Intervention Review

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Wound drainage for caesarean section

  1. Simon Gates1,*,
  2. Elizabeth R Anderson2

Editorial Group: Cochrane Wounds Group

Published Online: 13 DEC 2013

Assessed as up-to-date: 14 NOV 2013

DOI: 10.1002/14651858.CD004549.pub3


How to Cite

Gates S, Anderson ER. Wound drainage for caesarean section. Cochrane Database of Systematic Reviews 2013, Issue 12. Art. No.: CD004549. DOI: 10.1002/14651858.CD004549.pub3.

Author Information

  1. 1

    Division of Health Sciences, Warwick Medical School, The University of Warwick, Warwick Clinical Trials Unit, Coventry, UK

  2. 2

    Royal Liverpool University Hospital, Department of Genito-urinary Medicine, Liverpool, UK

*Simon Gates, Warwick Clinical Trials Unit, Division of Health Sciences, Warwick Medical School, The University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK. s.gates@warwick.ac.uk.

Publication History

  1. Publication Status: New search for studies and content updated (conclusions changed)
  2. Published Online: 13 DEC 2013

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Characteristics of included studies [ordered by study ID]
Al Inany 2002

MethodsRandomised controlled trial. 2:1 randomisation (drain: no drain).


Participants120 obese women undergoing caesarean section with a body mass index of more than 32.
80 women in the drain group and 40 women in the 'no drain' group.
2 women were excluded because they left the hospital after two days and did not complete follow-up.

Excluded if: pre-labour caesarean section; prolonged pre-labour rupture of membranes; prolonged labour; "long pre-operative hospitalisation"; chronic illness.
Included if: first or repeat caesarean; intrapartum caesarean.
All skin incisions were Pfannenstiel incisions.
No subcutaneous sutures were used.


InterventionsTreatment group: subcutaneous suction drain.
Control group: no subcutaneous drain.

Drains were left in for 24 hours or until the drainage was <50 ml (time period not specified).


OutcomesWound breakdown, wound haematoma and post-operative febrile morbidity (> 38.5C, >24 hours and < 5 days) incidence available on 118 women.
Wounds assessed prior to discharge, 5-7 days post-operatively and at 3 weeks.


NotesTrial conducted in Egypt 1999 to 2000.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNo information.

Allocation concealment (selection bias)Unclear risk"Participants were allocated using sealed envelopes" - numbering, opacity or method of using sealed envelopes not mentioned, not whether all envelopes were accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible.

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information.

Incomplete outcome data (attrition bias)
All outcomes
Low riskWe have assumed that the two women "excluded from the study" had been randomised. 120 randomised, outcome data for 118.

Other biasLow risk

Allaire 2000

MethodsRandomised controlled trial.
Randomisation during surgery after fat depth had been measured.


Participants76 women undergoing caesarean section with more than 2cm of subcutaneous fat.
24 women in the drain group and 52 women in the 'no drain' group.

Excluded if no time for adequate consent.
Included if: first or repeat caesarean; pre labour or intrapartum caesarean.
The type of skin incision was not described.


InterventionsTreatment group: subcutaneous drain.
Control group for this review: no subcutaneous drain (with or without closure of the subcutaneous tissue).

Three randomised groups: subcutaneous drain used; closure of subcutaneous tissue; no closure of subcutaneous tissue or use of subcutaneous drain.

Drains were "removed in 72 hours" or when drainage was <50 ml in 24 hours.


OutcomesWound infection and wound complication incidence available on all randomised women.
No loss to follow-up documented.

Wounds assessed prior to discharge and at staple removal (7 to 10 days post-partum). Further complications identified by retrospective chart review (timing not stated).


NotesTrial conducted in USA 1995 to 1997. 1109 women delivered by caesarean section; 76 enrolled in the study.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated.

Allocation concealment (selection bias)Unclear riskNumbers kept in opaque sealed envelopes. No information on whether all envelopes were accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible.

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information.

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo losses documented.

Selective reporting (reporting bias)Unclear riskNo information.

Other biasLow risk

CAESAR 2010

MethodsRandomised controlled 2x2x2 factorial trial. Comparisons were: 1. single- versus double-layer closure of the uterine incision; 2. closure versus nonclosure of the pelvic peritoneum; 3. liberal versus restricted use of a sub rectus sheath drain.

2827 women randomised to the liberal versus restricted drainage comparison.


