Purpose To test the hypothesis that advanced stages of pelvic organ prolapse can result in a functional obstruction of the urethra, we studied the effects of manual prolapse reduction on urodynamic and urethral electromyographic parameters in women with stage III and IV pelvic organ prolapse. Materials and Methods Women with advanced pelvic organ prolapse undergoing clinical multichannel urodynamics with concentric needle electromyography of the urethra were invited to participate in this institutional review board approved study. Women underwent filling cystometry and electromyography with prolapse everted and with prolapse reduced. Women were randomized to cystometry order (reduced vs everted). All subjects underwent a third study with prolapse reduction. Maximum urethral closure pressure and quantitative electromyography of the striated urethral sphincter were determined at maximum cystometric capacity. During the pressure flow study voiding parameters, including urethral electromyography quieting, were determined. The nonparametric paired sign test was used to evaluate differences in urodynamic parameters and quantitative electromyography with pelvic organ prolapse reduced and unreduced. Results were considered significant at the 5% level. Results The 31 participants had mean age of 60 years (range 36 to 78) and 83% were white. There were no clinically significant differences in maximum cystometric capacity, voided volume, maximal flow and detrusor pressure at maximal flow or time to maximal flow between the reduced and everted prolapse states. Prolapse reduction resulted in a clinically and statistically significant decrease in maximum urethral closure pressure (−31%) but it had no impact on quantitative urethral electromyography. Conclusions These findings demonstrate that, although prolapse reduction significantly decreases maximum urethral closure pressure, it does not alter intrinsic neuromuscular activity of the striated urethral sphincter. Prolapse reduction does not alter any other filling or pressure flow parameter.