World J Urol (2011) 29:199–204 201 Fig. 1 Intravenous urography imaging the urinary tract 15 min after contrast media infusion showing bilateral ‘‘ﬁsh-hook’’ ureters (?) and hydronephrosis in an 64-year old men with BPH–LUTS (a) as well as a unilateral ‘‘ﬁsh-hook’’ ureter (?) and elevated bladder base (*) in an 70-year old man with BPH–LUTS (b) voiding (DAMPF [12]), (f) presence/absence of BPO (Scha¨fer nomogram). Signiﬁcant predictors detected were further evaluated after adjusting for possible confounding patient characteristics, namely age, prostate volume, PVR and bladder capacity at UDI. Results Data on 203 men were available for analysis. General patient characteristics and the number of patients with the speciﬁc IVU or urodynamic ﬁndings are summarized in Table 1. Univariable binary logistic regression analysis revealed • presence of stones was signiﬁcantly associated with low bladder compliance (OR 3.84, 95% CI: 1.29–11.43; P = 0.016), • elevation of the bladder base was signiﬁcantly associated with BPO (OR 2.01, 95% CI: 1.14–3.54; P = 0.016), • ‘‘ﬁsh-hooked’’ conﬁguration of the distal ureter(s) was signiﬁcantly associated with BPO (OR 3.59, 95% CI: 1.96–6.57; P \ 0.001). When potential confounding variables (age, prostate volume, PVR, and bladder capacity) were taken into account in the respective multivariate regression models to test the aforementioned signiﬁcant associations, only the association between the ‘‘ﬁsh-hook’’ ureter(s) and BPO remained signiﬁcant (Table 2; models for stones and bladder base elevation with insigniﬁcant ﬁndings not shown). Based on the multivariate regression model, BPO was the only independent predictor of ‘‘ﬁsh-hook’’ ureters. The sensitivity, speciﬁcity, positive and negative pre- dictive values of ‘‘ﬁsh-hook’’ ureter(s) to diagnose BPO was 53, 76, 61 and 70%, respectively, resulting in an overall test accuracy of 67%. The likelihood ratio of a positive test result was 2.22 (95% CI 1.51–3.24; Table 3). Table 4 demonstrates the general characteristics of patients with or without the ‘‘ﬁsh-hook’’ sign of the distal ureter(s) indicating a signiﬁcantly greater prostate volume and higher serum PSA level in the former subgroup. Discussion We investigated in a historical group of unselected patients with BPH–LUTS the relationship between morphological and functional signs of the urinary tract, determined by IVU and UDI, respectively. The ‘‘ﬁsh-hook’’ shape of the distal ureter(s) was found to be signiﬁcantly associated with BPO. To the best of our knowledge, we present for the ﬁrst time urodynamic evidence for this association. The ‘‘ﬁsh-hook’’ ureter has been described in many urological textbooks [13–15] and was regarded as a sign of BPE [16, 17]. According to the department policy, every man with BPH–LUTS was investigated with the identical assessment protocol in 1994. Only patients with other possible causes of LUTS and those unsuitable for IVU or UDI were excluded. Men with known bladder stones, diverticula, or urinary retention were deprived of UDI because they were considered obstructed [18] and were submitted directly to prostate surgery. Consequently, our study group consisted of 203 consecutive patients who were able to void and considered to have uncomplicated BPH–LUTS. Inclusion of more patients might have resulted in selection bias, because UDI was incomplete during 1991–1993 and IVU for the routine assessment of patients with BPH–LUTS was rarely performed in 1995 and ﬁnally abandoned in our department in 1996. A similar study today using IVU or CT imaging does not seem to be ethically justiﬁed due to the 123