To search for independent predictors for distinguishing bladder outlet obstruction (BOO) and detrusor underactivity (DU) in female patients with voiding difficulty.

A retrospective patient file review was performed of 918 female patients with lower urinary tract symptoms. After exclusion criteria, 148 patients with voiding difficulty were eligible for the study. Patients were classified as having BOO and DU based on urodynamic BOO and DU definitions. The symptoms, patient characteristics, the patterns of free urine flow, and detrusor voiding pressure curves were compared between 2 groups.

Of 148 patients with a median age of 53 (18-86), 42 (28,4%), 37 (25%), 69 (46,6%) patients had a urodynamic diagnosis of BOO, DU, and unclassified P/F study respectively. Multivariate logistic regression analysis results showed that the symptom of weak urine stream [P = .015 OR = 7.07 CI(1,47-34,0)], the negative provocative stress test [P = .038 OR = 7.32 CI(1,12-47,83)], the continuous detrusor voiding pressure and the prolonged/tailed shaped free urine flow curve patterns [P < .001 OR = 2,99 CI(1,66-5,38)] were the independent predictors of BOO. Sensitivity and specifity values for prolonged/tailed to predict BOO were 82.5 and 60% respectively.

The continuous detrusor voiding pressure and the prolonged/tailed shaped free urine flow curve patterns were found to be useful independent predictors for distinguishing BOO from DU in female patients with voiding difficulty. In addition, the symptom of weak urine stream, and the negative provocative stress test may be of beneficial use.