Introduction: Horseshoe Shaped (HSK) Kidneys are often asymptomatic and are frequently diagnosed incidentally. The prevalence varies from approximately 1 in 400 to 600 with preponderance in males (male: female ratio of 2:1). This abnormality can affect the drainage of the kidney leading to Pelviureteric Junction Obstruction (PUJO), renal calculi, urinary tract infections and some renal cancers. The superficial location also makes it more vulnerable to injury during trauma or surgical procedures. Aim: To assess the prevalence of HSK and report their morphological features as evidenced following examination with a 64-slice Computed Tomography of the Kidney and Urinary Bladder (CT KUB). Materials and Methods: A retrospective study was conducted in the Department of Radiology, Sri Muthukumaran Medical College and Hospital & Research Institute, Chennai from January 2017 to December 2018. The study included 861 patients who underwent 64 slice CT KUB during that period and review of both plain and contrast enhanced CT KUB examinations were done. For deciding the fusion site, the isthmus, the authors measured a maximum diameter of the outline of the HSK on the axial image and decided the center of the kidneys. The HSK was classified based on fusion site and type of isthmic tissue connecting two kidneys. Results: HSK was found in 4 (3 male and 1 female) out of 861 patients examined. Thus, the prevalence of HSK in the study population was 1 in 215 (0.46%). Two patients with a thick isthmus and anteriorly facing, pelvises had PUJO and urolithiasis. Variant vascular anatomy was found in all four patients. No crossed fused ectopia was found in this study. Conclusion: This study showed that HSK is the most common congenital fusion anomaly and is more common in males. It also demonstrated that patients with a thick isthmus and associated anteriorly facing renal pelvis were more prone to develop PUJO and renal calculi.

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