Editor—We were interested in the findings of Jaswon et al regarding the outcome of babies with antenatally detected renal pelvis dilatation (ARPD).1Since October 1997 it has been the practice in our unit to perform micturating cysto-urethography (MCUG) on all babies with ARPD, defined as a fetal antero-posterior renal pelvis diameter of greater than 5 mm,2 even in the presence of a normal six week postnatal ultrasound scan of the renal tract.3

Over the 16 months since this practice has been established, we identified 29 fetuses with ARPD from 3397 total deliveries (0.9%). Twenty four of 29 (83%) had ARPD of 5–10 …