Gross and Histologic Anatomy of the Pelvic Ureter: Clinical Applications to Pelvic Surgery.

OBJECTIVE: To further evaluate relationships of the pelvic ureter to clinically relevant structures and to characterize the anatomy, histology, and nerve density of the distal ureter. METHODS: In this observational cadaveric study, 35 female cadavers were examined, 30 by gross dissections and five microscopically. Ureter length and segments of pelvic ureter were measured. Closest distances between the ureter and clinically relevant points were recorded. The distal pelvic ureter and surrounding parametrium were evaluated microscopically. Nerve density was analyzed using automated quantification of peripheral nerve immunostaining. Average measurements of nerve density in the anterior and posterior quadrants surrounding the ureter were statistically compared using a two-tailed t test. Descriptive statistics were used for analyses with distances reported as mean±SD (range). RESULTS: Gross dissections revealed ureter length of 26.3±1.4 (range 24-29) cm (right), 27.6±1.6 (25-30.5) cm (left). Lengths of ureter from pelvic brim to uterine artery crossover were 8.2±1.9 (4.4-11.5) cm (right), 8.5±1.5 (4.5-11.5) cm (left) and from crossover to bladder wall 3.3±0.7 (2.4-5.8) cm (right), 3.2±0.4 (2.6-4.1) cm (left). Intramural ureter length was 1.5±0.3 (1-2.2) cm (right) and 1.7±1.2 (0.8-2.5) cm (left). Distances from the ureter to uterine isthmus: median 1.7 (range 1-3.0) cm (right) and 1.7 (1.0-2.9) cm (left); lateral anterior vaginal fornix 1.5 (1.0-3.1) cm (right) and 1.7 (0.8-3.2) cm (left); lateral vaginal apex 1.3 (1.0-2.6) cm (right) and 1.2 (1.1-2.2) cm (left) were recorded. Microscopy demonstrated denser fibrovascularity posteromedial to the ureter. Peripheral nerve immunostaining revealed greater nerve density posterior to the distal ureter. CONCLUSION: Proximity of the ureter to the uterine isthmus and lateral anterior vagina mandates careful surgical technique and identification. The intricacy of tissue surrounding the distal ureter within the parametrium and the increased nerve density along the posterior distal ureter emphasizes the importance of avoiding extensive ureterolysis in this region.