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Amniotomy for shortening spontaneous labour

  1. Rebecca MD Smyth1,*,
  2. Carolyn Markham2,
  3. Therese Dowswell3

Editorial Group: Cochrane Pregnancy and Childbirth Group

Published Online: 18 JUN 2013

Assessed as up-to-date: 10 JUN 2013

DOI: 10.1002/14651858.CD006167.pub4


How to Cite

Smyth RMD, Markham C, Dowswell T. Amniotomy for shortening spontaneous labour. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD006167. DOI: 10.1002/14651858.CD006167.pub4.

Author Information

  1. 1

    The University of Manchester, School of Nursing, Midwifery and Social Work, Manchester, UK

  2. 2

    Northampton, UK

  3. 3

    The University of Liverpool, Cochrane Pregnancy and Childbirth Group, Department of Women's and Children's Health, Liverpool, UK

*Rebecca MD Smyth, School of Nursing, Midwifery and Social Work, The University of Manchester, Jean McFarlane Building, Oxford Road, Manchester, M13 9PL, UK. rebecca.smyth@manchester.ac.uk.

Publication History

  1. Publication Status: New search for studies and content updated (no change to conclusions)
  2. Published Online: 18 JUN 2013

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Characteristics of included studies [ordered by study ID]
Ajadi 2006

MethodsRandomisation: blocked randomisation technique using table of random numbers.
Allocation concealment: sequentially-numbered, sealed opaque envelopes, eligible women.
Blinding: woman and caregiver not blinded.
Follow-up: 100%.


Participants128 women were enrolled, 64 in experimental group and 64 in control group.
Eligibility: spontaneous labour, 37-42 weeks' gestation, singleton pregnancies, cephalic presentation, cervical dilatation of at least 4 cm but less than 6 cm, multiparous and primiparous women.
Exclusion: previous caesarean section, haemoglobinopathies, hypertension, malpresentation, multiple pregnancies APH, suspected IUGR, fetal distress.
Mean cervical dilatation at entry to study: 4.6 ± 0.32 in the amniotomy group and 4.7 ± 0.30.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: mode of delivery, oxytocin, length of second stage of labour.
Fetal/infant: Apgar score (no data given).


NotesMulticentre/single centre: multicentre (2 sites).
Setting: Nigeria.
Additional outcomes: randomisation to delivery, randomisation to full cervical dilatation, Apgar score of less than 7 at 1 minute.
In the amniotomy group 5 women had SROM after randomisation and in the intact group, 83 had amniotomy.
Author contacted March 2007 for additional data, still awaiting response (30/03/07).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskBlocked randomisation technique using table of random numbers.

Allocation concealment (selection bias)Low riskAllocation concealment: sequentially-numbered, sealed opaque envelopes, eligible women.

Blinding (performance bias and detection bias)
All outcomes
High riskWoman and caregiver not blinded. Outcome assessor - information not given about blinding.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up 100%.

Selective reporting (reporting bias)Low riskAll outcomes in the methods section have been reported on in the results section.

Other biasLow riskNo evidence of any other form of bias.

Barrett 1992

MethodsRandomisation: randomised controlled trial stratified by parity.
Allocation concealment: numbered sealed opaque envelopes.
Blinding: woman and caregiver not blinded.
Follow-up: 90%.


Participants362 women (does not include 36 women lost to follow-up), 183 in experimental group and 179 in control group.
Eligibility: spontaneous labour, 37-42 weeks' gestation, singleton pregnancies, multiparous and primiparous women.
Exclusion: none given in paper.
Mean cervical dilatation at entry to study: 4 cm in ARM group and 4.1 in the control group.


InterventionsExperimental: amniotomy.
Control: no amniotomy, once full dilatation reached any membranes that had remained intact were ruptured.


OutcomesWomen: length of first and second stage of labour, mode of delivery, pain relief - epidural, use of oxytocin.
Fetal/infant: CTG abnormality.


NotesMulticentre/single centre: single.
Setting: Leeds UK.
Additional outcomes: meconium-stained amniotic fluid, postpartum pyrexia > 38°C, umbilical vein lactate levels.
In the amniotomy group 5 women had SROM after randomisation and in the control group, 83 women (46%) had amniotomy.
Discrepancies in the number of cards drawn and the number of women entered into trial log. See text of review for further information.
Author contacted, able to confirm singletons only, but does not hold data on other outcomes (Nov 2006).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: randomised controlled trial stratified by parity.

Allocation concealment (selection bias)Low riskAllocation concealment: numbered sealed opaque envelopes.

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: woman and caregiver not blinded. Outcome assessor - information not given about blinding.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskFollow-up: 90%.

Selective reporting (reporting bias)Unclear riskAuthors stated that they were unable to report on several pre-specified outcomes (pain scores in women without epidural) due to infrequency of measurement and problems with blinding. It is not clear what pain scoring system was in use, and whether blinding of the woman or the assessor was the issue.

