An Alpha feto protein blood test is one of the many screening blood tests performed during pregnancy. Alpha fetoprotein (AFP) is the protein produced by the yolk sac and liver of the fetus and is secreted in the mother's blood. This test measures the amount of Alpha fetoprotein in the mother's blood and can be used to see if the fetus is at risk of serious birth defects. It cannot however, diagnose the specific defect. An AFP test may also be done as part of other screening tests to look for other chromosomal abnormalities such as Down's syndrome or Edward's syndrome. Outside pregnancy, this test can be performed on persons to find certain cancers. Most people with liver cancer do not have high AFP levels. The test could also be conducted to see how well the cancer treatment is working in such people.
This Alpha feto protein blood test is usually performed between the 15th and 20th week of pregnancy. Most doctors carry this out at week16. Blood is drawn from the mother and results are available after a week. AFP can also be measured in the amniotic fluid during amniocentesis. The AFP level is checked during the triple or quadruple screening test.
The test results are usually given in terms of percentages. For example, the report might read -Risk of Neural Tube Defect 1 in 200.
Abnormal results or high levels of AFP in pregnancy will be due to the following problems:
- Neural tube defects - defects of the spine or the brain (spina bifida, anencephaly).
- Turner syndrome
- Low birth-weight fetuses
- Duodenal atresia
- Multiple pregnancy (twins, triplets)
- Some renal and urinary tract anomalies
- Omphalocele - a congenital condition where the baby's intestines protrude from the stomach wall.
- Tetralogy of Fallot
- Intrauterine death (usually results in a miscarriage)
- Inaccurate due date.
When an abnormal result is found, the woman will usually be asked to go for an ultrasound. The fetus will be examined to see if there are abnormalities. If none can be found during the ultrasound then an amniocentesis is the next step. The risk with amniocentesis is that there is a slight chance of a miscarriage occurring after it is done. There is no risk associated with the test itself or a subsequent retest. However, there is a risk of a false positive result. This is when the baby has a problem but the test does not show it and it appears that the baby is healthy.
Think carefully before having this test or a retest done as the information it will give you will perhaps result in some painful decisions about your pregnancy.
Submitted by M H on April 14, 2010 at 12:32