Al Inany 2002.

Methods	Randomised controlled trial. 2:1 randomisation (drain: no drain).
Participants	120 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.
Interventions	Treatment 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).
Outcomes	Wound 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.
Notes	Trial conducted in Egypt 1999 to 2000.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No 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 risk	Not mentioned, assumed not done.
Blinding (performance bias and detection bias) Clinicians: surgeons and midwives	High risk	Not possible.
Blinding (performance bias and detection bias) Outcome assessment	Unclear risk	No information.
Incomplete outcome data (attrition bias) All outcomes	Low risk	We have assumed that the two women "excluded from the study" had been randomised. 120 randomised, outcome data for 118.
Other bias	Low risk