Apparently free from other selective reporting bias.

Other biasHigh riskDiscrepancies in the number of cards drawn and the number of women entered into trial log. Authors state in the text of the paper that they were unable to rule out the possibility of cheating. See text of review for further information.

Blanch 1998

MethodsRandomisation: to 1 of 3 different interventions using a table of random numbers.
Allocation concealment: consecutively-numbered, sealed opaque envelopes.
Blinding: participant and caregiver not blinded. Paper does not state blinding of outcome assessor.
Follow-up: 1 woman with a breech presentation was randomised in error and therefore excluded from analysis.


Participants61 women recruited, data available for 60.
Eligibility: dysfunctional labour (spontaneous) where women have not progressed satisfactorily (diagnosed using a partogram), intact membranes, singleton fetus, cephalic presentation, gestation of at least 37 weeks, cervical dilatation of at least 3 cm, full cervical effacement, contractions at least every 5 minutes lasting 20 seconds, no evidence of fetal distress, primiparous and multiparous women.
Exclusion: contraindications to oxytocin.


InterventionsExperimental: group 1 - oxytocin with amniotomy (not analysed in review), group 2 - amniotomy alone.
Control: expectant management (no amniotomy).


OutcomesWomen: caesarean section, maternal satisfaction, Apgar score, epidural, oxytocin use, instrumental vaginal delivery.
Fetal/infant: SCBU admission, cord pH.


NotesMulticentre/single centre: single centre.
Setting: Liverpool, UK.
Due to slow rate of recruitment, a decision was made to stop the trial with only half the women recruited.
Additional outcomes collected: dilatation rates, cord base excess, randomisation to delivery interval.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: to 1 of 3 different interventions using a table of random numbers.

Allocation concealment (selection bias)Low riskAllocation concealment: consecutively-numbered, sealed opaque envelopes.

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: participant and caregiver not blinded. Paper does not state blinding of outcome assessor.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 1 woman with a breech presentation was randomised in error and therefore excluded from analysis.

Selective reporting (reporting bias)High riskAdditional outcomes reported in tables (oxytocin and epidural use) not specified in the methods section.

Other biasHigh riskDue to slow rate of recruitment, a decision was made to stop the trial with only half the women recruited.

Franks 1990

MethodsRandomisation: allocated randomly using a random-number generator.
Allocation concealment: sealed envelopes.
Blinding: paper does not state.
Follow-up: 100%.


Participants53 women, 26 in experimental group and 27 in control group.
Eligibility: spontaneous labour, intact membranes, at least 36 weeks' gestation, nulliparous and multiparous women.
Exclusion: multiple pregnancy, bleeding, conductive anaesthesia, premature labour, more than 6 cm dilated, contraindication to amniotomy, breech presentation.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: caesarean section, analgesia use, length of first stage, length of second stage.
Fetal/infant: Apgar score.


NotesMulticentre/single centre: single centre.
Setting: New York, USA.
In the control group, 16 (59%) women received an amniotomy before full dilatation, at clinician's discretion.
Additional outcomes: weight of baby, time from randomisation to delivery.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: allocated randomly using a random-number generator.

Allocation concealment (selection bias)Unclear riskAllocation concealment: sealed envelopes.

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: paper does not state.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)High riskAll pre-specified outcomes reported

Other biasUnclear riskPapare suggests additional unspecified analyses performed (outliers excluded).

Fraser 1991

MethodsRandomisation: non-stratified block randomisation (Zelen randomisation).
Allocation concealment: numbered sealed opaque envelopes.
Blinding: woman and caregiver not blinded, outcome assessor blinded regarding fetal heart tracing assessment.
Follow-up: 100%.


Participants97 women recruited, 50 in control group, 47 in experimental group.
Eligibility: nulliparous, spontaneous labour, single fetus, cephalic presentation, at least 38 weeks' pregnant, normal FHR tracing on admission, cervical dilatation of at least 5 cm.
Exclusion: history of genital herpes, proteinuria or hypertension.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: oxytocin use, caesarean section, instrumental vaginal delivery, length of second stage of labour.
Fetal/infant: suboptimal FHR tracing, Apgar score, cord pH, cephalhaematoma.


NotesMulticentre/single centre: single centre.
Setting: Quebec, Canada.
19 out of 50 (38%) women in the control group had an amniotomy - 11 for augmentation and 8 for fetal distress.
Additional outcomes: interval from randomisation to delivery, birthweight, blood transfusion, labour onset to rupture of membranes, ventilation of infant
Women with cervical dilatation of less than 3 cm were randomised when the head was fixed in the pelvis and the cervix had undergone a change in dilatation after admission. Women with cervical dilatation of at least 3 cm were randomised when the fetal head was fixed in the pelvis.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: non-stratified block randomisation (Zelen randomisation).

Allocation concealment (selection bias)Low riskAllocation concealment: numbered sealed opaque envelopes.

