Paediatrics: Congenital urinary tract anomalies

Congenital urinary tract anomalies

·  Increasingly, urinary tract anomalies are being detected earlier by the use of routine antenatal ultrasound scans.

·  Renal anomalies account for about 20% of all significant abnormalities found on detailed scans at 18–20wks gestation.

·  Close liaison between obstetricians, paediatrician, and surgeon with regard to counselling the parents and follow-up is vital.

·  Centres should have a postnatal investigation protocol as the majority of infants will be asymptomatic.

Amniotic fluid volume

·  Oligohydramnios: low urine production or obstruction of urine excretion that may lead to pulmonary hypoplasia.

·  Polyhydramnios: polyuria.

Renal size

·  Enlarged: cystic kidneys (any cause); hydronephrosis.

·  Small: dysplasia.

Hydronephrosis

Unilateral: pelviureteric junction (PUJ) or vescioureteric junction (VUJ) obstruction; vescioureteric reflux (VUR).

·  Bilateral: bladder outlet obstruction, e.g. PUV, VUR, prune belly syndrome.

Renal cysts

·  Multicystic dysplastic kidneys (MCDK).

·  Polycystic kidney disease (PCKD).

·  Cystic dysplasia.

Abnormal renal parenchyma

Echogenic:

·  cystic kidneys (any cause);

·  congenital nephrotic syndrome (may have polyhydramnios, large placenta).

Investigations

If a major problem is suspected (e.g. PUV, bilateral severe hydronephro-sis, palpable kidneys), a renal US should be performed after 24hr of age. Otherwise routine postnatal investigation with U/S (at 2–4wks), MCUG (at 4–8wks), and radionuclide scan (at 8–12wks of age).

Clinical management

In the postnatal period, ensure male infants have voided and that a good urinary stream is observed. The initial postnatal US finding guides further management.

·MCUG only routine if strong suspicion of VUR (e.g. dilated ureters/ intermittent dilatation of pelvis). Will need cover with antibiotics (e.g. oral trimethoprim) for the procedure.

·Give antibiotic prophylaxis (e.g. oral trimethoprim) to all babies with suspicion of VUR.

·Radionuclide scan depends upon lesion:

·  DMSA if function of kidney required (e.g. MCDK, VUR);

·  MAG-3 renogram if ‘obstruction’ being evaluated (e.g. PUJ, VUJ).

Most infants with hydronephrosis can be conservatively managed if they are asymptomatic.