Presacral Anatomy in Women With a Horseshoe Kidney.

Objective: Horseshoe kidney (HSK) is the most common renal fusion defect that can alter vascular and upper urinary tract anatomy. Anatomic variations in the presacral space can make surgical dissection very challenging. The aim of this study was to characterize presacral anatomy in women with HSK.

Methods: Large academic centers' database was queried to identify imaging studies in adult women with HSK. Available multiplanar computed tomography and magnetic resonance imaging images were reviewed, and relevant vascular and upper urinary tract anatomy was measured and compared with published normal values. Study population was compared with the normal controls using Student t test, χ test, or Fisher exact test as appropriate.

Results: One hundred seventy-eight women were identified initially, and 20 confirmed to have HSK on imaging. The mean ± SD age was 54.5 ± 16.9 years, and body mass index was 27.3 ± 7.5 kg/m. Women with HSK had a narrower angle of aortic bifurcation (39.1 ± 18.7 degrees vs 55.6 ± 4.5 degrees, P = 0.014); the right ureter was closer to midline (22.9 ± 8.8 mm vs 32.3 ± 1.2 mm, P < 0.001) when compared with normal controls anatomy. In 40% of women with HSK, the bifurcation of the vena cava was below the level of L5 in contrast to the 8% in the normal population (P < 0.001). In 60% of women with HSK, the inferior pole of the kidney was at or below L5.

Conclusions: Ureteral, renal, and vascular anatomic alterations in women with HSK may make presacral surgical anatomy challenging by obscuring the anterior longitudinal ligament anchoring point. Preoperative imaging is warranted to determine the feasibility of female pelvic reconstructive surgery in HSK patients.