(Poster 126) Effect of Tizanidine on POUR After Sacrospinous Ligament Fixation: A Pilot Study

Objectives: Postoperative urinary retention (POUR) has been defined as the inability to void despite having fluid in the bladder during the postoperative period (1). Urinary retention after pelvic reconstructive surgery requiring indwelling catheter or self-catheterization usage occurs in approximately 30-60% of patients postoperatively (1,2,3). Our prior retrospective chart review demonstrated the rate of POUR after a sacrospinous ligament fixation (SSLF) to be approximately 78.9%. Many women consider being discharged home with a Foley catheter to be a surgical complication and describe catheter use as the worst aspect of their surgery and can lead to UTIs and increased healthcare utilization (1,6,7). The leading hypotheses regarding the incidence of POUR after SSLF includes postoperative pain and pelvic floor muscle spasm leading to retention. Tizanidine is a muscle relaxant which can work to alleviate this spasm and, theoretically, prevent postoperative urinary retention (8). Tizanidine is a low-risk, well tolerated, cost-effective medication (8). No study to date has evaluated preoperative administration of tizanidine for POUR. We hypothesize that providing tizanidine preoperatively will improve POUR compared with our previously defined baseline data after SSLF.

Methods: Women who presented to our tertiary urogynecology clinic with pelvic organ prolapse planning to undergo SSLF were invited to participate in this study. Patients were enrolled to receive a single preoperative dose of tizanidine 2mg in the preoperative holding area on the day of their scheduled surgery. We then evaluated the rate of POUR after administration of tizanidine compared with our previously studied and documented POUR incidence after SSLF. Based on a sample size calculation to achieve 80% power, to evaluate for a 50% decrease in POUR rate, we need 23 subjects total. Data was analyzed using SAS 9.4 (SAS Inc., Cary, NC). Demographic and clinical characteristics between groups were compared using Student t-test (parametric) or Mann-Whitney U test (nonparametric) for continuous variables and Chi-squared test or Fisher exact test for categorical variables.

Results: We are presenting our preliminary data for the 15 subjects that have completed the study to date with an average age of 68.5, with an average BMI of 27.3, primarily non-smoker (66.67%) and post-menopausal (93.3%). Nine patients (60%) underwent a concomitant mid-urethral sling placement and two subjects (13.3%) underwent concomitant hysterectomy. Regarding our primary study outcome, 9 subjects were diagnosed with POUR (60%).

Conclusions: Preoperative tizanidine administration prior to SSLF does not appear to reduce the incidence of POUR in these patients. The incidence of POUR appears to be especially high in patients undergoing this procedure. Further research should be dedicated to reducing the incidence of POUR in these patients to improve patient satisfaction and surgical experience.