ParticipantsWomen having first caesarean section; uterine incision via lower segment; age 16 years or over.

1414 randomised to liberal use of sub-sheath drain.

1413 randomised to restricted use of sub--sheath drain.


Interventionsliberal use of a sub-sheath drain; drain should be used unless there was an overriding clinical reason not to use it.

restricted use of a sub-sheath drain; drain should not be used unless there was an overriding reason to use it.


OutcomesPrimary outcome: maternal infectious morbidity, defined as having one or more of the following: (i) antibiotic use for maternal febrile morbidity during the postnatal hospital stay; (ii) endometritis; (iii) wound infection treated with antibiotics

Secondary outcomes: antibiotic use, endometritis, wound infection treated with antibiotics, further operative procedures on the wound, pain, blood transfusion, breastfeeding at hospital discharge and at 6 weeks, other severe or unexpected maternal morbidity.


NotesWound drain was used in 63% of women allocated to liberal use, and 6% of women allocated to restricted use.

Primary outcome was changed during recruitment from febrile morbidity/endometritis to infectious morbidity, because of low incidence of the original primary outcome.

Trial conducted in UK and Italy, 2000 to 2006.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated sequence.

Allocation concealment (selection bias)Low riskRemote telephone randomisation system with minimisation for participating centre; ‘in labour’ or ‘not in labour’; single or multiple pregnancy.

Blinding (performance bias and detection bias)
Women
High riskAlthough trial report states that women were unaware of the allocations used, they would probably have been aware of whether they had a drain or not.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible to blind clinicians.

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskOutcomes recorded from hospital notes; therefore likely that they could have been recorded with knowledge of allocations.

Incomplete outcome data (attrition bias)
All outcomes
Low riskRandomisation before the start of surgery, hence 30 women excluded because they did not deliver by caesarean section, and 2 excluded because they withdrew consent prior to surgery..

Approx 10% loss to follow-up for outcomes at 6 weeks.

Selective reporting (reporting bias)Low riskOUtcomes reported are specified in the study protocol.

Other biasLow risk

Kumar 2004

MethodsRandomised controlled trial. Randomisation during surgery. Outcomes measured at 2 and 6 weeks.


Participants148 women requiring caesarean section with >2cm subcutaneous fat (measured during surgery). 46 in the drain group and 102 in the no drain group.

No exclusions mentioned.


InterventionsTreatment group: subcutaneous drain.
Control group for this review: no subcutaneous drain (with or without closure of the subcutaneous tissue).

Randomisation was to three groups: 1. subcutaneous drain; 2. subcutaneous stitch; 3. neither drain nor stitch. Groups 2 and 3 combined for the review to give a comparison of drain versus no drain.


OutcomesPost-operative febrile morbidity, wound infection, wound complications. operative procedures on wound, duration of postnatal hospital stay.


Notes


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated random sequence.

Allocation concealment (selection bias)Unclear riskSealed envelopes opened in operating theatre after closure of rectus sheath. No mention of numbering or accounting for all envelopes.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed no blinding.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible.

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information.

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo missing data.

Selective reporting (reporting bias)Unclear riskNo information.

Other biasLow risk

Loong 1988

MethodsRandomised controlled trial.
Randomisation during surgery.


Participants400 women undergoing caesarean section; unclear how many randomised.
262 women included, 138 women excluded.
193 women in the drain group and 69 women in the 'no drain' group.

Excluded if: pre-existing pyrexia; prophylactic antibiotics.
Included if: first or repeat caesarean; pre labour or intrapartum caesarean.
Obesity unspecified.
All skin incisions were Pfannenstiel incisions.


InterventionsTreatment group: drain used (subcutaneous or sub-rectus).
Control group: no drain.

Four randomised groups: subcutaneous drain used; sub-rectus sheath drain used; both drains used; no drain used.
Drains left in for >6 hours and <36 hours.


OutcomesWound infection and febrile morbidity incidence available on 262 women.
No loss to follow-up documented.

Timing of wound assessment not recorded.


NotesTrial conducted in Hong Kong 1986.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskRandom numbers

Allocation concealment (selection bias)Unclear riskNo information on how random numbers were used to perform allocations

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo losses to follow-up mentioned.

Other biasLow risk

Magann 2002

MethodsRandomised controlled trial.
Randomisation by computer generated random number sequence.


