Final answer:
Maternal serum alpha-fetoprotein (MSAFP) screening is a blood test in pregnancy for detecting fetal abnormalities by measuring alpha-fetoprotein levels. It is performed during the second trimester, between 15 and 20 weeks of gestation.
Step-by-step explanation:
What is Maternal Serum Alpha-Fetoprotein (MSAFP) Screening?
Maternal serum alpha-fetoprotein (MSAFP) screening is a blood test performed during pregnancy to assess the level of alpha-fetoprotein (AFP) in a mother's blood. AFP is a protein that is normally produced by the fetal liver and is present in the fluid surrounding the fetus (amniotic fluid). The AFP passes into the mother's blood, and the MSAFP test measures the amount of AFP that has done so. Elevated or decreased levels of AFP can indicate certain conditions in the fetus, such as neural tube defects like spina bifida or anencephaly, or chromosomal abnormalities such as Down syndrome. However, abnormal AFP levels can also be influenced by other factors such as multiple pregnancies or inaccurate dating of the pregnancy.
When is the MSAFP Screening Performed?
MSAFP screening is usually performed during the second trimester of pregnancy, between 15 and 20 weeks of gestation. This timeframe provides the most accurate information from the AFP levels measured in the mother's serum. It is often part of a larger panel of tests known as the 'multiple marker screen' or 'quad screen' which also measures hormones and protein substances indicating the health and development of the fetus.
Tissue-specific markers like AFP are utilized in different contexts, including monitoring cancer survivors. For example, an elevated AFP in a child previously treated for teratoma might suggest a relapse of an endodermal sinus tumor.