How is mild or moderate unilateral antenatal hydronephrosis treated?

Updated: Dec 16, 2020
  • Author: Dennis G Lusaya, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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In newborns with less severe antenatal unilateral hydronephrosis (renal pelvic diameter < 15 mm during third trimester), ultrasonography can be performed after age 7 days to see whether the hydronephrosis has persisted postnatally.

Moderate hydronephrosis resolves by age 18 months in most cases. This was illustrated by a prospective study of 282 infants (age 2 mo) with renal pelvic diameters between 10 and 15 mm, which resolved in 94% of patients by age 12-14 months (resolution was defined as renal pelvic diameter ≤5 mm on two consecutive ultrasounds). Of the 18 patients with persistent hydronephrosis, 14 had ureteropelvic junction (UPJ) obstruction and 4 had vesicoureteral reflux (VUR). [29]

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