Investigating cases of hydronephrosis

Bilateral fetal hydronephrosis or a hydronephrotic single kidney with APRPD greater than 10 mm

  • Should be initially evaluated by ultrasonography on the first to second postnatal day.
  • Could be a finding of bladder outlet obstruction such as ureterocele, or posterior urethral valves (PUV) in a male infant.
  • In these infants, the risks of impaired renal function and renal injury are high.

The severity of postnatal hydronephrosis

When to look:
Ultrasound should be performed after 48 hours of life in a full-term infant to help in detecting hydronephrosis.

What to look for:
Based on anterior-posterior pelvic diameter (APRPD) +/-calyceal dilation and renal parenchymal thinning:
- Normal or mild hydronephrosis - APRPD<10 mm
- Moderate hydronephrosis- APRPD 10-15 mm
- Severe hydronephrosis- APRPD >15 mm is the greatest risk for significant renal disease requiring surgical correction

How to classify the risk:

Obstructive uropathies | 2. Diagnosing obstructive uropathy
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