Histopathology in Ureteropelvic Junction Obstruction With and Without Crossing Vessels.

OBJECTIVE: To determine if the histopathology of the ureteropelvic junction differs between those with and without crossing vessels who present with a ureteropelvic junction obstruction (UPJO).

MATERIALS AND METHODS: Our database was queried for patients undergoing pyeloplasty (Current procedural terminology 50400, 50405, and 50544) between June 1, 2002, and March 10, 2016. We excluded patients with other renal anatomic abnormalities and patients undergoing surgery for upper tract tumor. One genitourinary pathologist reviewed all slides for muscle hypertrophy, fibrosis, edema, and inflammation. Statistics were modeled in SAS 9.4 (SAS, Cary, NC) using logistic regression with maximum likelihood.

RESULTS: A total of 178 patients met the inclusion criteria, and pathology slides were available for 136 patients. Thirty-three patients had crossing vessels in association with a UPJO. The degrees of muscle hypertrophy (P = .89) and fibrosis (P = .17) were not predictive of etiology. The odds of a crossing vessel increased by 4.3 times (95% confidence interval 1.8-9.9) when edema was present (P = .009) and by 4.4 (95% confidence interval 1.4-13.7) times when inflammation was present (P = .0103).

CONCLUSION: In the largest pathology series to date, histopathology showed increased inflammation in the presence of a crossing vessel but a similar composition of muscle and fibrosis. These data suggest that UPJO with an associated lower-pole vessel may represent a chronic process, which would explain why patients with a crossing vessel present later in life.