Antenatal USG evaluation includes- Serial measurements of renal pelvic AP diameter every 4-6 weekly from 16th week onwards(>10mm significant),
- Dilation of calyces, ureters
- Echogenicity of renal parenchyma
- Contralateral kidney size, dilation
- Bladder size and thickness
- Emptying time; urine flow
- Amniotic fluid volume( oligohydramnios means poor fetal renal function)
- Posterior urethral dilation
Antenatal USG evaluation of
HDN can detect the above mentioned causes, which need confirmation postnatally by clinical evaluation, micturating cystourethrography (MCU), radionucleide Tc99DTPA or MAG renal scan.
Postnatal At birth:
evaluation of hydronephrosis
Clinical examination to observe urinary stream (poor in PU valves), renal masses, distended bladder which is firm in PU valves, abdominal wall muscles, undescended testes (Prune belly syndrome). (In suspected PU valves - immediate catheterisation is required to drain the urinary bladder and relieve back pressure).
USG, MCU, serum creatine / BUN (to be repeated after 6 weeks of relief of obstruction to evaluate effect of obstruction on renal function).