What is a horseshoe kidney?
A horseshoe kidney is the most common type of congenital renal fusion anomaly, occurring in 1 in 500 people, in which the lower poles of the kidneys are attached to each other across the midline, leading to a “horseshoe” configuration. The region of connection, called the isthmus, is composed of fibrous tissue or functioning renal parenchyma and is located just inferior to the inferior mesenteric artery.
Patients with a horseshoe kidney are generally asymptomatic but have an increased risk of a malformed ureteropelvic junction with resultant obstruction, vesicoureteral reflux (VUR), nephrolithiasis, renal traumatic injury to the isthmus in blunt abdominal trauma, urinary tract infections, and renal neoplasms including Wilms tumor and urothelial carcinoma.
