What are included in the first trimester screening tests?

The first trimester screening tests are primarily designed to assess the risk of certain chromosomal abnormalities in the fetus, such as Down syndrome (trisomy 21) and trisomy 18. A critical component of this screening is the measurement of pregnancy-associated plasma protein A (PAPP-A). PAPP-A is a protein produced by the placenta and is often measured in conjunction with other markers during this early stage of pregnancy.

When screening is conducted, PAPP-A levels, along with the maternal age and other ultrasound findings, help to calculate the risk of chromosomal abnormalities. Abnormal levels of PAPP-A may indicate an increased risk for complications, prompting further diagnostic testing if necessary.

In contrast, cervical cultures are not part of the first trimester screening tests and are typically performed later in pregnancy to check for infections. The glucose tolerance test, which is used to assess gestational diabetes, is usually conducted in the second trimester. Transabdominal ultrasound can be utilized for various purposes but does not specifically pertain to first trimester screening tests related to chromosomal abnormalities. Therefore, PAPP-A is clearly central to the first trimester screening process, confirming its role as a key marker in evaluating potential risks during early pregnancy.