To determine the predictive value of voiding efficiency on acute urinary retention after discharge from BPH surgery.

We performed a prospective observational cohort study of three surgeons’ practices from 2019 to present. All men included underwent trial of void on post-operative day one after transurethral resection of prostate or Holmium enucleation of prostate . Active filling void trials were performed on all patients and voiding efficiency (percent of bladder volume emptied) was calculated. Multivariable logistic regression was performed to determine predictors of developing acute urinary retention.

During the study period, 188 men met inclusion criteria. 110 (59%) men underwent Holmium enucleation of prostate , and 78 (41%) underwent transurethral resection of prostate. The median age of our cohort was 70 (IQR 65-75). The median prostate size was 100g (IQR 61-138g). Nineteen patients (10%) returned after discharge with acute urinary retention requiring catheterization. On post-operative day one, the median voiding efficiency was 75% (IQR 55%-94%). On multivariable analysis, patients with a voiding efficiency less than 50% were 3.8 times more likely (95% confidence interval 1.1-12.8) to develop subsequent retention compared to a voiding efficiency of greater than 75%. Increasing pre-operative prostate size was associated with lower risk of urinary retention after discharge (aOR 0.8, 95%CI 0.6-0.9).

Voiding efficiency after an active void trial helps stratify risk of urinary retention in patients undergoing benign prostate surgery. High-risk patients include those with voiding efficiencies less than 50% and smaller pre-operative prostate sizes (<80g).