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Published on: July 18, 2025
[Postnatal investigation and outcome of isolated fetal renal pelvis dilatation]
1Service de néonatalogie, hôpital Henri-Duffaut, 305, rue Raoul-Follereau, 84902 Avignon cedex 9, France. PMasson@ch-avignon.fr
Insights
Fetal renal pelvis dilatation prognosis depends on prenatal measurements and postnatal ultrasound. Minor dilatation rarely requires surgery, while severe cases and specific obstructions necessitate intervention, guiding postnatal investigation strategies.
Area of Science:
- Pediatric Urology
- Fetal Medicine
- Diagnostic Imaging
Background:
- Fetal renal pelvis dilatation (FRPD) is a common prenatal finding.
- Accurate prognosis is crucial for appropriate postnatal management and avoiding unnecessary investigations.
Purpose of the Study:
- To evaluate the prognosis of FRPD based on prenatal dilatation degree and postnatal ultrasound.
- To propose an algorithm for postnatal investigations and follow-up in affected infants.
Main Methods:
- Prospective study of 10,677 newborns over 5 years.
- Enrollment of infants with anteroposterior pelvic diameter (APPD) ≥5mm in the second trimester.
- Correlation of prenatal ultrasound findings with postnatal investigations and surgical uropathy rates.
Main Results:
- Pyelectasis occurred in 1% of pregnancies; 23% of followed infants had uropathies.
- Minor fetal pyelectasis (<10mm) rarely led to uropathy or surgery (90% no uropathy).
- Severe dilatation (APPD ≥15mm) and progressive pelviureteric junction obstruction (PUJ) often required surgery (17% in moderate/severe groups).
- Normal postnatal ultrasound had a high negative predictive value (95%) for significant abnormalities.
- Postnatal ultrasound sensitivity for renal abnormalities was 87%.
Conclusions:
- Normal neonatal ultrasound findings suggest no need for further investigations.
- Cystourethrography can be deferred for isolated pyelectasis with APPD 10-15mm.
- Isolated, uninfected vesicoureteral reflux (VUR) and mild/moderate VUR cases often resolve spontaneously and may not require surgery.
- All cases of pelviureteric junction stenosis with APPD >15mm required surgical intervention.
Unlabelled:
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.
