Which of the following findings would be considered abnormal in a patient's Down's quadruple screen?

In the context of Down syndrome screening during pregnancy, the quadruple screen measures various markers in maternal serum to assess the risk of chromosomal abnormalities in the fetus. The expected findings in a Down syndrome pregnancy typically include:

1. High levels of HCG (human chorionic gonadotropin).

2. Low levels of AFP (alpha-fetoprotein).

3. Low levels of estriol (one of the estrogenic hormones).

4. Low levels of inhibin A.

Considering these expected results, an abnormal finding in the quadruple screen for a pregnancy at increased risk for Down syndrome would indeed be high HCG. Therefore, a situation where HCG is high alongside low estriol indicates a heightened risk for Down syndrome.

In the provided alternatives, the combination of high HCG and low estriol is consistent with the typical abnormal profile seen in pregnancies with a higher risk of Down syndrome. This contrasts with other combinations where either the markers are normal or exhibit deviations that would not typically suggest Down syndrome.