[Uretero-pelvic junction obstruction due to crossing pole vessel: contra vascular hitch]

Hydronephrosis in infants and children is most commonly due to a congenital, intrinsic obstruction of the uretero-pelvic junction. The Gold standard of care is defined as a dismembered pyeloplasty, nowadays mostly performed in a minimally-invasive procedure, either through a laparoscopic (also robotic-assisted) or retroperitoneoscopic approach. Less common is an extrinsic obstruction of the ureter or the uretero-pelvic junction caused by an aberrant crossing pole vessel, a condition more likely to affect children beyond infancy. This entity most often becomes apparent when it causes intermittent abdominal or flank pain. For this entity, Hellström described a surgical procedure avoiding dismembered pyeloplasty by hitching the crossing vessel in a tunnel at the pyelon. This has been increasingly advocated as a valuable therapeutic alternative to dismembered pyeloplasty. The discussion on whether dismembered pyeloplasty or a vascular hitch procedure is preferable to resolve the obstruction is controversial and ongoing. There is evidence in the literature that in the case of a crossing pole vessel an intrinsic stenosis of the ureter may additionally be present in up to 57 % of cases. However, this finding can only be proven histologically. The intraoperative aspect of a crossing pole vessel and the uretero-pelvic junction does not serve to discriminate between intrinsic and extrinsic stenosis. Therefore, a vascular hitch procedure bears the risk that a remaining intrinsic obstruction will be disregarded, which, in turn, may lead to urodynamic obstruction and consecutive loss of differential renal function. In addition, there is a general risk of compromising the perfusion of the affected kidney while hitching an aberrant vessel providing significant blood supply. Dismembered pyeloplasty can avoid a false selection of patients. In addition, there is sufficient evidence showing that dismembered pyeloplasty is a procedure with a low complication rate ranging from 2 to 3 %, providing very good results in functional outcome in terms of improving drainage and preserving differential renal function. Therefore, we prefer dismembered pyeloplasty as the method of choice for both the treatment of intrinsic as well as extrinsic uretero-pelvic junction obstruction.