I read with interest the report by Plant et al,¹ in which it is suggested that children with an antenatal renal pelvic diameter of 5–15 mm do not require postnatal investigations or treatment, as their rate of renal scarring with dimercaptosuccinic acid (DMSA) after the age of 4 years (1/189 children) was 0.5% (95% confidence interval (CI) 0 to 2.9) for both sexes combined. It is not clear, however, if their results represent antenatal renal dilatation diagnosed at 20 or 28 weeks gestation; as more than half of such findings subside between 20 and 28 weeks, the resulting calculation of prevalence of abnormalities could vary by a factor of at least 2 if the cases they reported were diagnosed at 20 weeks gestation.

Their results contrast with our findings, here described. Over a five year period, out of 355 children with antenatal pelvic dilatation at 20 weeks gestation, 137 children were found to have an antenatal renal pelvic diameter of …