Which quad screen results indicate high risk for Down syndrome?

The quad screen is a maternal serum screening test that assesses the risk of certain conditions, including Down syndrome, during pregnancy. It measures four specific markers: alpha-fetoprotein (AFP), estriol, human chorionic gonadotropin (hCG), and inhibin A.

In the case of Down syndrome, a typical pattern seen in the quad screen results is a combination of low AFP, low estriol, high hCG, and elevated inhibin A. This pattern reflects the way that placental and fetal metabolism changes in pregnancies affected by Down syndrome.

Low levels of AFP and estriol suggest a potential developmental issue, while high levels of hCG and inhibin A further heighten the concern for trisomy 21 (Down syndrome). The elevations in hCG and inhibin A occur due to the placental alterations associated with the condition, making these hormone levels pertinent in evaluating risk.

Understanding this pattern is crucial for interpreting quad screen results effectively and recognizing when further diagnostic testing, such as amniocentesis or chorionic villus sampling, may be warranted for a more definitive assessment.