Place of the free flow curve in the urodynamic investigation of children.

In a group of 210 children, predictions based on the form of the free flow rate curve, obtained without invasive instrumentation, have been compared with the results of a full urodynamic study. If the free flow curve is normal and there is no residual urine, then significant voiding abnormality, whether of functional or anatomical origin, is unlikely. If the free flow curve is abnormal or there is residual urine, then a full urodynamic investigation is indicated in order to determine the cause. A child with a normal free flow curve is more likely to show detrusor instability than a child with an abnormal free flow.