The rate of increase in urinary flow rate during micturition: a valuable urodynamic parameter for the diagnosis and differentiation of abnormalities of micturition in women.

The diagnostic significance of the maximum rate of increase in urinary flow during micturition, which is given by the tangent to the urinary flow curve at its point of maximum slope, was investigated at the University of Bern Women's Hospital. The micturition curves of 87 women were evaluated. Twenty four were in the control group, 36 had a variety of pathological conditions, and 27 had simple stress incontinence. For the measurement of urinary flow the bladder was filled until the subject felt the first need to micturate. The urinary stream was measured with an electronic balance (AMS flowmeter) and charted by a felt-pen recorder. In addition, continuous urethrocystotonometry was performed and urine was sampled for bacteriological examination. The results showed clearly that the maximum increase in urinary flow rate is of greater diagnostic value than the maximum and mean urinary flow or the micturition time. It is a simple, non-invasive method for differentiation between normal and pathological micturition curves. The discriminatory power of the test is age-independent. These investigations show that during the phase of active emptying of the bladder the rate of increase in urinary flow is the parameter which provides most diagnostic information.