[Postnatal investigation and outcome of isolated fetal renal pelvis dilatation]

Abstract

The purpose of this study was to evaluate the prognosis of fetal renal pelvis dilatation in relation to the degree of prenatal dilatation and the postnatal ultrasonography assessment. Based on these results, an algorithm is proposed for the choice of postnatal investigations and follow-up in children with fetal renal pelvis dilatation.

Material and methods: The study was conducted prospectively among 10,677 newborns in Avignon over a nearly 5-year period. Infants with an anteroposterior pelvic diameter (APPD) 5mm or greater in the second trimester were enrolled with a threshold for the normal renal pelvis dimensions increasing with advancing gestation. Prenatal ultrasound was correlated with the results of postnatal investigation and frequency of surgical uropathy was established.

Results: Pyelectasis was found in 1% of pregnancies and among 100 infants whose cases were followed, 23 (23%) had uropathies (seven isolated pelviureteric junction obstruction [PUJ], nine isolated vesicoureteral reflux [VUR], three VUR+PUJ, two duplicity, one obstructive megaureter, and one multicystic dysplastic kidney). The largest group of fetuses (66/100) had minor fetal pyelectasis of less than 10mm: in this group, 90% of the infants had no uropathy and there was no surgery. Six of 34 (17%) in the moderate (APPD> or =10 and<15mm) and severe (APPD> or =15mm) fetal pyelectasis groups required surgery, especially those with progressive PUJ obstructions. When postnatal ultrasound was normal in 64 infants (64%), there were only three mild or moderate (grades I-III), asymptomatic, and spontaneously resolving VUR. When pyelectasis was isolated and 10mm< or =APPD<15mm, cystourethrography was normal in 70% of the cases and only four cases of spontaneously resolving VUR were found. Among 23 infants with uropathies, six of 23 required surgery (26%), especially PUJ stenosis (5/6) with APPD greater than 15mm. In the total population of fetal pyelectasis, postnatal ultrasound predicted renal abnormalities with a sensitivity of 87% and a negative predictive value of 95%.

Conclusion: Normal neonatal ultrasound rarely coexists with significant abnormal findings and there seems to be no need for additional investigations when postnatal echography is normal. Cystourethrography can be delayed when pyelectasis is isolated with 10mm< or =APPD<15mm. Isolated and uninfected cases of VUR do not require surgery and all mild and moderate cases of VUR spontaneously resolved. All PUJ stenoses with APPD greater than 15mm required surgery.