Editor—I read with interest the study by Jaswonet al on outcome in antenatally diagnosed renal pelvis dilatation.1

The cohort was recruited antenatally from pregnancies where renal pelvis dilatation had been diagnosed mostly on the 20 week ultrasound scan. VUR was described as being “the most common clinically significant pathology” (23 out of 104 cases). Presumably all of the babies were asymptomatic. How can the authors be sure that this VUR was either clinically significant or indeed pathological?

Figure 2 shows that nine out of 23 babies had grade III or IV VUR despite a normal postnatal renal ultrasound scan. Is anything known of the natural history of these nine babies? The reference regarding the possible prevalence of VUR in infants is a “literature review”2 (method not stated by the author) of 14 papers published between 1916 and 1967—that is, predating the era of antenatal ultrasonography.

One baby went on to have pyeloplasty at 18 months of age, because of deteriorating renal function, due to PUJ obstruction, not VUR (table 1). This low rate of surgical intervention (one baby out of 139 pregnancies over 18 months) reinforces the notion that these findings are largely benign.3]

The longer term follow up, or outcome, of the other 103 babies is not stated—for example, if the postnatal renal ultrasound scan and MCU were normal, n=60/104, the infant was discharged. This suggests follow up only of babies with “abnormal” findings.

Information has been collected regarding the prevalence of VUR, PUJ obstruction, and renal dysplasia in the first three months of life in this cohort. What is the evidence that these diagnoses have clinically important long term adverse outcomes?

The conclusion states that babies with antenatal renal pelvis measurements of 5 mm or greater should be investigated, as they may have VUR. However, I am unclear as to what long term outcome measures will be improved by these sometimes invasive investigations.

Table 1 also contains data on 25 babies, but the text refers to persisting renal pelvis dilatation in 47 babies.