Medical Central Resource

Horseshoe kidney

Kristen Fults-Ganey

3/25/97

Presentation

3 year old female with an urinary tract infection.

Imaging Technique

Ultrasound MRI

Imaging Findings

  1. Renal ultrasound: Transverse image demonstrates isthmus connecting the inferior poles of the kidneys anterior to the abdominal aorta.
  2. MRI : T1 weighted axial images and T2 weighted coronal images demonstrate medial deviation of the lower poles of the kidneys which are fused by a parenchymal isthmus.

Diagnosis

Horseshoe kidney

Discussion

Horseshoe kidney is the most common renal fusion anomaly with an incidence of 1 in 400 people. It is two times more common in males compared to females.
Ten percent of the cases have fusion of the upper poles. In 90%, the lower poles are fused across the midline by a parenchymal or fibrous isthmus that lies anterior to the aorta and inferior vena cava at the L4/5 level. There is medial deviation of the fused lower poles which lie just caudal to the origin of the inferior mesenteric artery. The collecting systems and proximal ureters usually pass in front of the isthmus. The arterial supply varies and may arise from the lower aorta or common iliac artery. These aberrant arteries may cross and obstruct the proximal ureter or the UPJ.
Associated anomalies of the GU, GI, CV, or skeletal system occur in one third of patients. Other urinary tract anomalies which may coexist include upper tract duplication, MCK, and Wilm's tumor. There is often increased urinary stasis which predisposes to infection and stones. There is also an increased incidence of hydronephrosis, vesicoureteral reflux, and traumatic injury.

Submitted by: Kristen Fults-Ganey,Capt,USAF,MC,Wilford Hall Medical Center
Reviewed by: Cindy Taylor,LtCol,USAF,MC,Wilford Hall Medical Center

References