Presence of one or both kidneys in an abnormal position is called renal ectopia. Usually the ectopic kidneys are present at a lower position than usual and have not rotated to the normal extent. Pelvic kidneys result from failure of the kidneys to ascend from the pelvis into the abdomen. The pelvic kidneys usually lie close to each other and may fuse to form a discoid kidney called pancake kidney. The pelvic kidneys receive their blood supply from nearby vessels (internal or external iliac arteries) and are often supplied by multiple vessels. In crossed renal ectopia one kidney crosses to the contra-lateral side and its ureter crosses the median plane. In this condition the ectopic kidney and the normal kidney 8) Ureteric Duplication
may be fused to each other. In some cases the ureter may
be partially or completely duplicated.