巨输尿管症(Megaureter)是一种输尿管异常扩张之医学异常症状。先天性(Congenital disorder)巨输尿管症是一种罕见的病症，常见于男性中、不过男女性都可能会出现，并且通常与其它先天性的异常疾病有所关联。病因被认为是远程输尿管的蠕动停止(aperistalsis)，导致输尿管扩张所致。

功能性梗阻在输尿管的下端导致渐进性输尿管扩张及产生易感染的倾向。输尿管管口显出正常且导尿管通过容易。

明确的外科手术治疗涉及改造该受影响的输尿管下端，使得输尿管信道再植入膀胱可以做到防止回流的功能。

Megaureter is a medical anomaly whereby the ureter is abnormally dilated. Congenital megaureter is an uncommon condition which is more common in males, may be bilateral, and is often associated with other congenital anomalies. The cause is thought to be aperistalsis of the distal ureter, leading to dilatation.