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: woman and caregiver not blinded, outcome assessor blinded regarding fetal heart tracing assessment.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Unclear riskDifficult to extract planned outcomes from text.

Other biasHigh riskAdditional subgroup analysis performed, not pre-specified in methodology regarding women who achieved vaginal delivery only.

Fraser 1993

MethodsRandomisation: centralised and group assignment stratified according to medical centre and degree of cervical dilatation less than 3 cm vs at least 3 cm.
Allocation concealment: telephone answering service.
Blinding: woman and caregiver not blinded, outcome assessor blinded regarding fetal heart tracing assessment.
Follow-up: 100%.


Participants925 women, 462 in experimental group and 463 in control group.
Eligibility: spontaneous labour, nulliparous, at least 38 weeks' gestation, single fetus, cephalic presentation, normal FHR.
Exclusion: IUGR, severe pre-eclampsia, IDDM, cervical dilatation of more than 6 cm.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: analgesia, oxytocin use, caesarean section, instrumental vaginal delivery, death, length of second stage of labour, dysfunctional labour, cord prolapse.
Fetal/infant: Apgar score, suboptimal FHR trace, cephalhaematoma, convulsions, fracture, meconium aspiration, perinatal death, SCBU.


NotesMulticentre/single centre: multicentre.
Setting: 10 in Canada, 1 in USA.
Additional outcome: birthweight, oxygen therapy and ventilation of neonate, antibiotic therapy of neonate, need for resuscitation, maternal intrapartum/postpartum fever, maternal antibiotic therapy, endometritis, wound infection, time of admission to randomisation, time of randomisation to rupture of membranes.
96% in the amniotomy group had an amniotomy in the first stage of labour compared with 51% in the control group (77% for failure to progress and 17% for fetal distress).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: centralised and group assignment stratified according to medical centre and degree of cervical dilatation less than 3 cm vs at least 3 cm.

Allocation concealment (selection bias)Low riskAllocation concealment: telephone answering service.

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: woman and caregiver not blinded, outcome assessor blinded regarding fetal heart tracing assessment.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)High riskAdditional information on epidural use and narcotic analgesia not pre-specified in methods. There was no difference, however between the intervention and control groups for these outcomes

Other biasHigh riskAdditional analysis of dystocia according to definition which had not been pre-specified (post-hoc analysis).

Garite 1993

MethodsRandomisation: randomisation by random-number computer program.
Allocation concealment: consecutively-numbered, sealed envelopes.
Blinding: no information provided.
Follow-up: 100%.


Participants459 women, 235 in amniotomy group, 224 in control group.
Eligibility: singleton pregnancy, nulliparous and multiparous women, spontaneous labour, at least 36 weeks' pregnant, intact membranes, cervical dilatation of between 4 and 6 cm, vertex presentation at or below -2 station.
Exclusion: fetal distress, chorioamnionitis on admission, previous caesarean section, pre-eclampsia, conditions making caesarean section likely, oligohydramnios, polyhydramnios.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: length of first and second stages of labour, instrumental vaginal delivery, caesarean section, oxytocin.
Fetal/infant: suboptimal FHR, Apgar score, hyperbilirubinaemia, sepsis, intracranial haemorrhage, seizures, RDS.


NotesMulticentre/single centre: single centre.
Setting: California, USA.
Additional outcomes: presence of meconium.
In the amniotomy group 12 women had SROM after randomisation and in the intact group, 55 had amniotomy had full dilatation or at delivery, 20 had amniotomy for internal fetal heart monitoring and 36 for dysfunctional labour and 13 for indeterminate reasons (31% of control group).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: randomisation by random-number computer program.

Allocation concealment (selection bias)Unclear riskAllocation concealment: consecutively-numbered, sealed envelopes.

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: no information provided.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Unclear riskPre-specified outcomes not documented in methods section.

Other biasLow riskNone evident.

Guerresi 1981

MethodsRandomisation: multiparous and primiparous women separated into 2 groups, each was then randomly divided into 2 equal subgroups.
Allocation concealment: not stated.
Blinding: no information provided.
Follow -up: 100%.


Participants100 women, 50 experimental and 50 control.
Eligibility: multiparous and primiparous women, 'term' gestation.
Exclusion: women with anatomical or functional abnormalities likely to affect the course of delivery.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: length of first and second stage of labour.
Fetal/infant: Apgar score.


NotesMulticentre/single centre: single centre.
Setting: Bologna, Italy.

Study overall recruited 300 women, 200 of which received rociverone of butylscopolamine bromide and were therefore not analysed.
Author (Prof Gori) contacted November 2007 for additional data, still awaiting response (30/03/07).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: multiparous and primiparous women separated into 2 groups, each was then randomly divided into 2 equal subgroups.

Allocation concealment (selection bias)High riskAllocation concealment: "each of the groups was randomly divided".

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: no information provided.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Low riskNo evidence.

Other biasLow riskNo evidence.

