CAUSES

The diagnosis of ureteropelvic junction obstruction also known as UPJ obstruction implies there is blockage of urinary flow from the kidney down into the ureter.

Most cases tend to be congenital, i.e. the person is born with it, however, the majority of them do not manifest themselves as anything clinically significant until much later in life. Non-congenital causes include acquired conditions as a result of reflux from the bladder (vesicoureteral), narrowing as a result of either passing stones or trying to operate on stones, benign polyps, cancers within the urinary tract, or cancers/growth from outside the UPJ causing blockage within (‘extrinsic compression’).

Congenital blockage is usually related to three different conditions: 1) aperistaltic segment which implies that the normal muscle responsible for pushing the urine down is replaced by abnormal muscle bundles that are ineffective in pushing the urine from the renal pelvis down into the ureter; 2) high insertion point of the ureter into the renal pelvis causing ineffective drainage of urine from the dependent portion of the kidney; 3) crossing vessels whereby branch arteries from the main renal artery and vein cross behind the course of the UPJ and cause an intrinsic lesion within (see figures below).

DIAGNOSIS

Most adult patients present with flank pain, exacerbated by increased amounts of fluid intake, caffeine, or medication such as diuretics. A CT scan with contrast can provide detailed information both about the anatomy and function of the affected kidney. Modern imaging technology can assess for the presence of any crossing vessels. In addition, it can allow for the simultaneous diagnosis of any kidney stones. In children and babies, ideally ultrasound should be able to differentiate UPJ obstruction from other diagnoses and avoid unnecessary exposure to radiation. After initial CT or ultrasound exam, a nuclear renal scan with diuretic washout (Lasix) can help provide objective information about the degree of obstruction by assessing the split kidney function between the two kidneys and also assess the time it takes for the kidneys to washout the injected isotope. The T ½ is the amount of time it takes for the compound/isotope to be washed out of the kidney. T ½ of greater than 15 – 20 minutes usually implies significant enough obstruction that requires further intervention. In cases in which the imaging and/or functional studies are unclear, a cystoscopy and retrograde pyelogram (injection of contrast from the bladder up into the kidneys) can help confirm the diagnosis and identify the exact area of blockage so that definitive repair can be planned. The indications for treatment include moderate to severe symptoms, any damage to the kidney function, recurrent stones or infection, or high blood pressure as a result of the blockage.

TREATMENT

A temporary measure to bypass the blockage is to place a plastic tube (Double J Stent) with coils at the ends to prevent the tube from falling out of the kidney. This is not a practical way to address the blockage in most patients as it requires periodic changes of the stent every 4-6 months.

Minimally invasive endoscopic techniques have proven to be effective in select individuals depending on their coexisting conditions and overall health.  Some of the benefits of endoscopic repair include less post-operative time for recovery, avoiding any incisions, and being able to have this done on an outpatient basis.  An endoscopic repair is called an endopyelotomy and involves a full thickness incision of the ureter at the site of blockage.  Ureteroscopy (endoscopic procedure looking directly into the ureter) is usually required to identify the area of blockage and make the incision by use of laser energy or balloon dilation with cautery incision.  This incision is carried from the lumen of the ureter out to the surrounding fat around the ureter.  The opening subsequently heals over a special stent that is left in place for about 4-6 weeks.  Endoscopic repairs are usually effective in the long term in only 60-70% of patients.  In addition, almost half of patients that undergo endoscopic repair may continue to have some degree of chronic flank pain after this procedure.

The gold standard treatment of choice for UPJ obstruction has been a dismembered pyeloplasty whereby the affected area is removed and the renal pelvis is reconnected to healthy normal ureter.  Historically this type of reconstruction was done through an open incision usually through the flank.  Laparoscopic pyeloplasty was developed as a minimally invasive alternative to the open technique.  Laparoscopic pyeloplasty is associated with a shorter hospital stay, less pain medication, faster recovery and better cosmetic results while maintaining the over 90% success rate that is associated with a formal reconstruction.  Similar to what has been seen in the management of other urologic diseases pure laparoscopic repair is technically challenging and has been surpassed by the use of robotic assistance.  A robotic pyeloplasty provides increased degrees of movement, dexterity and precision which cannot be matched with pure laparoscopic techniques.  Our minimally invasive surgeons are fellowship trained and recognized experts in the use of robotic technology to perform complex reconstructions even after failed endopyelotomy and open repairs.  A robotic pyeloplasty is performed under general anesthesia, typically taking around 2-3 hours and requires a one-night stay in the hospital.  The operation involves using robotic instruments placed in the abdomen through 3-4 small incisions each less than half an inch in size.