PRENATAL DETECTION OF NEURAL-TUBE DEFECTS BY MATERNAL SERUM ALPHAFETOPROTEIN ASSAY - A PILOT-STUDY USING ENZYME-LINKED IMMUNOSORBENT-ASSAY

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 60  (8) , 319-324
Abstract
Mass screening for fetal neural tube defects using maternal serum enzyme-linked immunosorbent .alpha.-fetoprotein assay as the initial test is financially justified in South Africa, despite the relatively low incidence of these defects in this country. This technique is efficient and inexpensive and lends itself to mass screening. A pilot study in which 3153 maternal serum samples were received during a 4-mo. period is reported. Of these, 3102 were assayed and the outcome of pregnancy was recorded in 2069 cases. On the 1st asaay, 147 (4.7%) of the women had serum .alpha.-fetoprotein levels which were high for the gestational dates given, but in retrospect about half of these were misinterpreted because of incorrect dates. Among the remainder, 6 women were carrying twins, 4 aborted spontaneously, 10 delivered prematurely or had infants with intrauterine growth retardation, and 4 had a fetus with a neural tube defect. Two affected fetuses were missed by screening, in both cases because serum was taken after 20 wk gestation. In this sample the incidence in Indians (1/1000) and Negroes (1/600) was as expected but in Caucasians it was much higher (1/130), which probably reflects a sampling error and indicates that the epidemiology of neural tube defects in South Africa requires investigation.