmbryoGlue. No data were reported, only lack of evidence of a beneficial treatment effect

Sieren 2006Randomised controlled trial comparing implantation and pregnancy rates between two different culture media but without studying the specific effect of the addition of HA. This RCT did not compare a treatment group with addition of an adherence compound versus a control group devoid of, or with a lower concentration of, such a compound

Sifer 2009Randomisation of oocytes instead of participants

Sun 2010Retrospective analysis

Valojerdi 2006Quasi-randomisation. Randomisation to treatment or control group was based on consecutive weekdays

Venetis 2009RCT comparing different embryo culture media, with similar levels of hyaluronic acid at time of embryo transfer

 
Comparison 1. High versus low or no hyaluronic acid

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Live birth rate6Odds Ratio (M-H, Fixed, 95% CI)Subtotals only

    1.1 High versus low or no hyaluronic acid
61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    1.2 High versus low hyaluronic acid
41626Odds Ratio (M-H, Fixed, 95% CI)1.42 [1.16, 1.73]

    1.3 High versus no hyaluronic acid
3324Odds Ratio (M-H, Fixed, 95% CI)1.35 [0.86, 2.12]

 2 Live birth rate (grouped by timing of intervention)61950Odds Ratio (M-H, Fixed, 95% CI)1.42 [1.18, 1.71]

    2.1 Early transfers
51350Odds Ratio (M-H, Fixed, 95% CI)1.37 [1.10, 1.72]

    2.2 Late transfers
3600Odds Ratio (M-H, Fixed, 95% CI)1.54 [1.11, 2.15]

 3 Live birth rate (grouped by frozen-thawed or fresh embryos)61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    3.1 Frozen-thawed embryos
2163Odds Ratio (M-H, Fixed, 95% CI)0.97 [0.52, 1.80]

    3.2 Fresh embryos
41787Odds Ratio (M-H, Fixed, 95% CI)1.46 [1.20, 1.76]

 4 Live birth rate (grouped by oocyte donation)61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    4.1 Donor oocytes
115Odds Ratio (M-H, Fixed, 95% CI)0.67 [0.08, 5.88]

    4.2 Non-donor oocytes
61935Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.18, 1.70]

 5 Live birth rate (grouped by exposure time to HA)61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    5.1 Exposure time ≤ 10 minutes
2280Odds Ratio (M-H, Fixed, 95% CI)1.38 [0.82, 2.30]

    5.2 Exposure time > 10 minutes
41670Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.16, 1.71]

 6 Live birth rate (grouped by embryo transfer policy)61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    6.1 Single embryo transfer
182Odds Ratio (M-H, Fixed, 95% CI)1.42 [0.54, 3.68]

    6.2 Multiple embryo transfer
51868Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

 7 Live birth rate (grouped by participant prognosis)61950Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.17, 1.69]

    7.1 Good prognosis
4468Odds Ratio (M-H, Fixed, 95% CI)1.17 [0.81, 1.70]

    7.2 Unselected
21482Odds Ratio (M-H, Fixed, 95% CI)1.49 [1.21, 1.84]

 8 Clinical pregnancy rate14Odds Ratio (M-H, Fixed, 95% CI)Subtotals only

    8.1 High versus low or no hyaluronic acid
143452Odds Ratio (M-H, Fixed, 95% CI)1.39 [1.21, 1.60]

    8.2 High versus low hyaluronic acid
92566Odds Ratio (M-H, Fixed, 95% CI)1.26 [1.08, 1.48]

    8.3 High versus no hyaluronic acid
6886Odds Ratio (M-H, Fixed, 95% CI)1.97 [1.46, 2.67]

 9 Clinical pregnancy rate (grouped by timing of intervention)133304Odds Ratio (M-H, Fixed, 95% CI)1.44 [1.24, 1.66]

    9.1 Early transfers
112104Odds Ratio (M-H, Fixed, 95% CI)1.51 [1.27, 1.81]

    9.2 Late transfers
41200Odds Ratio (M-H, Fixed, 95% CI)1.29 [1.01, 1.66]

 10 Clinical pregnancy rate (grouped by frozen-thawed or fresh embryos)123090Odds Ratio (M-H, Fixed, 95% CI)1.30 [1.12, 1.51]

    10.1 Frozen-thawed embryos
4506Odds Ratio (M-H, Fixed, 95% CI)1.14 [0.77, 1.69]

    10.2 Fresh embryos
92584Odds Ratio (M-H, Fixed, 95% CI)1.33 [1.13, 1.56]

 11 Clinical pregnancy rate (grouped by oocyte donation)72145Odds Ratio (M-H, Fixed, 95% CI)1.29 [1.09, 1.53]

    11.1 Donor oocytes
249Odds Ratio (M-H, Fixed, 95% CI)1.44 [0.43, 4.79]

    11.2 Non-donor oocytes
72096Odds Ratio (M-H, Fixed, 95% CI)1.29 [1.09, 1.53]

 12 Clinical pregnancy rate (grouped by exposure time to HA before transfer)112988Odds Ratio (M-H, Fixed, 95% CI)1.34 [1.16, 1.56]

