Since it originates from a congenital malformation, extraperitoneal ureter hernias have also been found to be associated with other genitourinary abnormalities such as crossed renal ectopia
Crossed renal ectopia is a rare entity detected incidentally in 20 to 30% of cases  and results from the aberrant migration and crossing ofthe midline by the metanephric blastema and the ureteral bud , usually occurring during the fourth to eighth week of gestation .
Renal ectopia is generally classified either as a simple renal ectopia or as a crossed renal ectopia (CRE) .
Ultrasonography of the abdomen detected crossed renal ectopia
. A normal 46 XY karyotype was found.
However, unilateral crossed renal ectopia without fusion of the kidneys is an uncommon problem, occurring in one in 75,000 patients .
Crossed renal ectopia is a rare anatomic variant of the kidney.
Keywords: Crossed renal ectopia
, DMSA, Nephrectomy.
Other features of the syndrome include short stature, abnormality of phalyngeal bones, maxillary and mandibular abnormalities, obliterated maxillary sinuses, crossed renal ectopia
, and pelvic abnormalities.
Multicystic dysplasia and crossed renal ectopia
. AJR Am J Roentgenol 1987;149:407-10.
Anomalies associated with urachal remnants such as vesicoureteral reflux, meatal stenosis, hypospadias, umbilical and inguinal hernias, cryptorchidism, anal atresia, omphalocele and crossed renal ectopia
are rare, but should also be considered.
Treatment of renal calculus in inferior crossed renal ectopia
. Urology 1988; 32: 424-426.
Crossed renal ectopia
is a rare congenital anomaly in which both kidneys are situated on one side and fused together in 85%-90% of cases.