Outcome in antenatally diagnosed renal pelvis dilatation

Editor—Dr Nicholl raises some pertinent points in his letter1 regarding our paper.2 The nub of the matter is whether asymptomatic vesico-ureteric reflux (VUR), detected as a result of antenatal ultrasound findings is clinically important or not. The answer to this question is not yet known and will require a trial that looks at what, if any, difference treatment makes to outcome, as judged by the development of renal scars.

Until this matter is resolved, however, we feel it appropriate to look for VUR when there has been antenatal renal pelvis dilatation, and treat accordingly. As stated in our study,1 this judgement is partly based on the fact that the prevalence of asymptomatic VUR is around 1%, as described by Bailey, in contrast to an incidence of 20% in our study, implying that our findings were significant.

We accept that in a review of the published findings, from which Bailey acquired his data, the radiological techniques used may have differed from those currently in use, but as can be imagined, it is not easy to acquire information about the incidence of VUR in healthy children, and Bailey's work is, to our knowledge, the currently accepted reference.2

With regard to the specific points raised by Nicholl around 50% of the babies with VUR in our study, have now undergone further imaging at the age of 3 years. Their reflux had resolved and, more importantly, no renal scarring had been incurred. In those babies where both postnatal ultrasonography and the micturating cystogram were normal, the infants were discharged from further follow up, as we saw no further indication for continuing their surveillance.

The fact that only one baby required surgical intervention reflects that VUR, which is generally treated medically, was the most common finding, and a more conservative approach is now adopted in cases of pelvi-ureteric junction obstruction.

In table 1 of our study we included, under the diagnosis of “idiopathic dilatation” only those infants in whom persisting renal pelvis dilatation was > 10 mm, because in those (n=22) in whom it was 5–10 mm and the micturating cystogram was normal, we did not feel an MAG III renogram was indicated; therefore, they did not strictly fulfil our criteria for this diagnostic label.