The first important step in managing patients with prenatal findings of decreased amniotic fluid, genital malformations, or other serious anomalies is to have the child treated in a tertiary care center for delivery and management of neonatal issues. Upon delivery, a directed physical examination is important to rule out associated anomalies. A newborn ultrasound will be performed at a minimum of 48 hours of life to one month. Depending on these results, the urologist may order an x-ray test called a VCUG, which involves instilling dye into the bladder and taking x-rays while the child empties the bladder. This test helps to look for bladder abnormalities and the presence of urinary reflux.
In most cases, postnatal evaluation can be performed on an outpatient basis. Children with moderate degrees of prenatal hydronephrosis can be discharged home on amoxicillin with no further inpatient evaluation. Generally an ultrasound is not performed in the first two days of life, as the neonate is usually dehydrated, creating the potential to underestimate hydronephrosis. The first ultrasound can be performed after 3-4 weeks on an elective basis while the child continues antibiotic prophylaxis.
When the postnatal ultrasound reveals severe pelvic dilation (over 1.2 cm) and caliectasis, diuretic renography is needed to assess the degree of renal obstruction and to assess renal function. Ideally, the renography is performed after the infant is at least one month of age. 99mTc MAG-3 is the radionuclide agent of choice.
