Kettle 2002.

Methods	RCT. Factorial 2 x 2 design.
Participants	Setting ‐ University Hospital of North Staffordshire, UK. 1542 women randomised. Inclusion criteria ‐ women who had a spontaneous vaginal delivery with a second‐degree tear or episiotomy, who had given their preliminary informed consent. Exclusion criteria ‐ instrumental vaginal delivery; extensive perineal trauma beyond the midwife's scope of practice; previous perineal surgery other than primary repair after childbirth; delivery of a stillborn infant or baby with extensive congenital abnormalities; women with AIDS or hepatitis B virus infection, severe perineal warts or extensive varicose veins of the genital area; women who were younger than 16 years and those unable to read, write or understand English language. Parity ‐ primigravida and multigravida. Mean age ‐ intervention group = 27.3; comparison group = 27.1. Operators ‐ midwives (n = 150) (29 women sutured by a doctor).
Interventions	Method of repair ‐ described as below. Intervention group (n = 772) ‐ un‐dyed fast‐absorbing polyglactin 910 (Vicryl Rapide) 2/0 on a 35 mm tapercut needle (50% had vaginal trauma, perineal muscle and skin repaired with a continuous non‐locking suture technique and 50% had vaginal trauma repaired with a locking continuous stitch; perineal muscle and skin sutured using the interrupted method). Comparison group (n = 770) un‐dyed standard polyglactin 910 (Vicryl) on a 35 mm tapercut needle (50% had vaginal trauma, perineal muscle and skin repaired with a continuous non‐locking suture technique and 50% had vaginal trauma repaired with a locking continuous stitch; perineal muscle and skin sutured using the interrupted method).
Outcomes	Short‐term pain ‐ day 2 and 10. Pain when walking, sitting, passing urine, opening bowels at 10 days. Analgesia ‐ day 10. Long‐term pain ‐ 3 months and 12 months. Dyspareunia ‐ 3 and 12 months. Removal of suture material and resuturing before 3 months; sutures uncomfortable; sutures tight; wound gaping; satisfaction with the repair and feeling back to normal within 3 months of birth.
Notes	Treatment envelopes were packed by Birmingham Clinical Trials Unit (envelopes contained 2 packets of masked suture material and instructions for method of repair on different coloured cards). Concealed interim analysis after 400 women entered the trial. Ethics Committee Approval. 9 women with a third degree tear and 1 with a fourth degree tear were recruited in error but were included in the analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	By external trials unit ‐ computer‐generated random permuted block with block size of 20 (5 of each treatment combination).
Allocation concealment?	Low risk	Serially numbered, sealed opaque envelopes
Blinding? Women	Low risk	The suture material was masked at source (suture material looked the same).
Blinding? Clinical staff	Low risk	The suture material was masked at source (suture material looked the same, packed in identical packets and coded to prevent identification). (Not possible to blind the suturing technique.)
Blinding? Outcome assessors	Low risk	The suture material was masked at source (suture material looked the same, packed in identical packets and coded to prevent identification).
Incomplete outcome data addressed? All outcomes	Low risk	Only 3 women did not complete a questionnaire at day 10. Response rate high at each time‐point throughout the study. One envelope unaccounted for. 96.7% response rate at 3 months and 90% at 12 months.
Free of other bias?	Low risk	No other bias apparent; most women received suture material according to randomisation group.