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Prenatally detected, unilateral, high-grade hydronephrosis: Can we predict the natural history?

INTRODUCTION
Fetal hydronephrosis (HN) occurs in approximately 5% of pregnancies and its prognosis depends mainly on the grade of the dilation. We attempted to determine the fate of isolated, unilateral, high-grade HN in children with antenatal diagnosis, emphasizing the risk factors for progression.


METHODS
We retrospectively evaluated 424 children (690 kidney units) with antenatal HN in the period between 2010 and 2014. We included only those patients with isolated high-grade HN (Society for Fetal Urology [SFU] Grade 3 or 4). Patients with bilateral HN or unilateral HN associated with dilated ureter or reflux and patients with missed followup were excluded. The prognosis of HN (whether improved, stabilized, or progressed) and the need for surgical intervention in this subset of patients was evaluated.


RESULTS
A total of 44 children (34 boys and 10 girls) were identified. Ultrasounds showed SFU Grade 3 HN in 24 (54%) and SFU Grade 4 HN in 20 (46%). After a mean followup of three years (range 1-5), 10 children (23%) needed surgical intervention; four Grade 3 HN (16%) and six Grade 4 HN (30%). The majority of children with differential renal function (DRF) ≥40% (69.5%) were stable or improved. Five girls (50%) and five boys (17%) progressed and required surgical intervention. No patient with a renal pelvis anteroposterior diameter (APD) <1.5 cm needed surgical intervention.


CONCLUSIONS
Infants with isolated, unilateral, high-grade HN might be managed conservatively. Male gender, DRF ≥40%, SFU Grade 3 HN, and APD <1.5 cm were favourable prognostic factors.