ABSTRACT
Clinical attention may be drawn to the renal tract in a number of different ways in the neonate. With better ultrasound equipment, and more prenatal ultrasound (US) examinations, a large group of neonates are presenting with an antenatal diagnosis of a nephrourological abnormality. The neonate may also present ill with septicemia and/or a urinary tract infection (UTI), with a metabolic upset due to renal failure, or simply vomiting. Occasionally the ill neonate may have hematuria due to renal venous thrombosis, especially if the infant was subjected to any hypoxic event, i.e. prolonged labor. A well neonate may present with an abdominal mass found on routine examination or with an unrelated congenital abnormality, e.g. esophageal atresia. Once the renal tract has been brought to the attention of the clinician, the role of the radiologist/ imager is to establish the number and size of the kidneys. Further, it needs to be established if the infant was born with a normal tract and is suffering from an acquired condition, e.g. renal vein thrombosis, or whether there is an underlying congenital developmental abnormality. The questions posed by the clinical team are: first, how many kidneys are present; second, is there dilatation of the collecting system; third, is the bladder normal or is there a thick bladder wall; and finally, what is the state of individual renal function? The answers come from a combination of abdominal US examination, micturating cystourethrography (MCU), technetium-99m dimercaptosuccinic acid (99mTc-DMSA) scan and/or Tc-99m mercato acetyl triglycine (99mTc-MAG3) scan. A logical approach to these imaging techniques should be established in an attempt to reach the diagnosis using the lowest radiation dose and least invasive technique. There is almost no indication for intravenous urography (IVU) or computerized tomography (CT) in the neonatal period; the role of magnetic resonance imaging (MRI) has yet to be established.
