Q: What are normal residual urine volumes?
A: What constitutes abnormal residual bladder urinary volumes is debated; however, residual volumes greater than 150 milliliters on two occasions are suggestive of urinary retention (which may result in “overflow” incontinence) and should prompt further evaluation for voiding dysfunction.
Teaching topics from the New England Journal of Medicine - Vol. 358, No. 10, March 6, 2008