Dysplastic kidney disease is common, occuring as unilateral disease in 1 in 1000 births and bilaterally in 1 in 5000. It is the common cause of an abdominal mass in the newborn. The condition typically is diagnosed on prenatal ultrasonography. The kidney is highly echogenic or “bright”, with multiple large, thin-walled cysts that typically are seen by 20 weeks gestation, in dystiction from polycystic disease. These cysts characteristically separate and distributed randomly througout the renal parenchyma. Grossly, the kidneys are dysplastic, with little normal architecture evident, and the multiple large cysts are easily throughout the entire organ. Most often, an affected kidney is significantly enlarged, and this large irregular mass may be easily palpated in the newborn. Both the cysts and overall enlargement may become more pronounced as gestation proceeds, but many dysplastic kidneys involute, even during the prenatal period. Unlike cases of obstruction of the lower collecting systems, it can be difficult to identify the renal pelvis or ureter on ultrasonography.
Bilateral disease frequently is severe, and the prognosis typically poor, with progression to severe oligohydramnios and pulmonary hypoplasia, resulting in Potter sequence, and a low likelihood of survival after birth. This outcome usually associated with findings of either marked renal enlargement or involution during late pregnancy. Some cases of bilateral disease are less severe and survival is possible. Dialysis is necessary for chronic renal failure in affected children, and their require specialized care for nutrition. As the children grow, renal transplantation becomes a possibility.
Unilateral disease usually presents with no specific signs or symptoms in the neonate, other than the presence of a large abdominal mass, which rarely can cause mechanical problems. If it is, of course, diagnosed typically on prenatal ultrasonography
Following a prenatal diagnosis, postnatal ultrasonography should be undertaken to rule out associated urinary tract anomalies and to confirm the original diagnosis. Many practitioners recommend waiting for at least 1 week after birth to perform this study to avoid false-negative results due to normal oliguria, but others have found that studies performed as early as 48 hours after birth are reliable, especially if repeated at about age 6 weeks.
The major risk is the development of chronic renal failure, which develops in 12% to 50% of patients who have apparently normal contralateral kidneys. Serum creatinine is monitored routinely to identify developing renal failure. Hypertension is uncommon occurence, and blood pressure monitoring is recomended only as part of regular care.