Johnson 1997

MethodsRandomisation: computer randomisation.
Allocation concealment: unclear.
Blinding: outcome assessor (statistician) unaware of allocation.
Follow-up: 100%.


Participants940 multiparous women (1550 overall, 600 nulliparous), 529 in experimental group, 411 in control group.
Eligibility: intact membranes, uncomplicated spontaneous labour, at least 36 weeks, painful uterine contractions enough to cause descent of the presenting part and cervical dilatation.
Exclusion: multiple pregnancy, non-vertex presentation, IUGR, pre-eclampsia.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: caesarean section, instrumental vaginal delivery, oxytocin.
Fetal/infant: unable to extract without further info - Apgar score, morbidity.


NotesMulticentre/single centre: single centre.
Setting: Leeds UK.

Additional outcomes: third degree tear.
Nulliparous women analysed in this trial were recruited as part of the UK amniotomy trial therefore only data from the multiparous women have been extracted from this paper for the review.
Ratio of randomisation is 4:3 amniotomy:no amniotomy due to computer programming error.
54% of women in the control group received an amniotomy.

Unable to locate and contact author (29/11/06) therefore unable to extract data for most outcomes, as no distinction between multiparous and primiparous women made. Primiparous women included in UK amniotomy study.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: computer randomisation.

Allocation concealment (selection bias)Unclear riskAllocation concealment: unclear.

Blinding (performance bias and detection bias)
All outcomes
Low riskBlinding: outcome assessor (statistician) unaware of allocation.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Unclear riskUnclear as to pre-specification of outcomes from text of review.

Other biasHigh riskComputer programming error with randomisation - see paper.

Laros 1972

MethodsRandomisation: table of random numbers.
Allocation concealment: sealed envelopes.
Blinding: no information given.
Follow-up: 100%.


Participants125 women were enrolled, 70 in experimental group and 55 in control group.
Eligibility: spontaneous labour, intact membranes, vertex presentation, gestation 36-44 weeks, cervical dilatation of between 5 and 8 cm, multiparous and primiparous women.
Exclusion: abnormal labours requiring oxytocin, caesarean section or operative vaginal delivery (possibly post-randomisation exclusions).


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: length of first stage of labour, length of second stage of labour , serious maternal morbidity and mortality.
Fetal/infant: Apgar score, perinatal morbidity and mortality.


NotesMulticentre/single centre: single centre, air force hospital.
Setting: USA.
Additional outcomes: none reported.

Additional information (unpublished) provided by the author suggests that there was post randomisation exclusion of women who did not achieve a normal delivery (see Participants).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: table of random numbers.

Allocation concealment (selection bias)Unclear riskAllocation concealment: "randomly assigned".

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: no information given.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)High riskReported outcomes that were not pre-specified - analysed with Chi² showing no difference between the 2 groups.

Other biasLow riskNo evidence.

Mikki 2007

MethodsRandomisation: randomised controlled trial stratified by parity.
Allocation concealment: sealed envelopes.
Blinding: woman and caregiver not blinded, no information given regarding blinding of the outcome assessor
Follow-up: 100%.


Participants690 women were enrolled, 340 (74 nulliparous women, 266 multiparous women) in experimental group and 350 (83 nulliparous women, 267 multiparous women) in control group.
Eligibility: low risk full-term pregnancy, singleton pregnancy, cephalic presentation, active labour, intact membranes , normal fetal heart rate.
Exclusion: IUGR, induction of labour, suspected large for dates baby ( >4.5 kg), pre-eclampsia, insulin dependent diabetes mellitus, more than 1 previous caesarean section, antepartum haemorrhage, advanced labour.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: caesarean section, length of second stage of labour (minutes), dysfunctional labour (no progress in cervical dilatation in 2 hours or ineffective uterine contractions (as defined by trial authors)), use of pain relief, oxytocin augmentation and dosage used; instrumental vaginal birth, postpartum haemorrhage (as defined by trial authors), perineal trauma irrespective of suturing.

Fetal/infant: low Apgar score less than seven at five minutes, admission to neonatal intensive care or special care nursery.


NotesMulticentre/single centre: single centre.
Setting: West Bank, Occupied Palestinian Territory.
Additional outcomes: 60.2% (n = 50) of nulliparous women and 33.8% (n = 90) of multiparous women in the control group received an amniotomy.

It was calculated that the sample size required to detect a difference of 45 minutes in the duration of labour between the 2 arms required 533 women to be enrolled to both the intervention and control groups. This was not achieved as the trial was ended prematurely (after 1 year) due to budget constraints.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: randomised controlled trial stratified by parity.

Allocation concealment (selection bias)Unclear riskAllocation concealment: "simple randomisation with sealed envelopes".

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: woman and caregiver not blinded, no information given regarding blinding of the outcome assessor.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)High riskData on perinatal death not reported in the paper, however, data provided by the author through correspondence.

Outcomes not pre-specified in the methodology.