Participants590 women undergoing caesarean section were deemed eligible intraoperatively because they had more than 2cm of subcutaneous fat.
964 women undergoing caesarean section were however randomised preoperatively.
194 women in the drain group and 396 women in the 'no drain' group

Excluded if: no time for adequate consent; less than 2cm of subcutaneous fat (when measured intraoperatively).
Included if: first or repeat caesarean; pre labour or intrapartum caesarean; vertical or transverse skin incision.


InterventionsTreatment group: subcutaneous drain used.
Control group for this review: no subcutaneous drain (with or without subcutaneous tissue closure).

Three randomised groups: subcutaneous drain used; closure of subcutaneous tissue; no closure of subcutaneous tissue or use of subcutaneous drain.

The timing of drain removal was not documented.


OutcomesWound infection, wound complication and endometritis incidence available on all randomised women at staple removal (7 to 10 days post-partum).
Mean blood loss and mean duration of operation also available.

Unclear at which point in the follow-up period the recorded outcomes were diagnosed.


NotesTrial conducted in USA 1998 to 2001.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated random numbers

Allocation concealment (selection bias)Unclear riskNumbers kept in opaque envelopes. No information on whether all envelopes were accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo losses to follow-up documented up to discharge from hospital.

Selective reporting (reporting bias)Unclear riskNo information.

Other biasHigh riskPre-operative randomisation means that 374 women were excluded post-randomisation because they did not fulfil the eligibility criteria (depth of subcutaneous tissue <2cm). Possible for this to introduce bias.

Maharaj 2000

MethodsRandomised controlled trial.


Participants440 women undergoing 'emergency' caesarean section.
217 women in the drain group and 223 women in the 'no drain' group
3 women from the 'no drain' group excluded because they required a drain. It is not clear whether these were included in the 223 or not.

Excluded if: elective caesarean section; vertical skin incision; existing intra-uterine infection; drain definitely required;
Included if: Pfannenstiel incision.
Not specified if first or repeat caesarean, or pre labour or intrapartum caesarean.


InterventionsTreatment group: subcutaneous drain and sub-rectus sheath drain.
Control group: no drains.

Drains removed at 48 hours or when drainage stopped.


OutcomesWound 'morbidity', haematoma, purulent discharge and wound dehiscence available on all randomised women at discharge or day 7.
Mean blood loss, mean duration of surgery and mean post-natal stay also recorded.


NotesTrial conducted in South Africa 1996 to 1997


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated random number sequence

Allocation concealment (selection bias)Unclear riskNumbers kept in opaque envelopes. No information on whether all envelopes were accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High risk

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo loss to follow-up documented at discharge from hospital

Selective reporting (reporting bias)Unclear riskNo information

Other biasLow risk

Ochsenbein-Imhof 2001

MethodsRandomised controlled trial.


Participants305 women undergoing caesarean section.
151 women in the drain group and 154 women in the 'no drain' group.

Excluded if: 'emergency' caesarean section; pre-eclampsia; bleeding diathesis; increased risk of bleeding; severe fetal deformity.
Included if: elective or intrapartum caesarean section.
Not specified if: first or repeat caesarean; obese or non-obese; transverse or vertical skin incision.


InterventionsTreatment group: subcutaneous and sub-rectus sheath suction drains.
Control group: no drains.

The timing of drain removal was not documented.


OutcomesWound haematoma, need for further surgery, mean amount of opiate analgesia, mean duration of surgery and mean duration of post-natal stay results available on all randomised women at discharge.

Wounds assessed at discharge (time-period not specified).


NotesTrial conducted in Switzerland 1998 to 1999


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNo information

Allocation concealment (selection bias)Unclear riskNumbers kept in opaque envelopes. No information on whether all envelopes were accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High risk

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo loss to follow-up documented at discharge from hospital

Selective reporting (reporting bias)Unclear riskNo information

Other biasLow risk

Ramsey 2005

MethodsRandomised controlled trial. Randomisation during surgery. Outcomes measured at 7-14 days post discharge and 4-6 weeks.


Participants280 women. Delivery by caesarean section, BMI >= 30 at admission, subcutaneous fat >=4cm (measured during surgery).
Exclusion criteria: 1. no consent; 2. moribund caesarean delivery; 3. no plan for postpartum care in recruiting centre.


InterventionsTreatment group: Subcutaneous suture plus drain (131 women)
Control group: subcutaneous suture only (149 women).


OutcomesWound complications, readmission to hospital.


