PEARLS No. 246, April 2010, written by Brian R McAvoy

Clinical question
How effective are alpha-blockers in increasing the success rates of trial without a catheter (TWOC) after an episode of acute urinary retention in men?  

Bottom line
The limited available evidence suggests that, compared to placebo, alpha-blockers increase success rates of TWOC (NNT* 12). Two different alpha-blockers were tested (tamsulosin and alfuzosin). Alpha-blocker side effects were low and comparable to placebo. It is uncertain whether alpha-blockers reduce the risk of recurrent urinary retention and need for prostate surgery. The cost-effectiveness and recommended duration of alpha-blocker treatment after successful TWOC remains unknown. * NNT = number needed to treat to benefit 1 individual  

Caveat
There is a lack of internationally agreed outcome measures for what constitutes successful TWOC. This makes meta-analysis difficult. Treatment was given for 1 to 3 days (and in 1 study up to a maximum of 8 days) before the catheter was removed.  

Context
Acute urinary retention is a urological emergency in men and requires urgent catheterisation. Any intervention which increases the rates of successful TWOC following an acute urinary retention episode would be potentially beneficial. Alpha-blockers relax prostatic smooth muscle cells, thereby decreasing the resistance to urinary flow and by doing so improve urinary symptoms.  

Cochrane Systematic Review
Zeif H-J and Subramonian K. Alpha blockers prior to removal of a catheter for acute urinary retention in adult men. Cochrane Reviews 2009, Issue 4. Article No. CD006744. DOI: 10.1002/14651858.CD006744.pub2. This review contains 5 studies involving 696 participants.