Other biasHigh riskTrial ended due to budget constraints.

Shobeiri 2007

MethodsRandomisation: randomised.
Allocation concealment: no information given.
Blinding: no information given.
Follow-up: 100%.


Participants80 women were enrolled, 40 in experimental group and 40 in control group.
Eligibility: nulliparous, at least 38 weeks' gestation, singleton pregnancies, cephalic presentation, normal FHR, intact membranes, cervical dilatation of 3 cm or greater, painful uterine contractions every 5 minutes for at least an hour.
Exclusion: none specified.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: duration of first stage of labour, duration of second stage of labour, caesarean section, dystocia.
Fetal/infant: FHR, Apgar scores at 1 min and 5 minutes.


NotesMulticentre/single centre: single centre.
Setting: Iran.
Additional outcomes: duration of third stage of labour, interval between randomisation and membrane rupture, and randomisation and full dilatation.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: randomised.

Allocation concealment (selection bias)Unclear riskAllocation concealment: no information given.

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: no information given.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)High riskNot all outcomes pre-specified in methodology.

Other biasUnclear riskBrief report.

Stewart 1982

MethodsRandomisation: randomly allocated.
Allocation concealment: no information provided.
Blinding: not stated.
Follow-up: 100% (4 primiparous women of 68 women recruited, excluded on basis of delivery by caesarean section for cephalopelvic disproportion).


Participants68 women recruited, 64 analysed. 34 women in intervention group and 30 women in control group.
Eligibility: nulliparous (32) and multiparous women (32), 38 to 42 weeks' gestation, spontaneous labour, singleton fetus, intact membranes, cervical dilatation of no more than 4 cm and a cervical score of more than 6.
Exclusion: caesarean section post randomisation.


InterventionsExperimental: amniotomy.
Control: no amniotomy until full dilatation.


OutcomesWomen: oxytocin use, instrumental vaginal delivery, analgesia, amniotomy to delivery interval.
Fetal/infant: Apgar score, meconium-stained liquor, perinatal death, suboptimal FHR, jaundice.


NotesMulticentre/single centre: single centre.
Setting: UK - Glasgow, Scotland.
Additional outcomes: umbilical artery pH of less than 7.15, SCBU admission for > 12 hours, mean birthweight.

CTG tracing - 33 women in amniotomy group had continuous monitoring, of which 30 traces were suitable for analysis. In the control group 26 women had continuous monitoring of which 21 traces were suitable for analysis.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: randomly allocated.

Allocation concealment (selection bias)Unclear riskAllocation concealment: no information provided.

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: not stated.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100% (4 primiparous women of 68 women recruited, excluded on basis of delivery by caesarean section for cephalopelvic disproportion).

Selective reporting (reporting bias)High riskOutcomes not all pre-specified in methodology.

Other biasHigh riskWomen who were delivered by caesarean section were excluded from analysis.

UK Amniotomy 1994

MethodsRandomisation: random-number tables at 5 centres, computer randomisation (random-number generation) at 1 centre.
Allocation concealment: numbered sealed opaque envelopes.
Blinding: not stated.
Follow-up: 100%.


Participants1463 women entered 782 in experimental group and 681 in control group.
Eligibility: women in first pregnancy (defined as no previous pregnancy of greater than 28 weeks' gestation), 37 to 42 weeks' gestation, spontaneous labour, singleton fetus, cephalic presentation, intact membranes.
Exclusion: multiparous.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: maternal satisfaction (unable to extract data), caesarean section, instrumental vaginal delivery, analgesia, infection requiring antibiotics.
Fetal/infant: Apgar score, SCBU admission, jaundice, perinatal death, convulsions.


NotesMulticentre/single centre: multicentre.
Setting: UK - Leeds, Shotley Bridge, Stoke-on-Trent, Tameside, Staffs, Glasgow.
Additional outcomes: time from randomisation to delivery, intubation and ventilation of neonate, maternal blood transfusion.
At St James, Leeds, ratio of randomisation is 4:3 amniotomy:no amniotomy due to computer programming error.
Author contacted November 2006 and March 2007 for additional data, still awaiting response (30/03/07).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandomisation: random-number tables at 5 centres, computer randomisation (random-number generation) at 1 centre.

Allocation concealment (selection bias)Low riskAllocation concealment: numbered sealed opaque envelopes.

Blinding (performance bias and detection bias)
All outcomes
Unclear riskBlinding: not stated.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Low riskNo evidence.

Other biasHigh riskComputer programming error leading to imbalanced randomisation.

Wetrich 1970

MethodsRandomisation: controlled randomised study.
Allocation concealment: blind draw to randomly assign women.
Blinding: woman and caregiver not blinded.
Follow-up: 100%.


