Objective: To evaluate predictors of reoperation after transurethral resection of the prostate (TURP) for benign prostatic hyperplasia (BPH) in a diverse patient population. Materials and methods: A retrospective chart review was performed on men who underwent TURP between 2013 and 2016 at our institution with follow-up data post-operatively. Variables collected included patient demographics and clinical characteristics. Primary outcomes included whether the patient underwent repeat TURP and months elapsed since initial TURP. Results: A total of 304 men underwent TURP during the study period. Thirty men (10%) underwent repeat TURP at a mean interval of 26 months. Reoperation after TURP was not associated with race, body mass index (BMI), 5-alpha-reductase inhibitor (5-ARI) use, or pre-operative prostate volume. An elevated pre-operative haemoglobin A1c (HbA1c) was associated with both reoperation (odds ratio (OR) = 1.32, 95% confidence interval (CI): 1.03–1.69), 30 day readmission (OR = 1.96, 95% CI: 1.17–3.28) and 30-day hematuria (OR: 2.37, 95% CI: 1.29–4.38). Pre-operative prostate specific antigen (PSA) levels > 4 and hydronephrosis on imaging were also associated with a higher risk of reoperation. Conclusions: Reoperation after TURP occurred in 10% of our study cohort at a median of 26 months after surgery. Elevated HbA1c prior to surgery was associated with reoperation, 30-day readmission and 30-day hematuria. Higher risk of post-operative complications in patients with poorly controlled diabetes should be communicated at the time of decision for surgery. Future studies should evaluate whether optimising diabetes control prior to TURP reduces risk of reoperation or whether this risk is non-modifiable due to permanent changes in the lower urinary tract due to chronic hyperglycaemia. Level of evidence: III

men 45 to 80 years old with a prostate between 30cc and 80cc. WATER II (NCT03123250) is a prospective, multicenter, single-arm international clinical trial of Aquablation in men with a prostate between 80cc and 150cc. We compare 36-month outcomes amongst 116 WATER and 101 WATER II study subjects undergoing Aquablation. Students' t-test or Wilcoxon tests were used for continuous variables and Fisher's test for binary variables.RESULTS: International Prostate Symptom Score (IPSS) scores improved from 22.9 and 23.2 at baseline in WATER and WATER II, respectively, to 8.0 and 6.4 at 36 months, with 36-month reductions of 14.4 and 16.7 points, respectively (p[.07 for difference in change scores). At baseline, urinary flow rate (Qmax) was 9.4 and 8.7 cc/sec in WATER and WATER II, improving to 20.6 and 19.0 cc/sec, respectively (p[.70 for difference in change scores) at 36 months. Improvements in both IPSS and Qmax were immediate and sustained throughout follow-up. Change in IPSS, Qmax, and post-void residual (PVR) can be found in Figure 1.CONCLUSIONS: Aquablation clinically normalizes outcomes between patients with a 30cc to 80cc prostate and patients with an 80cc to 150cc prostate treated for LUTS/BPH. It is effective in patients with large prostate glands (>80cc) with acceptable complications out to three years. Source of Funding:The WATER and WATER II clinical trials are funded by PROCEPT BioRobotics. This abstract is submitted on behalf of all WATER and WATER II investigators