    12.1 Exposure time ≤ 10 minutes
5616Odds Ratio (M-H, Fixed, 95% CI)1.65 [1.18, 2.31]

    12.2 Exposure time > 10 minutes
62372Odds Ratio (M-H, Fixed, 95% CI)1.28 [1.08, 1.51]

 13 Clinical pregnancy rate (grouped by participant prognosis)143452Odds Ratio (M-H, Fixed, 95% CI)1.39 [1.21, 1.60]

    13.1 Poor prognosis
2288Odds Ratio (M-H, Fixed, 95% CI)4.53 [2.54, 8.10]

    13.2 Good prognosis
5742Odds Ratio (M-H, Fixed, 95% CI)1.21 [0.88, 1.66]

    13.3 Unselected participants
72422Odds Ratio (M-H, Fixed, 95% CI)1.30 [1.10, 1.53]

 14 Clinical pregnancy rate (grouped by embryo transfer policy)143452Odds Ratio (M-H, Fixed, 95% CI)1.39 [1.21, 1.60]

    14.1 Single embryo transfer
1296Odds Ratio (M-H, Fixed, 95% CI)1.19 [0.67, 2.09]

    14.2 Multiple embryo transfer
133156Odds Ratio (M-H, Fixed, 95% CI)1.41 [1.22, 1.63]

 15 Multiple pregnancy rate51951Odds Ratio (M-H, Fixed, 95% CI)1.86 [1.49, 2.31]

 16 Adverse event rate41525Odds Ratio (M-H, Fixed, 95% CI)0.74 [0.49, 1.12]

 17 Implantation rate8Odds Ratio (M-H, Fixed, 95% CI)Totals not selected

 
Comparison 2. Fibrin sealant versus no fibrin sealant

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Clinical pregnancy rate (per randomly assigned couple)1211Odds Ratio (M-H, Fixed, 95% CI)0.98 [0.54, 1.78]

 2 Adverse event rate (per randomly assigned couple)1211Odds Ratio (M-H, Fixed, 95% CI)5.55 [0.26, 117.06]

 3 Implantation rate (per embryos transferred)1Odds Ratio (M-H, Fixed, 95% CI)Totals not selected

 
Summary of findings for the main comparison. High versus low or no hyaluronic acid for assisted reproductive technologies

High versus low or no hyaluronic acid for assisted reproductive technologies

Population: couples undergoing embryo transfer
Settings: assisted reproduction
Intervention: high hyaluronic acid
Comparison: low or no hyaluronic acid

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

Low or no hyaluronic acidHigh hyaluronic acid

Live birth ratehigh versus low or no hyaluronic acid374 per 1000458 per 1000

(412 to 503)
OR 1.41
(1.17 to 1.69)
1950
(six studies)
⊕⊕⊕⊝
moderate1

Live birth ratehigh versus low hyaluronic acid347 per 1000430 per 1000

(382 to 479)
OR 1.42
(1.16 to 1.73)
1626
(four studies)
⊕⊕⊕⊝
moderate2

Live birth ratehigh versus no hyaluronic acid385 per 1000458 per 1000

(350 to 570)
OR 1.35
(0.86 to 2.12)
324
(three studies)
⊕⊕⊕⊝
moderate1

Clinical pregnancy ratehigh versus low or no hyaluronic acid350 per 1000428 per 1000

(394 to 462)
OR 1.39
(1.21 to 1.6)
3452
(14 studies)
⊕⊕⊕⊝
moderate1,3

Clinical pregnancy ratehigh versus low hyaluronic acid448 per 1000506 per 1000

(467 to 546)
OR 1.26
(1.08 to 1.48)
2566
(nine studies)
⊕⊕⊕⊝
moderate2

Clinical pregnancy ratehigh versus no hyaluronic acid178 per 1000299 per 1000

(241 to 367)
OR 1.97
(1.46 to 2.67)
886
(six studies)
⊕⊕⊕⊝
moderate1,4

Multiple pregnancy rate20 per 100037 per 1000

(30 to 45)
OR 1.86
(1.49 to 2.31)
1951
(five studies)
⊕⊕⊕⊝
moderate1

Adverse event rate63 per 100048 per 1000

(32 to 70)
OR 0.74
(0.49 to 1.12)
1525
(four studies)
⊕⊕⊕⊝
moderate2

*The basis for the assumed risk is the median control group risk across studies. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; OR: Odds ratio.

GRADE Working Group grades of evidence.
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 1All studies except one at high risk of bias in one or more domains.
2All studies at high risk of bias in one or more domains.
3Moderate heterogeneity: I2 = 46%.
4Moderate heterogeneity: I2 = 60%.
 
Summary of findings 2. Fibrin sealant versus no fibrin sealant for assisted reproductive technologies

Fibrin sealant versus no fibrin sealant for assisted reproductive technologies

Population: couples undergoing embryo transfer
Settings: assisted reproduction
Intervention: fibrin sealant versus no fibrin sealant

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

No fibrin sealantFibrin sealant

Clinical pregnancy rate (per randomly assigned couple)291 per 1000287 per 1000
(181 to 422)
OR 0.98
(0.54 to 1.78)
211
(one study)
⊕⊝⊝⊝
very low1,2

Adverse event rate (per randomly assigned couple)Zero per 1000Zero per 1000
(zero to zero)
OR 5.55
(0.26 to 117.06)
211
(one study)
⊕⊝⊝⊝
very low1,2

*The basis for the assumed risk is the control group risk. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; OR: Odds ratio.

GRADE Working Group grades of evidence.
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 1High risk of attrition bias.
2Single study, wide confidence intervals compatible with appreciable benefit or harm, or no effect.