To characterize afferent nipple valve obstruction in Kock diversions presenting with hydronephrosis and discuss appropriate work-up and management.

We retrospectively reviewed 7 cases of afferent nipple valve obstruction.

The median time from diversion creation to afferent nipple valve intervention was 17-years. Presentations included febrile-UTIs, worsening renal function and hydronephrosis. All patients underwent upper tract imaging confirming bilateral hydronephrosis or hydronephrosis of a solitary kidney followed by nephrostomy tube insertion to drain the obstructed kidney(s). On nephrostogram assessment afferent nipple valve obstruction was confirmed by a lack of contrast passing through the valve. In 4 of these patients the afferent valve could not be cannulated while in one patient endoscopic retrograde balloon dilation was performed but failed after 12-months. One patient had successful antegrade balloon dilation (four-years follow-up). In five patients and the one patient who failed retrograde balloon dilation open surgical repair of the afferent nipple valve was successful (median follow-up time 5-years).

It is essential to consider afferent nipple valve obstruction in a patient with a Kock diversion presenting with bilateral hydronephrosis/hydronephrosis of a solitary kidney, even after many years following the original diversion. Appropriate work-up consists of upper tract imaging, endoscopy and retrograde studies or nephrostomy insertion with nephrostogram. Management options include endoscopic retrograde or antegrade balloon dilation or valve incision. Failing that, surgical repair may be successful with long-term upper tract preservation.