Both levels of ultrasound should be performed by those experienced in sonography. Such expressions do not address the degree of risk to the individual patient. As data are collected to permit an estimate of risk in subpopulations whose members are comparable to the woman being screened, laboratories should include in the laboratory report information about the risk to the woman on the basis of her test result. Pregnant women with IDDM should be considered as a separate category. AFP levels are lower, on average, for women with IDDM, and this should be taken into consideration when interpreting results.
Higher volume assures better quality control.
To accomplish this, screening should be centralized, especially in areas of low population density. At frequent intervals, laboratories should review the most recent results, compare them to previous results to ascertain changes in the median and dispersion of values, and investigate the causes of variation. The appropriate state agency should qualify or license laboratories to perform the specific assays. States or regions lacking such certification programs should establish them. The laboratory report should contain a quantitative expression of the AFP level or patient-specific risks for relevant genetic anomalies and conditions.