A Quantitative Histological Evaluation of the Dilated Ureter of Childhood. II: Ectopia, Posterior Urethral Valves and the Prune Belly Syndrome

A quantitative histological study was performed on specimens of 33 ureters obtained from 14 male and 19 female patients 5 days to 14 years old (mean age 1.2 years). A high resolution color image video analysis system was used to quantify and compare collagen and smooth muscle components of the muscularis layers to normal control ureters from patients of similar ages. In comparing ureters with ectopia (7), ureters with ectopic ureteroceles (20) and control ureters (4) there was not a statistically different collagen-to-smooth muscle ratio among the groups. In the patients with posterior urethral valves the amount of collagen and smooth muscle was not statistically different from controls (p >0.01), although the collagen-to-smooth muscle ratio was increased. The 4 patients with the prune belly syndrome had a collagen-to-smooth muscle ratio that was markedly elevated (1.21 versus 0.39) compared with controls. When this group was analyzed as 2 separate groups (obstructed versus refluxing ureters) the difference was more apparent (p <0.004). Ureters with ectopia or ectopic ureteroceles and ureters associated with posterior urethral valves had similar quantitative amounts of smooth muscle (60%, 56% and 52%, respectively). In patients with the prune belly syndrome obstructed ureters had 65% muscle and refluxing ureters had 38% muscle on evaluation. The percentage of collagen was 33% in ureters with ectopia, 37% in those with ureteroceles and 48% in those associated with posterior urethral valves compared with 23% in controls. In the group with the prune belly syndrome there was 30% collagen in obstructed ureters and 62% collagen in refluxing ureters. Our findings demonstrate that while these dilated ureters had different etiologies the overall quantitative composition of collagen-to-smooth muscle ratios was similar except in refluxing ureters associated with the prune belly syndrome. Our study provides further insight into the pathological nature of such ureters and considerations for surgical repair.