Outcome of fetal pyelectasis diagnosed antenatally

Renal pelvis dilatation is a common anomaly detected at the 20-week anomaly scan. The aim of this study was to evaluate the postnatal outcome of fetal pyelectasis in an unselected obstetric population. This was a retrospective study of fetal pyelectasis detected at midtrimester anomaly scan. Fetal pyelectasis was classified as mild if the anteroposterior renal pelvis diameter measured >5 mm-< or= 7 mm, moderate >7-< or = 10 mm and severe as >10 mm. Persistant fetal pyelectasis was defined as >7 mm in the third trimester.

During the study period fetal pyelectasis was identified in 74 women. 6 were excluded, as case records were not available. Mild pyelectasis was identified in 38/67(56.7%), moderate pyelectasis in 20/67(29.8%) and severe pyelectasis in 9/67(13.4%). None of the infants in the mild pyelectasis subgroup required surgery. 3/29(10%) in the moderate and severe pyelectasis subgroup required postnatal surgery. Of the 38 with mild fetal pyelectasis 13.1% had a positive postnatal diagnosis out of which 7.9% had vesico-ureteric reflux, 2.6% renal dysplasia and 2.6% pelvi-ureteric junction (PUJ) stenoses.

74% of pregnancies in the mild pyelectasis subgroup demonstrated spontaneous resolution. However persistent mild pyelectasis may lead to postnatal morbidity and should be followed up.