The dilemma of the crossing vessel at the ureteropelvic junction: precise anatomic study.

To maximize the success rate of endopyelotomy with minimal risk of complications, some debate still persists on the technique of incising the ureteropelvic junction (UPJ), patient selection, and prognostic factors. Also, some controversy exists concerning the vascular complications associated with the procedure. In order to give anatomic background to better clarifying the issue of a crossing vessel at the UPJ, we analyzed its vascular anatomic relations in 546 kidneys divided as following: 82 three-dimensional polyester resin corrosion endocasts of the collecting system together with the intrarenal arteries, 52 endocasts of the collecting system together with the intrarenal veins, 146 endocasts of the collecting system together with the intrarenal arteries and veins simultaneously, and 266 in situ dissected kidneys. In 65% of the endocasts, we found a prominent artery, vein, or both in close relation to the ventral surface of the UPJ. Among these cases, in 45%, the relation was with the inferior segmental artery. With respect to the presence of multiple renal arteries, in only 6.8% of the cases did an inferior polar artery cross anteriorly to the UPJ. In 6.2% of the endocasts, there was a direct relation between a large vessel and the dorsal surface of the UPJ. In additional 20.5% of the cases, there was a vessel crossing lower than 1.5 cm above the posterior surface of the UPJ. Considering these anatomic findings, it is conceivable that many of the vessels seen during angiography in a close relation to the UPJ and described as anomalous and etiologic in obstruction would be normal segmental arteries that do not cause UPJ obstruction. Also, on the basis of the anatomic findings, we advise that in endopyelotomy, the incision along the stenotic UPJ wall be created only at its lateral aspect.