先天性输尿管口异位是在胎儿时期形成的输尿管发育反常。在胚胎第四周时,输尿管胚芽从泄殖腔腹部发生,中肾管亦开口予其中,此后两侧输尿管口移向上方,而在膀胱三角两侧开口,这是胚胎发育的正常情况。如果发育反常,而形成输尿管口的异位。因为有中肾管的根源,男性输尿管可在后尿道、射精管或精囊内开口,它们仍受到外括约肌的控制,故无尿 Congenital ureteral orifice ectopic ureter dysplasia is formed during the fetal period. In the fourth week of the embryo, the ureter germ occurs from the cloacal abdomen, and the middle kidney tube is also open to it. After that, the ureter mouth moves upwards and opens on both sides of the trigone. This is a normal condition for embryo development. If abnormal development, and the formation of ureteral orifice ectopic. Because of the root of the kidney, male ureters in the posterior urethra, ejaculatory duct or seminal vesicle opening, they are still outside the control of the sphincter, it is anuria