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Introduction: Post-operative urinary retention (POUR) following primary total joint arthroplasty (TJA) has a reported prevalence up to 35%. Risk factors for developing POUR have traditionally included surrogate markers such as the presence or absence of urologic disease. However, dynamic measurement of the renal system with post-void residual volumes (PVR) has not been investigated as a tool for assessing POUR risk.

Methods: All male TJA patients underwent an pre-operative screen for POUR, including PVR measurements, patient-derived subjective urinary retention scores, and assessment of urologic disease. This was combined with a post-operative monitoring and catheterization protocol developed in partnership with a Urologist. Patient records were retrospectively reviewed and assessed whether pre-operative PVR cutoffs or urinary retention scores were associated with developing POUR. Proportions were evaluated with the chi square test, while continuous variables were evaluated by logistic regression analysis. Receiver-operator characteristic (ROC) curves were utilized to determine the efficacy of using urodynamic variables as a predictor of developing POUR.

Results: Two hundred and fifty-two (252) male patients were reviewed who had a mean age of 64.9 years and mean BMI 30.8 kg/m2. The overall rate of POUR was 5.2%; the rate of protocol-driven catheterization was higher (19.8%). Patient urinary retentions scores were not associated with the risk of POUR. Elevated pre-operative PVR (>10 cc) alone and in combination with a history of urologic disease was significantly associated with POUR (p < 0.001 and p = 0.001, respectively). However, both had low positive-predictive values (10.5 and 18.2%, respectively), despite high negative predictive values (99.2 and 97.9%, respectively). Utilization of PVR resulted in moderate sensitivity (91.6%) and low specificity (72.1%) with an AUC of 0.694.

Discussion: Urodynamic measurements and patient urinary retention scores, as part of institutional pre-operative screening, have limited value in determining risk of POUR. False-positive rates of up to ~90% were observed with correspondingly low specificity. The authors call into question the utility of obtaining these measurements pre-operatively, particularly as they have no modifiable impact on institutional post-operative catheterization protocol.