To understand what the PUJ is, requires some basic anatomical back ground information.
The kidney acts as a filter, filtering the blood with the excreted waste product being the urine. The urine collects within the collecting system of the kidney (calyces and renal pelvis).
The central renal pelvis drains into a tube (ureter) which drains all the way down to the bladder.
The PUJ is the point at which the renal pelvis joins the ureter.
What is a PUJ obstruction?
A PUJ obstruction is where there is an obstruction to normal urine flow from the renal pelvis into the ureter.
It may be classified as either:
Congenital/primary – essentially present since birth as a developmental abnormality. The cause of congenital PUJ obstruction is incompletely understood but may be as a result of abnormal insertion of the ureter into the renal pelvis, abnormal arrangement of ureteric musculature at the PUJ or a crossing vessel (usually artery) running in front of the PUJ causing an obstruction.
Acquired/secondary – this type of narrowing (stricture) may have resulted from previous surgery/instrumentation, kidney stones or trauma
What are the symptoms of a PUJ obstruction?
The classic symptoms of a PUJ obstruction are:
Flank pain – often worsened after consuming large volumes of fluids, especially alcohol
Recurrent urinary tract infections
Blood in urine (haematuria)
Rarely, the swollen/obstructed kidney can be felt in the flank region
How are PUJ obstructions diagnosed?
In some cases, a PUJ obstruction will be detected due to the presence of the above symptoms, resulting in further investigations which reveal the PUJ obstruction
Frequently, a PUJ obstruction will be detected incidentally on ultrasound or CT scans. A PUJ obstruction has a typical appearance on CT scan, however not all patients with this appearance will have obstruction to the urine flow. It is only patients which have a physical obstruction that require treatment.
What tests will be required to determine if a PUJ obstruction is significant?
A history and examination will determine if symptoms and signs exist suggesting an obstruction
Baseline tests required include:
Urine culture – to exclude a urine tract infection
Blood tests – to check baseline kidney function
CT Urogram/IVP – is a dedicated CT scan of the kidneys and ureter with intravenous contrast. It provides anatomical information to help determine if a true PUJ obstruction exists
Mag 3 scan – this specialised nuclear medicine scan is critical to determine if a true obstruction to kidney drainage exists. It will also provide a split function of the kidneys (i.e. what percentage of total kidney function each kidney is providing)
Cystoscopy/ Ureteroscopy – this is not required in all cases. Particularly in suspected acquired cases, a telescopic inspection of the PUJ will be required to determine the length of narrowing and to exclude any other pathology (e.g. stone or malignancy)
Do all PUJ obstructions require treatment?
All true PUJ obstructions require treatment, however as mentioned, not all patients with the appearance of a PUJ obstruction have significant obstruction.
Those that require treatment include:
Symptomatic obstruction (see above)
Impaired kidney function with obstruction
Reduced split function of affected kidney or falling split function on follow up scans (usually >10% difference between kidneys)
Recurrent urinary tract infections
Formers of kidney stones
Evidence of obstruction on Mag 3 scan – however, elderly patients or those with multiple medical problems may not require treatment
What are the treatment options for PUJ obstruction?
Surgery is the mainstay of treatment for a PUJ obstruction.
The gold standard is a pyeloplasty (for details see urological procedures explained)
A pyeloplasty is usually performed with key hole surgery (laparoscopic)
It involves cutting out the narrowed/obstructed PUJ segment and re-joining the ureter to the renal pelvis with sutures in such a way to allow unimpeded drainage
A ureteric stent will be left in the ureter for 6 weeks
The operation is successful in >90-95% cases
A Mag 3 scan will be performed 3 month after the Pyeloplasty to ensure unobstructed drainage
Endopyelotomy – is a minimally invasive surgical option for treating PUJ obstruction. It involves the passage of a fine telescope (ureteroscope) to the PUJ and the use of a laser to cut the stricture/narrowing along its length. A stent will be left in for 4- 6 weeks. It is less effective than a pyeloplasty in both the short and long term. Success rates range between 60-80%. For that reason it is not recommended as the first line option for a PUJ obstruction. It may be used in cases of a failed pyeloplasty with reasonable success.
Ureteric stent – long term. For some elderly patients with a significant PUJ obstruction that require treatment but are not fit enough to tolerate a pyeloplasty, a long term ureteric stent may be an appropriate option. This will need to be changed very 6-12 months