The most frequent anomaly of the urogenital tract is a simple renal ectopia with one organ lying in the pelvis. Crossed renal ectopia is a less common condition in which the ectopic kidney is located on the opposite side of the midline from the ureteral insertion in the urinary bladder. The cause of both types of renal ectopia is the arrest or failure of the kidney ascent from the pelvic to the lumbar position. Whereas an accelerated ascent leads to a subdiaphragmal or intrathoracic ectopic position, an ectopic ureter can be defined as one that does not drain into the trigonum vesicae. The ectopic orificium can be located situated in the bladder neck and urethra as well as somewhere in the genital area.Exstrophy of the urinary bladder is not a complete ectopia. Because the abdominal wall and the anterior part of the bladder wall are lacking, the bladder mucosa grows directly into the skin. The complex exstrophy of the bladder and intestine corresponds to a cloacal exstrophy, in which the bladder is split in two halves on either side of the gut portion. Testicular ectopia refers to the location of the testis in a position outside of its normal course of descent.Prostatic ectopia does not refer to the wrong location of the entire organ, but to a scattered group of prostate glands, which are mostly found in the submucosal part of the urinary bladder or proximal urethra. Other described locations are the intestinal wall, anus, pericolic fat tissue, spleen, seminal vesicle, testis, and cervix uteri.The associated ectopic penis, scrotum, and penoscrotal transposition are the least common and probably the absolutely most unknown malformations of the male genitalia. The ectopic penis and scrotum are located in the perineum, whereas in the transposition the penis lies above the scrotum.
