Antenatal hydronephrosis on prenatal US
Recommended: Postnatal Renal Ultrasound at 48 hours-1 week + 4-6 weeks is the preferred imaging study for antenatal hydronephrosis on prenatal us. Most antenatal hydronephrosis resolves.
Recommended study
Postnatal Renal Ultrasound at 48 hours-1 week + 4-6 weeks
Most antenatal hydronephrosis resolves. Etiologies: transient, UPJ obstruction, VUR, ureterocele, PUV, megaureter.
If the default doesn't apply
Differentiating obstructive vs non-obstructive
NM
MAG3 diuretic renogram (after 4-6 weeks of age)
IV contrast
VUR work-up
XR
VCUG
IV contrast
Watch-outs
Bilateral hydroureteronephrosis in boy
Suspect posterior urethral valves — urgent VCUG + urology consultation.
Pearls
- SFU grading 1-4 or Society for Fetal Urology system.
- Antibiotic prophylaxis for moderate-severe hydronephrosis controversial.
- Most transient hydronephrosis resolves by 1 year of age.