P14.84: Fetal pyelectasis and prediction of post-natal renal abnormalities

The aim of this study was to determine the degree of renal pelvic dilatation that offers the best diagnostic accuracy in predicting post-natal renal pathology; and also evaluate which trimester was more sensitive in predicting postnatal renal outcome. We observed 83 patients with diagnosis of fetal pyelectasis and gestational age between the 20th and 38th. In 80 cases (96%), this abnormality was isolated. For each pregnancy, between two to five ultrasonographic controls were performed. All neonates were screened using ultrasound and later eventually underwent cystourethrography, DMSA scintigraphy and isotopic DTPA renogram to diagnose the pathology and therefore determine its treatment. In 56% of the kidneys controlled postnatally, pyelectasis was confirmed. 16% required surgery. Fetal pyelectasis was on average 5.6 mm, in the II trimester and 6.0 mm in the III trimester for the cases that failed to be confirmed postnatally while for those managed conservatively, it was of 7.4 mm in the II trimester and 10.0 mm in the III trimester. In those who required surgery it was 11.7 mm in the II trimester and 17.8 mm in the III trimester. The statistical comparison of the ROC curves showed a higher reliability of the III trimester sonographic measurements in predicting both those cases that will not persist postnatally and those who will require surgery compared to the II trimester measurements. The diagnostic accuracy during the III trimester in predicting the necessity for surgery did not result statistically different for 9 (71%), 10 (75%), 11 (81%) and 12 (84% mm but was definitely higher when compared to the 8 (67%), 7 (55%) and 6 (46%) mm. On the contrary, the 8 and 9 mm thresholds seem to better predict those cases that will not persist postnatally with an accuracy of 81%. Prediction of the postnatal outcome for those cases with pyelectasis can best be obtained from III trimester biometry using either 10, 11 or 12 mm for predicting those cases that will require surgery.