Utility of ultrasonography in the diagnosis of autosomal dominant polycystic kidney disease in children.

To determine the utility of ultrasonography (US) in diagnosing autosomal dominant polycystic kidney disease (ADPKD) in children, this study examined 106 children who were at 50% risk for the disease. The children underwent a history, physical examination, abdominal US, and gene linkage analysis (GLA) with tightly linked markers for ADPKD1 and ADPKD2 genes. Only ADPKD1 children were studied. A child was considered affected by US if any cysts were detected and affected by GLA if he or she shared the same haplotype as the affected parent. Forty-two children (40%) were considered to be unaffected by both GLA and US. Forty-eight children (45%) were considered affected by both modalities. Only two of these children had a single cyst. Fourteen children (13%) were considered affected by GLA with normal initial US. These children tended to have larger kidneys than children who were unaffected by GLA. Eight of these 14 children had subsequent positive ultrasonograms. Two children had a positive ultrasonogram with GLA showing them to be unaffected; in one of these children, a subsequent ultrasonogram was interpreted to be normal with a medullary pyramid. Thus, overall the false negative rate was 25%, and the false positive rate was 2%. The false negative rate was highest in the children who were 3 months to 5 years of age (38%). Clinicians must understand the utility of US in diagnosing ADPKD in at-risk children and must not interpret a normal study as absence of disease in this population.