A horseshoe kidney is a birth defect in which the lower poles of the two kidneys join across the midline, forming a U shape that sits low in the abdomen. Many people never know they have it, and it raises the risk of urine blockage, kidney stones and urinary infections.
Key symptoms
- Often no symptoms; found on imaging for another reason
- Flank or lower abdominal pain
- Fever and painful urination from a urinary infection
- Blood in the urine or passing kidney stones
What you find on exam
- Usually normal
- Flank or costovertebral angle tenderness with infection or stones
- Sometimes a midline lower abdominal mass
- Look for other congenital anomalies, for example in Turner syndrome
Tests
- Renal ultrasound showing a fused isthmus in front of the spine
- CT or MRI to define anatomy, blood supply and stones
- Urinalysis and urine culture
- Creatinine and eGFR
Treatment basics
- No treatment if there are no symptoms
- Antibiotics for urinary infections
- Stone treatment, often endoscopic or percutaneous because of the unusual anatomy
- Surgery to fix ureteropelvic junction obstruction when present
- Advice on protecting the kidney in contact sports
Red flags
- Fever with flank pain (possible infected obstruction)
- Blood in the urine after abdominal trauma
- Falling kidney function or reduced urine output
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.