ABSTRACT
Aetiology 1. Primary. The aetiology of PUJ obstruction is still controversial. Incomplete canalization during ureterogenesis along with abnormal development or orientation of the smooth muscle layers of the ureteral wall have been advanced as theories of obstruction intrinsic to the ureteric wall. Extrinsic obstruction is frequently attributed to a lower pole vessel passing anterior to the ureter of pelviureteric junction. This vessel is often described as aberrant, but is a variation of normal present in a minority of the population but present in around one-third of patients with PUJ obstruction.
