Surgery versus non-surgical management for unilateral ureteric-pelvic junction obstruction in newborns and infants less than two years of age

Review question

Do children with unilateral ureteric-pelvic junction obstruction do better with or without surgery?


Some newborn and infants less than two years of age are shown using ultrasound to have an enlargement of the pelvis of the kidney. This is the anatomical structure where the urine collects before it is transported down the ureter to the bladder. Enlargement of the pelvis of the kidney is a concern due to possible blockage of urine flow, not unlike how a river widens in front of a dam.

Longer-term blockage of the urine flow for months and years may damage the kidney and lead to other problems such as urinary tract infections or kidney stones. Surgery can remove a blockage if it occurs, but it also has downsides including risks of complications. It is unclear whether these operations are necessary.


We searched for studies up to 13 June 2016 and found two trials that compared groups of newborns and infants less than two years of age, including a total of 107 children who had surgery or no surgery and were followed for up to five years. Based on very low-quality evidence, we found that short-term kidney function (after six and 12 months) was similar in the two groups. Very low-quality evidence also showed that after surgery, the pelvis of the kidney was smaller and urine seemed to flow better from the kidney down the ureter. However, due to the methods and size and of the studies, we are very uncertain about these results. There was insufficient evidence to determine whether one group of participants did better longer term, had fewer complications, or had better quality of life.

Authors' conclusions: 

We found limited evidence assessing the benefits and harms of surgical compared to non-surgical treatment options for newborns and infants less than two years of age with unilateral UPJO. The majority of participants in the non-surgical treatment group did not experience any significant deterioration of split renal function, and only about 20% of them underwent secondary surgical intervention, with minor risk of permanent deteriorated split renal function. The study follow-up period was too short to assess the long-term effects on split renal function in both treatment groups. We need further randomised controlled trials with sufficient statistical power and an adequate follow-up period to determine the optimal therapy for newborns and infants less than two years of age with unilateral UPJO.

Read the full abstract...

Unilateral ureteric-pelvic junction obstruction (UPJO) is the most common cause of obstructive uropathy and may lead to renal impairment and loss of renal function. The current diagnostic approach with renal imaging cannot reliably determine which newborns and infants less than two years of age have a significant obstruction and are at risk for permanent kidney damage. There is therefore no consensus on optimal therapeutic management of unilateral UPJO.


To assess the effects of surgical versus non-surgical treatment options for newborns and infants less than two years of age with unilateral UPJO.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 6, 2016), MEDLINE/Ovid, and EMBASE/Ovid databases from their inception to 13 June 2016. We searched the reference lists of potentially relevant studies without using any language restriction. We also searched the following trial registers for relevant registered studies:; ISRCTN registry (;;;; and

Selection criteria: 

We selected randomised and quasi-randomised controlled trials comparing surgical with non-surgical interventions for the treatment of unilateral UPJO.

Data collection and analysis: 

Two review authors independently assessed study eligibility and risk of bias of included studies and extracted data. In case of disagreements we consulted a third review author. The data reported in the two included studies did not allow us to perform a meta-analysis.

Main results: 

We found only two studies at high risk of bias that were eligible for inclusion in this review. The total sample size, including both trials, was small (n = 107 participants less than six months of age from the UK and USA), and not all prespecified outcome measures were assessed. Reported measures only accounted for the short-term follow-ups. The mean split renal function was not statistically different between the surgical and non-surgical group at the six-month or one-year time point (very low-quality evidence). The surgical group showed a significantly less obstructed drainage pattern and a lower urinary tract dilatation than the non-surgical group (very low-quality evidence). Transfer from the non-surgical group to the surgical group was reported for about one out of five participants. Split renal function after secondary surgical intervention was reported with variable results, but most of the participants reverted to pre-deteriorated values. The studies either provided no or insufficient data on the following outcome measures: postoperative complications, UPJO-associated clinical symptoms, costs of interventions, radiation exposure, quality of life, and adverse effects.