Afp Pregnancy

Screen test blood from the mother - AFP or Triple

Another screening procedure requires only small sample of blood of pregnant women, hence its consideration as a noninvasive technique. Collecting blood samples from the mother allows the measurement of certain chemicals that have elapsed since the fetus in amniotic fluid and the placenta into the maternal circulation. A screening test does not allow a definitive diagnosis, it indicates an increased possibility that the condition is present. blood tests of the mother can screen for open neural tube defects and developmental genetic disorders, including Down syndrome or trisomy others. abnormal values of these chemicals suggest that parents consider other tests show a defect in the fetus.

Alpha-fetoprotein (AFP) is a protein present in all fetuses. When the fetus has unusual openings in the skin, such as characterize the open neural tube defects (NTDs a) as spina bifida, the level of this protein in amniotic fluid and maternal blood is abnormally high. In these defects, which are in early pregnancy and following a failure of structures that become the brain and spinal cord to close properly, nervous tissue is outside the body. NTDs cause a variety of problems, from mild to severe.

Maternal blood is tested between 15 and 20 weeks of pregnancy. The test is sometimes abbreviated as MSAFP, standing for maternal serum alpha-fetoprotein. The protein is actually measured in serum or liquid portion of blood from the mother, separated from the laboratory of solid substances in the blood such as red blood cells and white blood.

There is no absolute amount of AFP in maternal blood that positively identifies NTD. The amount is reported as a mother-multiple of the mean for gestational age. This represents how far from the mean or average of the measured value of AFP falls. The analysis takes into consideration other factors that influence AFP, including maternal weight, race, and if she has diabetes mellitus or carrying more than one fetus (if known). The cut score that indicates the risk of missing some real NTDs as possible, but the majority of fetuses whose mothers show a high value are not lacking.

MSAFP will be accurate in showing a neural tube defect in 80 to 85 percent of fetuses who actually have defects, but that 90 percent of fetuses whose AFP screening test shows an elevation will prove to be normal. This is called a false positive result.

Elevated AFP is the reason for the ultrasound study of fetal central nervous system to find a neural tube defect or other anomalies associated with an increased level of maternal AFP. As AFP normally increases each week between 15 and 20 weeks of pregnancy, an elevated AFP could be due to an error in dating the pregnancy, so gestational age is actually higher than that calculated by the last menstruation. This can be determined by ultrasound and AFP value reinterpreted according to the revision of the gestational age. Multiple pregnancies can also cause increased levels of AFP mother. Ultrasound is very accurate in the confirmation of multiple pregnancy. Other fetal abnormalities associated with elevated AFP and demonstrable impact on the sonogram include fetal death and abnormalities in the formation of the fetal abdominal wall and umbilical cord. Anencephaly, a neural tube defect in which the skull is missing, can be definitively diagnosed by ultrasound, but other neglected tropical diseases can be missed.

At the other extreme, an unusually low concentration of AFP in maternal serum may be associated with a trisomy. This must be confirmed by amniocentesis, although sometimes a full sonogram performed well may find abnormalities that are strongly indicative of Down syndrome. The accuracy of these sonograms.