First-trimester biochemical screening includes which components?

First-trimester biochemical screening includes which components?

• A. Amniocentesis only
• B. Quad screen
• C. Free beta-hCG and PAPP-A with ultrasound
• D. Glucose tolerance test

Answer: (C)

The main idea being tested is how early screening estimates fetal aneuploidy risk by combining maternal serum markers with ultrasound findings. In the first-trimester screen, the assessment uses measurements of free beta-hCG and pregnancy-associated plasma protein A (PAPP-A) in the mother's blood, together with an ultrasound assessment of fetal nuchal translucency. This combination, usually done around 10 to 13 weeks, provides a risk estimate for chromosomal abnormalities such as Down syndrome. The typical pattern in Down syndrome is higher free beta-hCG and lower PAPP-A, with an increased nuchal translucency on ultrasound, all contributing to a higher risk estimate. Amniocentesis is a diagnostic test that provides direct fetal karyotype information, not a screening component. The quad screen is a second-trimester test using different serum markers. The glucose tolerance test screens for gestational diabetes and is not part of first-trimester aneuploidy screening.

The main idea being tested is how early screening estimates fetal aneuploidy risk by combining maternal serum markers with ultrasound findings. In the first-trimester screen, the assessment uses measurements of free beta-hCG and pregnancy-associated plasma protein A (PAPP-A) in the mother's blood, together with an ultrasound assessment of fetal nuchal translucency. This combination, usually done around 10 to 13 weeks, provides a risk estimate for chromosomal abnormalities such as Down syndrome. The typical pattern in Down syndrome is higher free beta-hCG and lower PAPP-A, with an increased nuchal translucency on ultrasound, all contributing to a higher risk estimate.

Amniocentesis is a diagnostic test that provides direct fetal karyotype information, not a screening component. The quad screen is a second-trimester test using different serum markers. The glucose tolerance test screens for gestational diabetes and is not part of first-trimester aneuploidy screening.