In the context of Quad screen, how are Trisomy 18 results interpreted?

In the context of the Quad screen, the interpretation of Trisomy 18 results is characterized by specific patterns of the biomarkers measured. Trisomy 18, also known as Edwards syndrome, is associated with distinct findings where alpha-fetoprotein (AFP) and estriol (E3) levels are both low, while the human chorionic gonadotropin (HCG) level is also low. This combination of markers indicates an increased risk for the condition.

The low levels of AFP and E3 suggest that the fetus is not producing these hormones at normal levels, which is consistent with the developmental abnormalities seen in Trisomy 18. Additionally, the low level of HCG supports the possibility of this chromosomal disorder, as the elevation in HCG seen in other conditions, like Down syndrome (Trisomy 21), is not present.

When interpreting results from the Quad screen, it’s crucial to recognize that these patterns help to assess the risk for chromosomal abnormalities, guiding further diagnostic testing or counseling for expectant parents. Thus, the interpretation that shows low AFP, low E3, and low HCG aligns accurately with the known biochemical markers indicative of Trisomy 18.