FEMALE UROLOGY

Urodynamically defined stress urinary incontinence and bladder outlet obstruction coexist in women
Bradley CS, Rovner ES
Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City, USA
J Urol. 2004; 171 (2 Pt 1): 757-60

• Purpose: The definition and significance of female bladder outlet obstruction (BOO) are poorly understood. We identified patients with urodynamic evidence of BOO in a cohort of women with stress urinary incontinence (SUI).
• Materials and Methods: Women with SUI were identified from a videourodynamic data base and pressure flow studies were reexamined. Subjects were excluded if detrusor pressures could not be measured. BOO was diagnosed if the maximum flow rate was less than 12 ml per second and detrusor pressure at maximum flow was greater than 20 cm water or maximum detrusor pressure was greater than 20 cm water in those without measurable flow. Clinical and urodynamic characteristics were compared in the obstructed and unobstructed groups.
• Results: Of 104 eligible subjects 19 (18.3%) had BOO. Maximum flow rate, mean flow rate and voided volume were significantly less in the BOO group than in the unobstructed group (8.7 vs. 13.5 ml per second, p = 0.004, 5.9 vs. 7.9 ml per second, p = 0.001 and 180 vs. 272 ml, p = 0.008). Detrusor pressure at maximum flow, maximum detrusor pressure and post-void residual volume were significantly greater in the BOO group than in the unobstructed group (28 vs. 15 cm water, p < 0.0001, 31 vs. 19 cm water, p < 0.0001 and 71 vs. 10 ml, p = 0.008). Etiologies of BOO identified in the 19 subjects included prior anti-incontinence or prolapse surgery in 6, neurological conditions in 4, cystocele in 2, dysfunctional voiding in 3 and idiopathic in 5.
• Conclusions: SUI and BOO can coexist even in the absence of common causes of obstruction.
  
  
• Editorial Comment
  The authors of this study reviewed their video urodynamic database and analyzed women with stress urinary incontinence (SUI) to identify evidence of bladder outlet obstruction. It was found that of 104 female patients with urodynamic stress urinary incontinence (defined as involuntary leakage from the urethra during increased abdominal pressure in the absence of a detrusor contraction), 19 (18.3%) had bladder outlet obstruction (BOO). Bladder outlet obstruction was diagnosed if there was a maximum flow rate of < 12 cc/sec and a detrusor pressure at maximum flow of > 20 cm, or if no measurable flow was identified that there was a sustained detrusor contraction during the attempt to void of > 20 cm of water. Potential etiologies of bladder outlet obstruction were identified in 14 of the 19 patients including prior surgery, neurological disorder, cystocele, and dysfunctional voiding. Idiopathic etiology was noted in 5 of the 19 patients.
  This paper carries a true intrinsic value through its demonstration that stress urinary incontinence and bladder outlet obstruction may synchronously coexist. Critical points of this study do include the notation that patients were standing during the voiding portion of the urodynamic study as opposed to the standard female micturitional sitting position. The effect of this different position on gender specific voiding is unclear. In addition, the pressure flow analysis was completed with a catheter in the bladder as opposed to a catheter free uroflow. Groutz et al. (1) have previously discussed the potential effect of a transurethral catheter on maximum flow rates in obstructed females. One may postulate that perhaps if the patients in this data base had a catheter free uroflow they would not have qualified as obstructed in this study.
  The authors highlight the expanding interest in the identification and analysis of bladder outlet obstruction in women. This will especially have great value for the surgeons who must re-operate on patients who have failed a previous anti-incontinence operation and ponder the need to include a formal urethrolysis at the re-operative setting.

Reference
1. Groutz A, Blaivas JG, Sassone AM: Detrusor pressure uroflowmetry studies in women: effect of a 7Fr
transurethral catheter. J Urol. 2000; 164: 109-14.

Dr. Steven P. Petrou
Associate Professor of Urology
Mayo Clinic College of Medicine
Jacksonville, Florida, USA