Prenatal genetic counseling may help with the decision-making process by walking patients through examples of what some people might do in similar situations, and their rationale for choosing that option. Decisions made by patients are affected by factors including timing, accuracy of information provided by tests, and risk and benefits of the tests. This discussion enables patients to place the information and circumstances into the context of their own lives, and in the context of their own values. They may choose to undergo noninvasive screening (e.g. ultrasound, triple screen, cell-free fetal DNA screening) or invasive diagnostic testing (amniocentesis or chorionic villus sampling). Invasive diagnostic tests possess a small risk of miscarriage (1–2%) but provide more definitive results. Testing is offered to provide a definitive answer regarding the presence of a certain genetic condition or chromosomal abnormality.