The Alpha Fetoprotein (AFP) test is a blood test used in prenatal screening to detect certain abnormalities or conditions in a developing fetus.
The AFP test measures the levels of a protein called Alpha Fetoprotein in the mother's blood. AFP is produced by the developing fetus, primarily by the liver, and it plays a crucial role in fetal development.
The AFP test is typically performed between weeks 15 and 22 of pregnancy, as part of a group of tests known as the second-trimester maternal serum screening.
One of the primary purposes of the AFP test is to screen for neural tube defects (NTDs), such as spina bifida and anencephaly. In NTDs, the neural tube, which eventually develops into the baby's brain, spinal cord, and related structures, does not form properly. Elevated levels of AFP in the mother's blood may indicate an increased risk of NTDs.
In addition to NTDs, the AFP test can provide information about certain other conditions, including abdominal wall defects and chromosomal abnormalities such as Down syndrome. However, it's important to note that AFP alone is not specific enough to diagnose these conditions definitively.
The AFP test results, along with other factors such as maternal age, gestational age, and sometimes additional blood tests, are used to calculate the individual risk of certain abnormalities. The results are typically presented as a screening result with a specific risk factor, such as "1 in 1000" or "1 in 100."
If the AFP test or the combined screening indicates a higher risk of a specific abnormality, further diagnostic tests, such as ultrasound, amniocentesis, or chorionic villus sampling (CVS), may be recommended for a more accurate diagnosis.
