Which renal anomaly involves fusion of the kidneys at the lower poles forming a horseshoe shape?

Which renal anomaly involves fusion of the kidneys at the lower poles forming a horseshoe shape?

• A. Horseshoe kidneys
• B. Absent kidneys
• C. Duplex kidneys
• D. Ectopic kidneys

Answer: (A)

Fusion of the kidneys at their inferior poles creates a horseshoe kidney. During development, the kidneys normally migrate upward from the pelvis to the upper abdomen. If the lower poles fuse, an isthmus of renal tissue forms across the midline, and this fused unit cannot ascend normally. The result is a U-shaped kidney that typically lies lower in the abdomen, often anterior to the aorta and inferior mesenteric artery. The ureters still drain into the bladder, but the unusual position and shared isthmus can be associated with atypical blood vessels and a higher risk of certain complications such as hydronephrosis or stones.

Fusion of the kidneys at their inferior poles creates a horseshoe kidney. During development, the kidneys normally migrate upward from the pelvis to the upper abdomen. If the lower poles fuse, an isthmus of renal tissue forms across the midline, and this fused unit cannot ascend normally. The result is a U-shaped kidney that typically lies lower in the abdomen, often anterior to the aorta and inferior mesenteric artery. The ureters still drain into the bladder, but the unusual position and shared isthmus can be associated with atypical blood vessels and a higher risk of certain complications such as hydronephrosis or stones.