Design: Systematic review and meta-analysis of 8 randomised controlled trials
Population: Men with acute urinary retention due to benign prostatic enlargement
Primary outcome: Successful trial without catheter
Effect: Risk difference 24.5 percentage points (95% CI 18.4-30.7) vs placebo

This meta-analysis pooled eight randomised trials comparing an alpha-1 blocker with placebo in men catheterised for acute urinary retention due to benign prostatic enlargement. The outcome was successful voiding at trial without catheter.

Alpha-blockers increased the chance of success by 24.5 percentage points (95% CI 18.4 to 30.7). The authors report fewer recurrences and no significant increase in adverse events, though the abstract does not give figures for these.

The finding fits long-standing urology practice and puts a number on it. Postural hypotension is the main hazard in older, frail or volume-depleted patients, so start with the lowest dose and check lying and standing blood pressure.

Start an alpha-1 blocker such as tamsulosin when a man is catheterised for retention from benign prostatic enlargement.
Allow time on treatment before the trial without catheter, in line with local urology practice.
Check lying and standing blood pressure in older or frail patients after starting it.
Refer to urology if the trial fails or the retained volume was very large.

Why it matters

One inexpensive prescription meaningfully improves the chance that a man goes home without a catheter.

The statistics, in plain English

A risk difference of 24.5 percentage points means about one extra man in four voids successfully with the drug, so about four need treating for one extra success. The confidence interval (18.4 to 30.7) is well clear of zero.