Effect of Pre-operative Tizanidine on Postoperative Urinary Retention After Sacrospinous Vaginal Vault Suspension: a Pilot Study

Postoperative urinary retention has been defined as the inability to void despite having fluid in the bladder during the postoperative period. Urinary retention after pelvic reconstructive surgery requiring indwelling catheter or self-catheterization usage occurs in approximately 30-60% of patients postoperatively. Our prior retrospective chart review reviewing postoperative urinary retention rates after pelvic reconstructive surgery demonstrated postoperative urinary retention after a sacrospinous vaginal vault suspension to be approximately 78.9%.

Each patient after surgery undergoes a "voiding trial" where their voided volume is compared to their post-void residual volume. "Passing" a voiding trial has traditionally been defined as voiding a greater volume than the post-void residual volume. If the patient does not "pass" the voiding trial, the patient is characterized as having postoperative urinary retention and is discharged home with an indwelling catheter to prevent detrusor injury from bladder over-distention, pain and urinary tract infection.

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. Indwelling catheters are the leading cause of hospital-acquired urinary tract infections (UTIs), are often a source of embarrassment and inconvenience for patients, and often require additional office visits and healthcare utilization.

The leading hypotheses regarding the incidence of postoperative urinary retention after sacrospinous ligament suspension includes postoperative pain and pelvic floor muscle spasm leading to retention. The sacrospinous suspension includes a suture that is passed through the sacrospinous ligament and, therefore, through the coccygeus muscle with irritation of the pudendal nerve. The pelvic floor is a synergistic team of muscles that work together to support the pelvic organs and spasm of the coccygeus muscle, rather than an isolated muscle, can cause spasm of the entirety of the pelvic floor leading to retention. Tizanidine is a muscle relaxant which can work to alleviate this spasm and, theoretically, prevent postoperative urinary retention. Tizanidine also works as an alpha-adrenergic receptor blocker which can increase smooth muscle relaxation around the urethra specifically and, theoretically, improve urine flow.

Tizanidine is also frequently given for postoperative pain after sacrospinous ligament suspension and may act as an adjunct to a non-narcotic pain regimen to improve postoperative pain while reducing narcotic use after surgery. Postoperative buttock and posterior thigh pain are common symptoms after SSLF, with immediate pain reported in 6-84% of patients and persistent pain at 6 weeks occurring in 1-15%. Untreated acute postoperative pain has been shown to lead to increased morbidity and mortality. Pain is the most common reason for a postoperative unplanned hospital admission and poor postoperative pain control can lead to decreased ambulation, increased incidence of thromboembolism, and decreased inspiratory effort leading to postoperative pneumonia, therefore postoperative pain control is critical. In a country with rising narcotic-use and dependence, it is critical that we continue to explore non-narcotic alternatives for patients after surgery.