Participants32 women, 16 in experimental group and 16 in control group.
Eligibility: normally progressive spontaneous labour prior to 6 cm dilatation, intact membranes at 6 cm dilatation, vertex fixed in pelvis and applied to cervix, singleton fetus, vertex presentation, EFW 2500-4000 g, cervical dilatation at time of ARM no greater and no less than 6 cm, participant followed personally throughout duration of labour.
Exclusion: multiparous women, dysfunctional labour, severe pre-eclampsia, diabetes, placental abruption, rhesus isoimmunisation.


InterventionsExperimental: amniotomy.
Control: no amniotomy.


OutcomesWomen: length of second stage of labour, mode of delivery, pain relief.
Fetal/infant: perinatal death.


NotesMulticentre/single centre: single centre.
Setting: Iowa, USA.
Additional outcomes: infant weight, time from 6 cm to full dilatation.

In control group, 5 women had amniotomy at full dilatation.
It was noted approximately 2/3 of the way through the study that more women in the spontaneous rupture group had received caudal anaesthesia than the amniotomy group. In the terminal parts of the study the difference was evened up by arbitrary assignment of anaesthesia.

Unable to locate author through extensive Internet search.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskRandomisation: controlled randomised study.

Allocation concealment (selection bias)High riskAllocation concealment: blind draw to randomly assign women.

Blinding (performance bias and detection bias)
All outcomes
High riskBlinding: woman and caregiver not blinded.
No information reported for outcome assessor.

Incomplete outcome data (attrition bias)
All outcomes
Low riskFollow-up: 100%.

Selective reporting (reporting bias)Low riskNo evidence, but see below.

Other biasHigh riskArbitrary assignment of anaesthesia used due to an observation 2/3 of the way through the study that more women in the control group required epidural anaesthesia, despite anaesthesia being specified as an outcome.

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Abdullah 2010Quasi-randomised.

Garmi 2008Study looking at effect of amniotomy for abnormally progressing labour.

Levy 2002IOL with Foley catheter prior to amniotomy. Women not in spontaneous labour.

Li 2006This is a review article (meta-analysis).

Martell 1976Quasi-randomised.

Nachum 2010Comparison groups included augmentation with oxytocin, amniotomy or a combination of both.

Schwarcz 1975Quasi-randomised.

Schwarcz 1973Women in control group excluded if SROM before full dilatation. Paper looks at effect of amniotomy or no amniotomy on FHR only, and not on spontaneous labour outcomes. Author contacted for information about other outcomes not included.

Surichamorn 1998Unable to contact authors and unable to ascertain whether a randomised or quasi-randomised trial.

 
Comparison 1. Amniotomy versus no amniotomy

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

 1 Length of first stage of labour51127Mean Difference (IV, Random, 95% CI)-20.43 [-95.93, 55.06]

    1.1 Primiparous women
4379Mean Difference (IV, Random, 95% CI)-57.93 [-152.66, 36.80]

    1.2 Multiparous women
3386Mean Difference (IV, Random, 95% CI)23.10 [-50.89, 97.09]

    1.3 Primiparous and multiparous women
1362Mean Difference (IV, Random, 95% CI)-18.0 [-67.54, 31.54]

 2 Caesarean section95021Risk Ratio (M-H, Fixed, 95% CI)1.27 [0.99, 1.63]

    2.1 Primiparous women
62674Risk Ratio (M-H, Fixed, 95% CI)1.15 [0.88, 1.51]

    2.2 Multiparous women
21473Risk Ratio (M-H, Fixed, 95% CI)1.76 [0.65, 4.76]

    2.3 Primiparous and multiparous women
3874Risk Ratio (M-H, Fixed, 95% CI)2.36 [0.99, 5.63]

 3 Maternal satisfaction with childbirth experience184Mean Difference (IV, Fixed, 95% CI)-1.10 [-7.15, 4.95]

 4 Apgar score less than 7 at 5 minutes63598Risk Ratio (M-H, Fixed, 95% CI)0.53 [0.28, 1.00]

    4.1 Primiparous women
42542Risk Ratio (M-H, Fixed, 95% CI)0.42 [0.20, 0.88]

    4.2 Primiparous and multiparous women
2523Risk Ratio (M-H, Fixed, 95% CI)1.30 [0.26, 6.43]

    4.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.06, 15.96]

