If your quadmarker test results at 19 weeks show a low risk and low HCG level, it generally indicates that there is a lower likelihood of certain chromosomal abnormalities or birth defects. The quadmarker test measures the levels of four substances in the mother's blood - alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG), estriol, and inhibin-A. A low risk result means that the levels of these substances fall within the normal range for your stage of pregnancy. Additionally, a low HCG level may suggest a decreased chance of Down syndrome or other genetic disorders. However, it's important to note that this test is not diagnostic and only provides an estimate of risk. If you have any concerns or questions about your specific situation, it's best to consult with your healthcare provider who can provide personalized guidance based on your individual circumstances.