To describe the prevalence of hydronephrosis in advanced pelvic organ prolapse (POP) and to describe clinical and urodynamic parameters associated with hydronephrosis.

Prospective, observational cohort study examining the prevalence of hydronephrosis in advanced POP. Women with a POP-Q examination of at least +1 for points C, Aa, or Ba were enrolled and screened for hydronephrosis. Basic demographics, clinical, and urodynamic findings among women with and without hydronephrosis were compared. The University of Southern California IRB approved this protocol.

A total of 180 participants were enrolled. Fifty-five women had some hydronephrosis, for a prevalence of 30.6% (24.3%-37.6%). Mean age was 57.9 (±9.0) years and mean body mass index was 29.2 kg/m² (± 4.6). Of the participants, 80.6% were postmenopausal. The presence of diabetes mellitus was significantly associated with hydronephrosis (8% without vs 21.8% with, P = .009), as was the degree of anterior and apical (median Aa, Ba, C, and D higher with hydronephrosis than without, P <.01) but not posterior POP (median Ap and Bp, P = .13, and .2, respectively). On multichannel urodynamics, participants with hydronephrosis had higher mean post void residuals (64.8 vs 38.5 mL, P = .007), lower mean first leak (199.6 vs 280.8 mL, P = .006), and higher mean maximum cystometric capacity (525.2 vs 476.7 mL, P = .02) compared with participants without hydronephrosis.

The prevalence of hydronephrosis in women with advanced POP is 30.6%. Clinical factors associated with hydronephrosis include degree of anterior or apical POP and diabetes mellitus. Urodynamic factors associated with hydronephrosis include elevated postvoid residuals, larger cystometric capacity, and lower volume at first leak.