Distribution of post-void residual urine volume in randomly selected men

We describe the distribution of post-void residual urine volume and its relationship to other urological measurements in a random sample of men.

Post-void residual was measured by transabdominal ultrasonography after voiding and prostate volume was measured by transrectal ultrasonography in 477 randomly selected community dwelling white men as part of a baseline urological evaluation. Symptoms were characterized with the American Urological Association symptom index. Acute urinary retention cases with catheterization in the subsequent 3 to 4 years were identified through chart review.

The distribution of post-void residual was highly skewed with a median of 9.5 ml., and 25th and 75th percentiles equal to 2.5 and 35.4, respectively. There was a significant correlation of post-void residual with prostate volume (rs = 0.24, p <0.001). The odds of post-void residual greater than 50 ml. were 2.5 times greater for men with prostate volume greater than 30 ml. than those with smaller prostates. In regression analyses post-void residual did not appear to be associated with the American Urological Association symptom index, age or peak urinary flow rate. Men with enlarged prostate volume or post-void residual greater than 50 ml. at baseline were about 3 times as likely to have subsequent acute urinary retention with catheterization during 3 to 4 years of followup.

These results suggest little variation in the distribution of post-void residual urine volume across age groups or levels of urinary symptoms and peak urinary flow rate. However, a somewhat stronger relationship was found between residual urine and prostate volume.