Rate of Post Obstructive Diuresis in Rapid Versus Gradual Bladder Decompression in Patients with Chronic Urinary Retention

Abstract

Background: Post-obstructive diuresis (POD) is a polyuric state in which copious amounts of salt and water are eliminated after the relief of a urinary tract obstruction. POD is a clinical diagnosis based on urine output exceeding 200 mL per hour for two or more consecutives hours or 3L in 24 hours after decompressing an obstructed bladder, bilateral ureteric obstruction or unilateral ureteric obstruction in a solitary kidney. Methodology: This was a prospective, randomized study in which patients with chronic urinary retention were randomized into two groups: A and B. Group A had rapid urinary decompression with 18Fr urethral catheter attached to a urine bag, while group B had gradual decompression using a urethral catheter attached to an intravenous fluid giving set which was then attached to urine bag. Post obstructive diuresis in each group were assessed at designated times. Data Analysis and Result Presentation: Data was analyzed using the Statistical Package for Social Sciences (IBM) SPSS version 21. Data was summarized by descriptive statistics. The two arms were compared for similarities in demographic variables. Continuous and categorical variables were compared using student t- test and Pearsons‘ Chi – square respectively. Significant p value was 0.05. Result: Sixty patients were recruited into the study and randomized into group A (rapid urinary decompression) and B (gradual urinary decompression) with 30 patients in each group. Thirteen patients (43.33%) had post obstructive diuresis in group A compared to 15 patients (50%) in group B. p value of 0.584. Diuresis resolved within 24 hours in 9 patients (30%) in group A and 11 patients (36.7%) in group B. p value of 0.999. The mean reduction in systolic blood pressure was 8.21 ± 2.63mmHg in group A and 7.63 ± 2.14mmHg in group B. p value of 0.583. The mean reduction diastolic blood pressure was 3.84 ± 1.31mmHg in group A and 3.41 ± 1.16mmHg in group B. P value of 0.624. No patient in both groups developed hypotension (BP of <90/60). Conclusion: There was no statistically significant different in post obstructive diuresis. However, over 46.7% of patients had diuresis in both groups without any one developing hypotension. This may be due to routine prophylactic fluid and electrolyte replacement using normal saline.