FEMALE UROLOGY

Preoperative urodynamic evaluation may predict voiding dysfunction in women undergoing pubovaginal sling
Miller EA, Amundsen CL, Toh KL, Flynn BJ, Webster GD
Department of Urology, University of Washington Medical Center, Seattle, Washington, USA
J Urol. 2003; 169: 2234-7

• Purpose: We determine which urodynamic parameters can best predict postoperative voiding dysfunction following pubovaginal sling surgery.
• Materials and Methods: The records of 98 consecutive women who had undergone pubovaginal sling surgery with allograft fascia lata between July 1998 and July 2000 were reviewed. Urodynamic and follow-up data were sufficient for evaluation for 73 patients. Urodynamic and clinical parameters were correlated with urinary retention, time to return of efficient voiding and development of post-operative urgency symptoms.
• Results: Average time to return of efficient voiding was 3.92 days (median 3). Of 21 women who voided without a detrusor contraction, urinary retention developed in 4 (23%) versus 0 of 48 who voided with detrusor contraction (p = 0.007). Urinary retention was defined as the need to perform even occasional self-catheterization. All 4 women with urinary retention had a detrusor pressure of greater than 12 cm H20 (0 in 3, 4 in 1). None of the women with a detrusor pressure of greater than 12 cm H2O had urinary retention (p = 0.047). The presence of Valsalva voiding in women without detrusor contraction did not affect the incidence of urinary retention (11.1%) compared to those who did not demonstrate Valsalva voiding (5.1%) (p = 0.603). Peak flow rate, detrusor instability on preoperative urodynamics and post-void residual urine volume were not associated with postoperative urinary retention. Finally, post-void residual urine volume predicted delayed return to normal voiding (p = 0.001). There were no other urodynamic parameters that were significantly associated with urinary retention, delayed return to normal voiding or postoperative urgency symptoms including peak flow rate, capacity or compliance.
• Conclusions: Women who void without or with a weak detrusor contraction are most likely to have urinary retention postoperatively. Therefore, we conclude that preoperative urodynamic evaluation may be used to counsel women regarding the risk of urinary retention following the pubovaginal sling procedure.
  
• Editorial Comment
  The authors review the urodynamic parameters and follow-up data on 73 patients who had undergone pubovaginal sling with allograft fascia lata. They characterized post-operative dysfunctional voiding patterns as urinary retention, delayed return to normal voiding and de novo urgency. The urodynamic patterns analyzed to define post-operative dysfunctional voiding patterns included detrusor voiding pressure at maximum flow rate, detrusor instability, peak flow rate, post-void residual, cystometric bladder capacity and bladder compliance. Out of the 73 post-operative women reviewed, 4 women were in urinary retention and 9 different women took greater than 7 days to resume their post-operative voiding. The 4 women in urinary retention all voided without a detrusor contraction. One of those women voided with Valsalva maneuvers while the other three in urinary retention voided without a Valsalva maneuver. Of the 7 women who were noted to void by Valsalva maneuver, one had a delayed return to efficient voiding. Three patients developed de novo urgency and one of the three had detrusor instability on pre-operative urodynamics while two did not.
  This paper is quite notable with regard to emphasizing the importance of pre-operative urodynamic evaluation prior to an anti-incontinence procedure and to commenting on the post-operative voiding function of Valsalva voiders. Many times with a physical examination and history consistent with stress urinary incontinence, surgeons will question the need to put patients through a urodynamic testing. The value of a urodynamic testing denoted by this article would include characterizing the woman’s voiding pattern with regards to the use of a detrusor contraction or not, in addition to documenting detrusor instability. Preparation for potential post-operative difficulties is of immeasurable value in the field of voiding dysfunction. However, as stated by this paper, most women who void without a detrusor contraction will not have urinary retention after an anti-incontinence operation such as a sling. Perhaps these patients do normally void with a detrusor contraction but that the urodynamic study was unable to identify or characterize same thus obscuring the true voiding difficulties of patients who void without a detrusor contraction and who undergo a suburethral sling.

Dr. Steven P. Petrou
Associate Professor of Urology
Mayo Medical School
Jacksonville, Florida, USA