['The aim of this retrospective study was to evaluate in a historical series of patients whether morphological changes of the urinary tract imaged on intravenous urography (IVU) are associated with clinical or urodynamic data.', 'During a 1-year period, every man 45 years or older with lower urinary tract symptoms suggestive of benign prostatic hyperplasia was systematically evaluated with multi-channel computer-urodynamic investigation and IVU. Men with urinary retention, known bladder stones or diverticula, severely impaired renal function, or allergy to iodine contrast media were excluded. Structural alterations of the urinary tract were correlated with clinical and urodynamic data using logistic regression analysis.', 'Data on 203 consecutive patients were available for analysis. Multivariate analysis demonstrated that the "fish-hook" configuration of the distal ureter (also known as "hockey-stick", or "J-shaped" ureter) was the only sign significantly associated with benign prostatic obstruction (BPO) (odds-ratio 3.64; 95% confidence interval 1.69-7.83; P < 0.001). The sensitivity, specificity, positive and negative predictive values of the "fish-hook" ureter configuration sign to detect BPO was 53, 76, 61 and 70%, respectively. Bladder trabeculation, upper urinary tract dilatation, or bladder base elevation were not associated with BPO, detrusor overactivity, detrusor underactivity, bladder low-compliance or any clinical data.'] Does the fish-hook configuration of the distal ureter indicate bladder outlet obstruction due to benign prostatic hyperplasia?