 5 Length of second stage81927Mean Difference (IV, Random, 95% CI)-1.33 [-2.92, 0.26]

    5.1 Primiparous women
7653Mean Difference (IV, Random, 95% CI)-5.43 [-9.98, -0.89]

    5.2 Multiparous women
4919Mean Difference (IV, Random, 95% CI)-1.19 [-2.92, 0.53]

    5.3 Primiparous and multiparous women
1355Mean Difference (IV, Random, 95% CI)0.60 [-2.46, 3.66]

 6 Dysfunctional labour31695Risk Ratio (M-H, Random, 95% CI)0.60 [0.44, 0.82]

    6.1 Primiparous women
1157Risk Ratio (M-H, Random, 95% CI)0.49 [0.33, 0.73]

    6.2 Multiparous women
1533Risk Ratio (M-H, Random, 95% CI)0.44 [0.31, 0.62]

    6.3 Primiparous and multiparous women
21005Risk Ratio (M-H, Random, 95% CI)0.75 [0.64, 0.88]

 7 Use of pain relief - epidural/narcotic83475Risk Ratio (M-H, Random, 95% CI)1.05 [0.96, 1.14]

    7.1 Primiparous women
52463Risk Ratio (M-H, Random, 95% CI)0.99 [0.94, 1.04]

    7.2 Multiparous women
1533Risk Ratio (M-H, Random, 95% CI)1.45 [1.16, 1.80]

    7.3 Primiparous and multiparous women
3479Risk Ratio (M-H, Random, 95% CI)1.15 [0.78, 1.68]

 8 Oxytocin augmentation84264Risk Ratio (M-H, Random, 95% CI)0.72 [0.54, 0.96]

    8.1 Primiparous women
31179Risk Ratio (M-H, Random, 95% CI)0.79 [0.56, 1.11]

    8.2 Multiparous women
1533Risk Ratio (M-H, Random, 95% CI)0.43 [0.30, 0.60]

    8.3 Primiparous and multiparous women
52552Risk Ratio (M-H, Random, 95% CI)0.77 [0.46, 1.28]

 9 Instrumental vaginal birth105121Risk Ratio (M-H, Fixed, 95% CI)0.99 [0.87, 1.13]

    9.1 Primiparous women
62664Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.87, 1.15]

    9.2 Multiparous women
21444Risk Ratio (M-H, Fixed, 95% CI)1.12 [0.65, 1.95]

    9.3 Primiparous and multiparous women
41013Risk Ratio (M-H, Fixed, 95% CI)0.84 [0.55, 1.29]

 10 Caesarean section for fetal distress1690Risk Ratio (M-H, Fixed, 95% CI)3.21 [0.66, 15.60]

    10.1 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)4.49 [0.51, 39.25]

    10.2 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)2.01 [0.18, 22.01]

 11 Caesarean section for prolonged labour1690Risk Ratio (M-H, Fixed, 95% CI)0.45 [0.07, 3.03]

    11.1 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.37 [0.02, 9.03]

    11.2 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)0.50 [0.05, 5.50]

 12 Antepartum haemorrhage1690Risk Ratio (M-H, Fixed, 95% CI)0.63 [0.08, 4.84]

    12.1 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.37 [0.02, 9.03]

    12.2 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.06, 15.96]

 13 Postpartum haemorrhage21822Risk Ratio (M-H, Fixed, 95% CI)0.46 [0.14, 1.50]

    13.1 Primiparous and multiparous women
11132Risk Ratio (M-H, Fixed, 95% CI)0.19 [0.02, 1.68]

    13.2 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.56 [0.05, 6.06]

    13.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.14, 7.07]

 14 Cord prolapse21615Risk Ratio (M-H, Fixed, 95% CI)1.00 [0.14, 7.10]

    14.1 Primiparous and multiparous women
1925Risk Ratio (M-H, Fixed, 95% CI)0.33 [0.01, 8.18]

    14.2 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    14.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.59]

 15 Maternal infection32150Risk Ratio (M-H, Fixed, 95% CI)0.88 [0.43, 1.82]

    15.1 Primiparous women
31617Risk Ratio (M-H, Fixed, 95% CI)0.81 [0.38, 1.72]

    15.2 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.59]

 16 Maternal mortality31740Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.61]

 17 Suboptimal or abnormal fetal heart trace (second stage of labour)1567Risk Ratio (M-H, Fixed, 95% CI)1.15 [0.89, 1.48]

 18 Admission to special care baby unit/neonatal intensive care unit52686Risk Ratio (M-H, Fixed, 95% CI)1.08 [0.77, 1.50]

    18.1 Primiparous women
52153Risk Ratio (M-H, Fixed, 95% CI)1.10 [0.78, 1.54]

    18.2 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)0.75 [0.17, 3.33]

 19 Suboptimal or abnormal fetal heart trace (first stage of labour)41284Risk Ratio (M-H, Fixed, 95% CI)1.09 [0.97, 1.23]

 20 Meconium aspiration syndrome21615Risk Ratio (M-H, Fixed, 95% CI)3.06 [0.83, 11.27]

    20.1 Primiparous and multiparous women
1925Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.61, 14.82]

    20.2 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)3.36 [0.14, 81.24]

    20.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.59]

 21 Acidosis as defined as a cord blood arterial pH of < 7.221014Risk Ratio (M-H, Fixed, 95% CI)1.18 [0.80, 1.73]

 22 Perinatal death83397Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.59]

    22.1 Primiparous women
72733Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    22.2 Primiparous and multiparous women
164Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    22.3 Multiparous women
2600Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.12, 73.59]

