ABSTRACT
Fluctuations in detrusor contractility, straining, or intermittent sphincter activity during voiding may result in com-
plex flow patterns ( Figs. 29.3 and 29.5 ). Rapid changes in flow rate may be due to sphincter/pelvic floor contractions, mechanical compression of the urethral lumen or interference at the meatus, or to changes in the driving energy as with straining. Rapid changes may also be due to artifacts caused by interference between the stream and the collecting device, movement of the stream across the surface of the funnel or patient movements. If fast variations of urinary flow have been observed, patients should be asked if this voiding pattern reflects normal voiding at home, they have strained, or emptied their bladder next to the collecting device. A visual control with regard to urine remnants next to the flowmeter might be useful in cases of suspected voiding next to the uroflowmeter.
