Which feature best explains why patients with horseshoe kidneys have an increased incidence of hydronephrosis and stone formation?
- A Duplication of both ureters
- B Absence of a renal pelvis bilaterally
- C High insertion of the ureter with anterior displacement causing impaired drainage ✓
- D Retrocaval position of the left ureter
Correct answer: C. High insertion of the ureter with anterior displacement causing impaired drainage
Explanation
In horseshoe kidney the lower poles fuse across the midline, usually at L3, and ascent is arrested by the inferior mesenteric artery. Incomplete medial rotation leaves the pelvis facing anteriorly and the ureters insert high on the pelvis and pass over the isthmus. This abnormal anatomy causes impaired dependent drainage, stasis, hydronephrosis and stones. Duplex ureters and retrocaval ureter are separate anomalies unrelated to the horseshoe configuration.
Reference: Smith and Tanagho's General Urology, 19th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.