 23 Neonatal jaundice53202Risk Ratio (M-H, Fixed, 95% CI)0.90 [0.76, 1.06]

    23.1 Primiparous women
31614Risk Ratio (M-H, Fixed, 95% CI)1.16 [0.83, 1.62]

    23.2 Multiparous women
21065Risk Ratio (M-H, Fixed, 95% CI)0.83 [0.67, 1.02]

    23.3 Primiparous and multiparous women
2523Risk Ratio (M-H, Fixed, 95% CI)0.76 [0.42, 1.36]

 24 Seizures (neonate)54069Risk Ratio (M-H, Fixed, 95% CI)0.88 [0.15, 5.35]

    24.1 Primiparous women
42545Risk Ratio (M-H, Fixed, 95% CI)0.88 [0.15, 5.35]

    24.2 Multiparous women
21065Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    24.3 Primiparous and multiparous women
1459Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

 25 Respiratory distress syndrome21149Risk Ratio (M-H, Fixed, 95% CI)0.20 [0.01, 4.16]

    25.1 Primiparous and multiparous women
1459Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    25.2 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    25.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)0.20 [0.01, 4.16]

 26 Fracture1925Risk Ratio (M-H, Fixed, 95% CI)3.01 [0.31, 28.80]

 27 Intracranial haemorrhage1459Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

 28 Cephalhaematoma31712Risk Ratio (M-H, Fixed, 95% CI)1.52 [0.81, 2.83]

    28.1 Primiparous and multiparous women
21022Risk Ratio (M-H, Fixed, 95% CI)1.63 [0.86, 3.10]

    28.2 Primiparous women
1157Risk Ratio (M-H, Fixed, 95% CI)0.37 [0.02, 9.03]

    28.3 Multiparous women
1533Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

 
Comparison 2. Sensitivity analysis excluding trials with inadequate allocation concealment (c)

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

 1 Length of first stage of labour51127Mean Difference (IV, Random, 95% CI)-21.73 [-53.36, 9.91]

    1.1 Primiparous women
4379Mean Difference (IV, Random, 95% CI)-54.62 [-161.77, 52.52]

    1.2 Multiparous women
3386Mean Difference (IV, Random, 95% CI)23.47 [-46.14, 93.08]

    1.3 Primiparous and multiparous women
1362Mean Difference (IV, Random, 95% CI)-0.30 [-1.13, 0.53]

 2 Caesarean section84331Risk Ratio (M-H, Fixed, 95% CI)1.27 [0.98, 1.63]

    2.1 Primiparous women
52517Risk Ratio (M-H, Fixed, 95% CI)1.13 [0.86, 1.49]

    2.2 Multiparous women
1940Risk Ratio (M-H, Fixed, 95% CI)3.11 [0.66, 14.56]

    2.3 Primiparous and multiparous women
3874Risk Ratio (M-H, Fixed, 95% CI)2.36 [0.99, 5.63]

 3 Apgar score less than 7 at 5 minutes52908Risk Ratio (M-H, Fixed, 95% CI)0.51 [0.26, 0.98]

    3.1 Primiparous women
32385Risk Ratio (M-H, Fixed, 95% CI)0.42 [0.20, 0.88]

    3.2 Primiparous and multiparous women
2523Risk Ratio (M-H, Fixed, 95% CI)1.30 [0.26, 6.43]

 
Comparison 3. Amniotomy vs no amniotomy (dysfunctional labour)

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

 1 Caesarean section139Risk Ratio (M-H, Fixed, 95% CI)0.95 [0.15, 6.08]

    1.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)0.95 [0.15, 6.08]

 2 Maternal satisfaction with childbirth experience139Mean Difference (IV, Random, 95% CI)22.0 [2.74, 41.26]

 3 Apgar score less than 7 at 5 minutes139Risk Ratio (M-H, Fixed, 95% CI)2.86 [0.12, 66.11]

    3.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)2.86 [0.12, 66.11]

 4 Use of pain relief - epidural/narcotic139Risk Ratio (M-H, Fixed, 95% CI)1.48 [0.85, 2.57]

    4.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)1.48 [0.85, 2.57]

 5 Oxytocin augmentation139Risk Ratio (M-H, Fixed, 95% CI)0.87 [0.52, 1.47]

    5.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)0.87 [0.52, 1.47]

 6 Instrumental vaginal birth139Risk Ratio (M-H, Fixed, 95% CI)1.27 [0.33, 4.93]

    6.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)1.27 [0.33, 4.93]

 7 Caesarean section for fetal distress139Risk Ratio (M-H, Fixed, 95% CI)2.86 [0.12, 66.11]

    7.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)2.86 [0.12, 66.11]

 8 Caesarean section for prolonged labour139Risk Ratio (M-H, Fixed, 95% CI)0.48 [0.05, 4.82]

    8.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)0.48 [0.05, 4.82]

 9 Maternal mortality139Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

 10 Admission to special care baby unit/neonatal intensive care unit139Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]

    10.1 Primiparous and multiparous women
139Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]