Diagnosing bladder outlet obstruction in women

Purpose: There are no universally accepted urodynamic criteria for diagnosi ng female bladder outlet obstruction. When accepted criteria for men are ap plied to women, the diagnosis of obstruction may often be missed, which is most likely due to differences in voiding dynamics. We propose video urodyn amic criteria for diagnosing obstruction in women, and describe the urodyna mic findings in those with and without obstruction. Materials and Methods: We reviewed the charts of 331 women who underwent mu ltichannel video urodynamics for nonneurogenic voiding dysfunction. Of thes e women 261 (mean age 55.8 years) had evaluable voiding pressure flow studi es with simultaneous video fluoroscopy of the bladder outlet during voiding . At video urodynamics cases were classified as obstructed if there was rad iographic evidence of obstruction between the bladder neck and distal ureth ra in the presence of a sustained detrusor contraction. Strict pressure flo w criteria were not used. Maximum flow rate, detrusor pressure at maximum f low rate, post-void residual, bladder capacity and the incidence of detruso r instability were compared between obstructed and unobstructed cases. Results: A total of 76 women met the criteria for obstruction (mean age 57. 5 years), while 184 (mean age 55) did not. Causes of obstruction were dysfu nctional voiding in 25 cases, cystocele in 21, primary bladder neck obstruc tion in 12, iatrogenic from incontinence surgery in 11, urethral stricture in 3, uterine prolapse in 2, urethral diverticulum in 1 and rectocele in 1. Obstructed cases had lower mean maximum flow rate (9 versus 20.2 mi. per s econd, p <0.0001), higher mean detrusor pressure at maximum flow rate (42.8 versus 22.1 cm. water, p <0.0001) and higher mean post-void residual (157 versus 33 ml.,p <0.0001). There was no difference in bladder capacity (381 versus 347 mi.) or incidence of detrusor instability (45 versus 41%). Conclusions: Using the proposed video urodynamic criteria obstructed cases had significantly higher voiding pressures, lower flow rates and higher pos t-void residual than unobstructed cases, as expected. However, absolute val ues, especially for voiding pressure, are not as dramatic in women as in me n. Pressure flow studies alone may fail to diagnose obstruction but simulta neous imaging of the bladder outlet during voiding greatly facilitates diag nosis.