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OBJECTIVES: To investigate if uroflowmetry (UFM) curve patterns could differentiate between detrusor underactivity (DU) and bladder outlet obstruction (BOO). METHODS: A hundred consecutive data sets of male patients who were evaluated using UFM and invasive urodynamics (pressure flow study) were retrospectively collected. DU and BOO were diagnosed according to the bladder contractility index and BOO index. The UFM curve with two or more notches was defined as sawtooth pattern, and the interrupted pattern was defined if several curves with interruptions reducing to zero were noted. We also compared other UFM parameters including maximum and average flow rates (Qmax and Qave), voiding time, time to Qmax, the slope to first peak flow, the number of notches on the curve (sawtooth pattern), the number of curves (interrupted pattern), and the maximum drop on the sawtooth pattern. RESULTS: Twenty-five and forty-nine patients were categorized in the BOO group and the DU group, respectively. The incidence of sawtooth pattern was significantly higher in the DU group (57%) than in the BOO group (32%), while the incidence of interrupted pattern was not different between the two groups (36% in the BOO group and 49% in the DU group). There were significant differences in age (area under the curve = 0.75), prostatic volume (0.67), the slope to first peak flow (0.58), the number of notches on the curve (0.61), and the maximum drop (0.76) between the two groups. CONCLUSIONS: The sawtooth UFM pattern is more common in patients with DU than in those with BOO. New parameters on UFM curve patterns could be helpful to evaluate DU and BOO without invasive urodynamics.
Wada et al. (Mon,) studied this question.