PELVIURETERIC JUNCTION OBSTRUCTION

Pelviureteric junction (PUJ) obstruction in adults
Definition
An obstruction of the proximal ureter at the junction with the renal pelvis resulting in a restriction of urine flow. Known as ureteropelvic junction obstruction  in North America (UPJO).

Epidemiology
Males > females (5:2 ratio). In unilateral cases, the left side is affected more often than the right. 10 - 15% are bilateral.

Aetiology
Congenital
- Intrinsic: smooth muscle defect results in an aperistaltic segment of ureter at the PUJ.
- Extrinsic: compression from lower renal pole vessel over which the PUJ runs. It is unlikely that these vessels are the primary cause of the obstruction. It is more probable that PUJO leads to a dilated PUJ and ballooning of the renal pelvis over the lower pole vessels, which may thus contribute to, but is not the primary cause of the obstruction.

Acquired
PUJ stricture secondary to ureteral manipulation (e.g. ureteroscopy); trauma from passage of calculi; fibroepithelial polyps; TCC of urothelium at PUJ; external compression of ureter by retroperitoneal fibrosis or malignancy.

Presentation
Flank pain precipitated by a diuresis (high fluid intake; especially precipitated by consumption of alcohol); flank mass; UTI; haematuria (after minor trauma). It may also be associated with vesicoureteric reflux (VUR).

Investigation
Renal ultrasound shows renal pelvis dilatation in the absence of a dilated ureter. IVU demonstrates delay of excretion of contrast and a dilated pelvicalyceal system. Arrange a CT to exclude a small, radiolucent stone, urothelial TCC, or retroperitoneal pathology which may be the cause of the obstruction at the PUJ. MAG3 renography with administration of frusemide to establish a maximum diuresis is the definitive diagnostic test for PUJO. Radioisotope accumulates in the renal pelvis, and following iv frusemide it continues to accumulate (a ‘rising  curve). Many urologists perform retrograde pyelography to establish the exact site of the obstruction, but they do this at the time of PUJ repair to avoid introducing infection into an obstructed renal pelvis.

Treatment
Surgery
Surgery is indicated for recurrent episodes of bothersome pain, renal impairment, where a stone has developed in the obstructed kidney, and where infection (pyonephrosis) has supervened. In the absence of symptoms, consider watchful waiting with serial MAG3 renograms. If renal function remains stable and the patient remains free of symptoms, there is no need to operate.

Endoscopic treatment of a PUJO is called an endopyelotomy (or pyelolysis). Various techniques have been described, but the essential principle is the same full-thickness incision through the obstructing proximal ureter, from within the lumen of the ureter down into the peripelvic and periureteral fat, using a sharp knife or Holmium:YAG laser. The incision is stented for 4 weeks to allow re-epithelialization of the PUJ. Relatively minimally invasive. Generally not used for PUJO >2cm in length.
The incision may be made percutaneously or by a retrograde approach via a rigid or flexible ureteroscope, or by using a specially designed endoplyelotomy balloon (the Acucise® technique).3
The presence of a combination of PUJO and a renal stone that is suitable for PCNL is an indication for combined PCNL and percutaneous endopyelotomy.
Success rates in terms of relieving obstruction: percutaneous endopyelotomy range from 60 - 100% (mean 70%); cautery wire balloon endopyelotomy 70%; ureteroscopic endopyelotomy 80%.

Pyeloplasty
- Open: has success rates of 95%, and may also be used after endopyelotomy failure or as a first line technique.
- Laparoscopic pyeloplasty has the advantage of accelerated patient recovery.
- Common techniques include dismembered pyeloplasty (also known as the Anderson - Hynes pyeloplasty: the narrowed area of PUJ is excised, the proximal ureter is spatulated and anastomosed to the renal pelvis), flap pyeloplasty (Culp), and Y-V-plasty (Foley).