Alterations in Kidney Position and Form

The developmental process can result in kidneys that lie outside their normal position, usually just above the pelvic brim or within the pelvis. Because of the abnormal position, kinking of the ureters and obstruction of urine flow may occur. 

One of the most common alterations in kidney form is horseshoe kidney. This abnormality occurs in about I of every 500 to 1000 persons.5 In this disorder, the upper or lower poles of the two kidneys are fused, producing a horseshoe-shaped structure that is Continuous along the midline of the body anterior to the great vessels. Most horseshoe kidneys are fused at the lower pole. The condition does not cause problems unless there is an associated defect in the renal pelvis or other urinary structures that obstructs urine flow.