Maternal serum alpha-fetoprotein screening for fetal Down syndrome in the United States: results of a survey

Article Abstract:

High levels of alpha-fetoprotein (AFP) in the blood of pregnant women can indicate fetal Down's syndrome (a genetic abnormality that causes mental retardation) or defects in the fetal neural tube, which develops into the brain and spinal cord. The criteria used in diagnosing AFP abnormalities vary among laboratories. The status of screening for alpha-fetoprotein in the blood of pregnant women was determined by asking 109 laboratories what criteria they use to determine high risk for Down's syndrome. Out of the 96 laboratories providing criteria, 85 used a combination of AFP values and the age of the mother to help determine the risk for Down's syndrome and 11 used a fixed cut-off level of AFP. In 25 percent of the pregnancies, ultrasound, the use of high frequency sound to visualize the fetus, was used to determine the actual age of the fetus in weeks. The overall percentage of women classified as high-risk was 3.7 percent. If the age-specific risk profile is not used, many women could be misclassified. The AFP levels measured by enzyme immunoassay kits were lower (3.0 percent) when compared with radioimmunoassay techniques (4.8 percent). Although the overall performance of laboratories was satisfactory, some laboratories may need to improve methods of assigning risk by including the accurate aging of the fetus to be used in combination with AFP levels. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Medical screening, Health screening, Alpha fetoproteins

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Lack of an association between late fetal death and antiphospholipid antibody measurements in the second trimester

Article Abstract:

A few studies have indicated that pregnant women who test positive for high levels of antiphospholipid antibodies have a much higher risk for pregnancy complications such as preterm delivery or fetal death. Only one of these studies was performed in a general obstetric population. To further examine this issue, a case control study was performed in a large, general obstetric population. Stored blood serum from 309 pregnancies that had nonviable outcomes was tested for antiphospholipid antibodies as was serum from 618 viable pregnancies, two controls matched to each nonviable pregnancy. Matching was based on gestational age at time of sampling and date of sampling. All pregnancies had reached at least 15 weeks' gestation. The sera had been obtained from pregnant women who underwent routine maternal alpha-fetoprotein screening. Antiphospholipid antibody levels were similar in both groups of women. Highly elevated levels of one type of such antibodies was found in only one of the women who had a nonviable pregnancy outcome. Other, well-established factors associated with fetal death were similarly distributed in this group, as has been previously reported. The results indicated that there is no association between late fetal death and maternal antiphospholipid antibody levels. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Risk factors, Pregnancy, Complications of, Pregnancy complications, Antiphospholipid antibodies, Fetal death

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Maternal serum screening for Down syndrome in the United States: a 1995 survey

Article Abstract:

Down syndrome screening conducted by laboratories may be more effective if multiple markers are used and testing is performed after 14 weeks of pregnancy. Researchers surveyed 265 laboratories providing Down syndrome screening to an annual total of 2.5 million women. Most laboratories provided screening for both Down syndrome and open neural tube defects. More laboratories were using multiple blood tests for Down syndrome in 1995 than in 1992. Screening for Down syndrome at 13 weeks of pregnancy or earlier was found to be inconclusive and should wait until at least 14 weeks.

Surveys, Prenatal diagnosis

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