Donor: Royal Victoria Hospital
Size (H x W x D cm): 22 x 22 x 6
The kidneys are fused at their lower poles in the midline; two ureters insert into the bladder normally (back view, A).
A. Click on image to enlarge.
History: Forty-four year-old man. History unknown.
Comment: Normally the kidneys develop in the pelvis and ascend between the iliac arteries to the lumbar region. Occasionally, one of them fails to make this ascent and remains in the pelvis near the common iliac artery (ectopic kidney; see specimen 27). In other individuals, both kidneys approximate each other and fuse together as they attempt to pass upward through the iliac bifurcation. Further ascent is prevented by the inferior mesenteric artery and the fused portion remains in the lower abdomen at the level of the lumbar vertebrae, with two lobes on either side above forming the “horns” of the “shoe”.
Ectopic kidney occurs in about 1 in 1000 live births. It is usually asymptomatic and unassociated with complications. Horseshoe kidney is more common (1 in 500 births) and is more likely to be associated with symptoms (e.g., abdominal pain) and complications such as stones (nephrolithiasis) or infection (pyelonephritis).