What is a multiple marker screening?

Genetic Screen. A multiple marker screen uses measurements of four analytes (bhcg, estriol, afp, and inhibin-a) to determine the likelihood that a fetus has down syndrome, t16, or t13 (more severe anomalies than downs). It also screens for neural tube defects, but ultrasound has replaced this screen as a superior modality. Importantly, the test does _not_ tell you if the baby had downs, it only quantifies risk.
Multiple marker. If related to pregnancy, it would be to assess the mother's risk of having a child with genetic diseases such as trisomy 18 and 21, etc.