Urinary flow in healthy schoolchildren.

The urinary free flow in 180 healthy schoolchildren aged 7-16 years was examined with a new kind of uroflowmeter. The examinations were performed at ordinary school toilets and each child presented at least two registrations. Besides the shape of the flow curve, the urinary flow was evaluated by the parameters voided volume, maximum flow rate, average flow rate, flow at 1 second and at 0.5 seconds, time to maximum flow, and voiding time. All parameters were related to sex, age, and body parameters. Two recorded micturitions are considered a minimum to obtain a reliable assessment of the urinary flow curve of a child and the shape of the curve is the most important factor to analyse. The normal flow curve is "bell-shaped" regardless of sex, age, and voided volume, and the urine is emptied in one portion. At the first micturition, more curves are irregular and flow rates are significantly lower than at the second one. Voided volume, maximum flow rate, average flow rate, time to maximum flow, and voiding time increase weakly but significantly with age and body parameters. Maximum flow rate, average flow rate, and the flow at 1 second are significantly higher for girls and are correlated to each other. All examined flow parameters except the flow at 0.5 seconds are significantly correlated to voided volume. The results differ from previous studies of children by larger voided volumes, shorter voiding time and time to maximum flow and by higher values for maximum flow rate, average flow rate, and flow at 1 second.