Risk factor analysis for postoperative urinary retention after surgery for degenerative lumbar spinal stenosis

Abstract

Background context: Postoperative urinary retention (POUR) may not be considered a major complication after surgery for degenerative lumbar spinal stenosis. However, improper management of transient POUR leads to bladder overdistension and permanent bladder detrusor damage. Systematic monitoring of POUR may be recommended in vulnerable patients.

Purpose: The aim of the present study was to determine the incidence of and risk factors for POUR.

Study design/setting: This is a retrospective nested case-control study.

Patient sample: A total of 284 consecutive patients (M : F=125:159; mean age, 63.3 years) who underwent spine surgery for degenerative lumbar spinal stenosis were reviewed.

Outcome measures: A multivariable logistic model was utilized to identify risk factors.

Methods: A systematic postoperative voiding care protocol was applied for all patients to monitor them for the development of POUR. An indwelling urethral catheter was inserted intraoperatively and removed in the postanesthesia care unit. The patients were encouraged to void within 6 hours postoperatively and every 4-6 hours thereafter. After each voiding, the postvoid residual urine (PVR) was measured by an ultrasound bladder scan. POUR was defined as the inability to void or having a PVR≥100 mL for more than 2 days after surgery.

Results: The incidence of POUR was 27.1% (77/284). Older age (odds ratio, 1.062; 95% confidence interval, 1.029-1.095) and a long duration of surgery (odds ratio, 1.003; 95% confidence interval, 1.001-1.005) were significant risk factors. A formula for determining the probability of POUR was developed, and a probability of ≥0.26 was regarded as the cut-off value (sensitivity of 0.75 and specificity of 0.57; C-statics, 0.684).

Conclusion: POUR was a common morbidity after surgery for degenerative lumbar spinal stenosis. We recommend adopting a systematic postoperative voiding care protocol to prevent bladder overdistension and detrusor damage, especially for elderly patients and those who have undergone longer surgeries.

Keywords: Lumbar vertebra; Old age; Risk factor; Spinal stenosis; Surgery; Urinary retention.