Pyeloureteral Junction Obstruction vs. Intermittent Pyeloureteral Junction Obstruction
Left picture: Here, a classic intrinsic pyeloureteral junction obstruction is present which is caused by an interruption of the longitudinal muscles from the pelvis to the ureter, and a fibrosis. Right picture: This patient has an extrinsic stenosis of the pyeloureteral or subpelvic junction; in this case it is caused by an artery of the lower pole crossing the junction in front of it, leading to a furrow at the anterior proximal ureter with secondary damage to the ureteral wall. In the intermittent pyeloureteral junction obstruction, recurrent urinary tract infections are less in the forefront of the clinical presentation than intermittent abdominal colics.
Left picture: Detail of a grotesquely dilated renal pelvis. The examiner tries to introduce a probe from the distal end of the renal pelvis into the proximal ureter. Right picture: Excision of the pyeloureteral junction which is seen from the front. The lumen of the junction as well as of the proximal ureter are relatively wide and passable.