Horseshoe kidney

Case contribution: Dr Radhiana Hassan


  • A 64 years old man
  • Underlying HPT and CVA, gastric adenocarcinoma-lesser curvature
  • CT scan abdomen as part of investigation for tumour.
  • Patient has no urinary symptoms
Contrast-enhanced CT scan in axial planes

CT scan findings:

  • Both kidneys are malrotated (red arrows)
  • The lower poles are fused together at midline (yellow arrows).
  • No renal calculus or hydronephrosis.
  • Urinary bladder is well distended and normal.
  • Prostate is not enlarged, measures about 3.8cm x 3.8cm x 3.2cm (AP x W x CC).

Diagnosis: Horseshoe kidney


  • Horseshoe kidneys are the most common type of renal fusion anomaly. It is usually asymptomatic and diagnosed incidentally.
  • It is more common in males.
  • It is formed by fusion across the midline of two distinct kidneys by functioning renal parenchyma or fibrous tissue.
  • The kidneys are low lying and susceptible to trauma.
  • There is also has higher risk for renal calculi and transitional cell carcinoma. Other complications include hydronephrosis, infection, pyeloureteritis cystica and renovascular hypertension.
  • Horseshoe kidneys are frequently associated with genitourinary and non-genitourinary malformations.
  • CT and MRI demonstrate renal tissue of normal imaging appearance but abnormal configuration. Enhancement and excretory phases are normal.
  • Common features on imaging include:
    • Midline symmetrical fusion of lower poles in 90% of cases or lateral asymmetric fusion in 10% of cases
    • Position of fused kidneys are lower than normal with incomplete medial rotation
    • Renal pelvis and ureters are positioned more anteriorly and ventrally cross the isthmus
    • Isthmus that may be positioned below the inferior mesenteric artery
    • Variant arterial supply that can originate from the abdominal aorta or common iliac arteries
    • Lower poles of kidneys that extend ventromedially and may be poorly defined.


Author: radhianahassan