NotesReport states that randomisation block size was 20 but there is a discrepancy of 18 between the numbers randomised to the two arms; this would be impossible with a block size of 20 unless there were patients missing from the analysis. Therefore we suspect that there are unreported post-randomisation exclusions.

Outcome data given as percentages not numbers, so there is doubt about exact numbers in some cases.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskComputer generated, block size = 20.

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

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not blinded.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible.

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNot mentioned.

Incomplete outcome data (attrition bias)
All outcomes
Low risk12 women (4.3%) did not have follow-up wound assessment (reasons not given).

Selective reporting (reporting bias)Unclear riskNo information

Other biasUnclear riskDiscrepancy of 18 in numbers randomised to each group despite block size of 20. Suggests that there may be women randomised to drain group missing.

Saunders 1988

MethodsRandomised controlled trial.


Participants200 women undergoing lower-segment caesarean section.
100 women in the drain group and 100 women in the 'no drain' group

Excluded if: drain definitely required;
Included if: first or repeat caesarean; pre labour or intrapartum caesarean.
All skin incisions were Pfannenstiel incisions.
Not specified if: obese or non-obese.


InterventionsTreatment group: sub-rectus sheath suction drain.
Control group: no drain.

Drains removed at 48 hours or when drainage stopped.


OutcomesWound haematoma, wound infection, mean number of analgesic doses and mean length of hospital stay available on all randomised women at discharge.

Wounds assessed at 2, 4 and 6 days post-operatively.


NotesTrial conducted in UK. Published in 1988.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskNot described.

Allocation concealment (selection bias)Low risk200 opaque sealed envelopes shuffled and stored in the operating theatre. All envelopes accounted for.

Blinding (performance bias and detection bias)
Women
High riskNot mentioned, assumed not done.

Blinding (performance bias and detection bias)
Clinicians: surgeons and midwives
High riskNot possible

Blinding (performance bias and detection bias)
Outcome assessment
Unclear riskNo information

Incomplete outcome data (attrition bias)
All outcomes
Low riskNo loss to follow-up documented at discharge from hospital

Selective reporting (reporting bias)Unclear riskNo information

Other biasLow risk

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Bose 2006abstract only, author contacted for further information, no response.

 
Comparison 1. Wound drain versus no drain

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

 1 Wound infection74377Risk Ratio (M-H, Fixed, 95% CI)1.02 [0.85, 1.21]

 2 Wound complications61640Risk Ratio (M-H, Random, 95% CI)0.85 [0.55, 1.32]

 3 Febrile morbidity63829Risk Ratio (M-H, Fixed, 95% CI)0.87 [0.66, 1.15]

 4 Postoperative pain1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 5 Blood loss (ml)21030Mean Difference (IV, Fixed, 95% CI)23.41 [-1.93, 48.74]

 6 Blood transfusion1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 7 Duration of surgery (mins)4Mean Difference (IV, Random, 95% CI)Totals not selected

 8 Duration of postnatal hospital stay (days)5Mean Difference (IV, Random, 95% CI)Totals not selected

 9 Readmission to hospital23064Risk Ratio (M-H, Fixed, 95% CI)1.08 [0.70, 1.66]

 10 Breastfeeding at hospital discharge1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 11 Postoperative analgesia1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 12 Endometritis23386Risk Ratio (M-H, Fixed, 95% CI)1.20 [0.90, 1.59]

 13 Operative procedures on wound1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 
Comparison 2. Subcutaneous drain versus sub-sheath drain

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

 1 Wound infection1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 2 Febrile morbidity1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 
Comparison 3. Wound drain versus subcutaneous suture

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

 1 Wound infection3533Risk Ratio (M-H, Fixed, 95% CI)0.77 [0.42, 1.44]

 2 Wound complications3533Risk Ratio (M-H, Random, 95% CI)0.56 [0.17, 1.87]

 3 Febrile morbidity1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 4 Blood loss1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 5 Duration of surgery (mins)1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 6 Duration of postnatal hospital (days)1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 7 Postoperative pain1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 8 Endometritis1Risk Ratio (M-H, Fixed, 95% CI)Totals not selected

 
Table 1. Pain outcomes in CAESAR 2010

Drain

(liberal use)
No drain

(restricted use)
P-value (rank sum test)

Hospital discharge20 (9-37)19 (8-34)0.2

6 weeks3 (0-11)2 (0-10)0.1