Two Intraoperative Techniques for Midurethral Sling Tensioning: A Randomized Controlled Trial

OBJECTIVE: To evaluate whether the use of a Mayo Scissor as a suburethral spacer compared with a Babcock clamp holding a loop of tape under the urethra results in different rates of abnormal bladder outcomes 12 months after retropubic midurethral sling surgery. METHODS: The MUST (Mid-Urethral Sling Tensioning) trial was a block-randomized, double-blind, multicenter clinical trial that allocated women to have their retropubic midurethral slings tensioned by Scissor or Babcock technique. The primary outcome (abnormal bladder) was a composite of persistent stress urinary incontinence (SUI), overactive bladder, and urinary retention. Secondary outcomes included outcomes of the composite, postoperative catheterization, incontinence-related questionnaires, repeat incontinence treatment, and uroflowmetry. Sample size of 159 in each arm (N=318) was planned for a superiority trial, hypothesizing a 10% difference in primary outcome. RESULTS: From September 2015 to December 2017, 506 women were screened and 318 were randomized. Baseline characteristics were similar in each arm. At 12 months, 253 (79.6%) women provided information on primary outcome: 40 of 128 (31.3%) patients with midurethral slings tensioned by Scissor experienced abnormal bladder, compared with 23 of 125 (18.4%) of those with midurethral slings tensioned by Babcock (P=.018, relative difference 12.9%). Secondary analyses favored Babcock for median duration of catheterization and the proportions of women experiencing urinary retention requiring sling lysis. Uroflowmetry parameters suggest the Scissor technique is more restrictive. Rates of mesh erosion were lower for the Scissor arm. No differences occurred in proportions of women experiencing patient reported persistent SUI after surgery. CONCLUSION: Abnormal bladder outcomes were 12.9% less frequent for women with midurethral slings tensioned by Babcock. Both techniques provided a comparable patient reported cure for SUI at 12 months. Women with midurethral slings tensioned by Scissors experienced more intervention for obstruction, whereas those with midurethral slings tensioned by Babcock experienced higher rates of mesh erosion. This information about how the postoperative courses differ allows surgeons to better counsel patients preoperatively or tailor their choice of technique. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02480231. FUNDING SOURCE: Boston Scientific.