The termination of the normal ureter is in the posterior bladder wall at the superior lateral margin of the trigone. An ectopic ureter inserts more medially and caudally in the bladder, urethra, or genital tract. Usually, ectopic ureters drain the upper portion of a double system. Rarely, however, an unduplicated ureter draining an entire kidney terminates ectopically. The embryology and clinical and radiographic features of solitary ectopic ureters will be discussed below. Embryology (4) The ureters arise as medial buds from the caudal ends of the paired wolffian ducts. They rotate into a posterolateral direction as they grow cephalad into the metanephric blastoderm or future renal cortex (Fig. 1, A). By a series of divisions of their proximal ends, the renal pelves, major and minor calyces, and distal collecting tubules are formed. The distal ends of the ureters as well as their parent structures, the wolffian ducts, are incorporated into the formation of the bladder trigone. Thus, the ureters gain thei...