Afferent nipple valve malfunction caused by anchoring collar: an unexpected late complication of the Kock continent ileal reservoir. In the construction of a Kock continent ileal reservoir for urinary diversion, significantly high rates of late postoperative complications regarding nipple valves, the efferent limb in particular, have been reported. There are only a few reports on afferent nipple valve malfunction. A total of 42 patients who underwent a Kock pouch operation and were observed for more than 12 months (mean 38 months) was evaluated in terms of afferent nipple valve malfunction. Late afferent nipple valve complications were observed in 10 of the 42 patients (24%). These complications included erosion of the polyester fiber fabric used as a collar (5 patients), stenosis of the afferent limb (2) and obstruction of the afferent nipple by a mucous plug or fungus ball (3). The latter 2 complications were due to mechanical or dynamic obstruction of urine flow caused by a nonabsorbable collar. None of the 10 patients had problems with efferent nipple valve function. Our results suggest that the peristaltic direction of the intestine and the use of nonabsorbable material as a collar are primarily responsible for the late afferent nipple valve complications. Further modifications are needed to produce a stable nipple valve. Otherwise, simpler and more reliable alternative techniques of antireflux anastomosis should be considered. 