STUDY TYPE Therapy (meta-analysis) Level of Evidence 1a. OBJECTIVES To assess the effectiveness and complications of transobturator tape (inside-out and outside-in, TOT) by means of a systematic review of direct and indirect randomized controlled trials (RCTs). METHOD MEDLINE, EMBASE, CINAHL, LILIACS (up to December 2008), CENTRAL (The Cochrane Library, Issue 1, 2009), MetaRegister of Controlled Trials, The National Library for Health, the National Research Register and Google Scholar were searched using various relevant search terms. The citation lists of review articles and included trials were searched and contact with the Correspondence of each included trials was attempted. RCTs which compared the effectiveness of synthetic transobturator (inside-out tape TVTO, or outside-in TOT) with TVT by the retropubic route (Gynecare, Ethicon, Inc., or similar tape by a different company) or with each other for the treatment of stress urinary incontinence (SUI), and in all languages, were included. Two reviewers extracted data on participants' characteristics, study quality, intervention, cure and adverse effects independently. The data were analysed using Review Manager 5 software. RESULTS There were 12 RCTs that compared TOT with TVT, and 15 that compared TVTO vs TVT for treating SUI. There were four direct comparison RCTs of TVTO vs TOT. When compared at 1-44 months, the subjective (odds ratio 1.16; 95% confidence interval 0.83-1.6) and objective (0.94; 0.66-1.32) cure of TOT was similar to TVT. For TVTO, the subjective (1.06, 0.85-1.33) and objective cure (1.03, 0.77-1.39) was also similar to TVT. Adverse events such as bladder injuries (TOT, odds ratio 0.11, 0.05-0.25; TVTO, 0.15, 0.06-0.35) and haematomas (0.06, 0.01-0.30) were less in the TOT than TVT. Voiding difficulties (TOT, odds ratio 0.61, 0.35-1.07); TVTO, 0.81, 0.48-1.31) were slightly lower in TOT but this was not statistically significant. Groin/thigh pain (TVTO, odds ratio 8.05, 3.78-17.16) and vaginal injuries (TOT, 5.82, 1.85-18.3; TVTO, 1.69, 0.73-3.91) were more common in the transobturator tapes. Mesh erosion in TVTO (0.77, 0.22-2.72) and TOT (1.11, 0.54-2.28) was similar to TVT. The effectiveness data over 6 months available from four direct comparison studies of TVTO vs TOT suggested equivalent results for objective cure (1.06, 0.65-1.73) and subjective cure (1.37, 0.93-2.00). When compared indirectly, TVTO has similar subjective (1.23, 0.83-1.82) and objective cure (0.97, 0.62-1.52) to TOT. On indirect comparison, the de novo risk of urgency was similar in the two groups but voiding difficulties seemed to be less in the inside-out group. CONCLUSION The evidence for the equivalent effectiveness of TOT and TVTO when compared with each other is established over the short-term. Bladder injuries and voiding difficulties seem to be less with inside-out tapes on indirect comparison. An adequate long-term follow-up of the RCTs is desirable to establish the long-term continued effectiveness of transobturator tapes.