Venous supply of horseshoe kidneys and normal kidneys: an angio-multislice computed tomography-based study

Background: Horseshoe kidney (HSK) is a common developmental anomaly which can be associated with many atypical anatomical variants of blood supply. The aim of this study was to identify the anatomical variants of renal veins supplying HSK, with particular emphasis on their relationship with the arterial system. Materials and methods: The analysis included 94 patients with HSK and 248 persons with normal kidneys (NK). Based on computed tomography-angiography, the number of renal arteries and veins was determined, along with the levels the arteries branched off the aorta and the veins communicated to their parental vessels. Results: Four hundred and twenty-three renal arteries (4.5 per person) and 364 renal veins (3.78 per persons) were found in HSK group (p = 0.004), as compared with 598 arteries (2.41 per person) and 567 veins (2.29 per person) in the NK group (p = 0.025). Mean number of renal veins in women with HSK was higher than in men (4.11 vs. 3.72 per patient, p = 0.03). In the HSK group, the number of renal arteries correlated significantly with the number of renal veins only among men (ks = 0.35, p = 0.009). In patients with NK, significant correlations between the number of renal arteries and renal veins were found both in the whole group and among men and women. Conclusions: Horseshoe kidneys are drained by a higher number of renal veins than NK, especially in women; this also refers to accessory renal veins. The number of renal veins for HSK is less dependent on the number of corresponding arteries than these for NK. (Folia Morphol 2023; 82, 2: 368-374)