Abnormal kidney location

There are three abnormalities of kidney location: simple renal ectopia or pelvic kidney, crossed renal ectopia, and horseshoe kidney. Simple renal ectopia is a kidney that is located on the correct side but in the pelvis, with the adrenal gland filling the renal fossa. With crossed renal ectopia, both kidneys are on the same side; one kidney is in the normal location and the other is located just below the first, with its ureter crossing the midline before inserting into the bladder. Horseshoe kidney indicates fusion of the inferior poles of the kidneys in the midline to form a horseshoe shape. Renal ectopia tends to be more challenging to detect prenatally than other renal abnormalities, particularly horseshoe kidney. Each type of ectopia is associated with increased risk for vesicoureteral reflux and ureteropelvic junction obstruction. Third-trimester evaluation is suggested, even in the absence of renal pelvis dilatation earlier in gestation. There is also a high prevalence of anomalies of other organ systems, and if any associated anomalies are identified, amniocentesis should be offered.