Role of urethral electromyography in predicting outcome of Burch retropubic urethropexy

OBJECTIVE: To establish preoperative urethral electromyographic parameters that predict which women are unlikely to be cured of genuine stress inconti nence by Burch retropubic urethropexy procedures. STUDY DESIGN: Eighty-nine women who underwent preoperative urodynamic testi ng with urethral electromyography and retropubic urethropexy for genuine st ress incontinence were prospectively studied. Raw electromyographic signals were processed by an electromyographic instrument equipped with automated motor unit analysis software programs. Quantitative electromyographic softw are was used to analyze the electrical activity of the urethral sphincter w ith use of mean rectified voltage (MRV)-mean amplitude calculated over the entire tracing after the waveform is rectified-with women at rest and durin g voluntary urethral squeezing, repetitive coughing, and bladder filling, O bjective outcomes were determined 3 months after the operation with single- channel cystometrograms performed while subjects were standing. Nonparametr ic statistical analyses included the chi (2) test of association for nomina l data and the Mann-Whitney test for comparison of population medians. RESULTS: All women had urethral hypermobility and met our standard clinical criteria for retropubic urethropexy. Fifteen women had incomplete follow-u p data and were excluded from final analysis. Fifty-nine of 74 women (80%) were objectively cured, and 15 women had persistent genuine stress incontin ence. Women who were cured did not differ from those who were not cured in age, parity, menopausal status, maximum urethral closure pressure, Valsalva leak point pressure, maximum cystometric capacity, detrusor instability, o r prolapse stage. Women with persistent genuine stress incontinence were mo re likely to have had previous pelvic operations (P = .01). There were no d ifferences in any electromyographic parameters at rest, with urethral squee zing, or during bladder filling between the groups. Women who were objectiv ely cured had larger MRV values with repetitive coughing (P = .05) and larg er increases from resting MRV values (Delta MRV) with repetitive coughing ( P = .04). Twenty-seven of 30 women with MRV values greater than or equal to 25 muV with repetitive coughing were cured (positive predictive value [PPV ] = 90%; negative predictive value [NPV] = 32%), and 22 of 24 women with mo re than a 10-muV increase in resting MRV values with repetitive coughing (D elta MRV > 10 muV) were cured (PPV = 92%; NPV = 29%). If women had both an MRV value greater than or equal to 25 muV and a Delta MRV value > 10 PV, th e PPV was 100%; however, the NPV remained at 30%. CONCLUSION: Women who were cured of genuine stress incontinence with Burch retropubic urethropexy procedures had better motor unit action potential ac tivation with repetitive coughing than women with persistent genuine stress incontinence. Urethral electromyography may be used to assess the neuromus cular integrity of the striated urethral sphincter and to help predict whic h women will have successful retropubic urethropexy procedures.