Question

What patients should be offered invasive prenatal genetic screening?

a) All pregnant patients
b) Patients with a history of multiple pregnancies
c) Patients over 35 years old
d) Patients with a history of gestational diabetes

Answer 1

Invasive prenatal genetic screening should be offered to patients over 35 years old (c).

Step-by-step explanation:

The decision to offer invasive prenatal genetic screening is often based on the assessment of maternal age, as advanced maternal age is associated with an increased risk of chromosomal abnormalities such as Down syndrome. The age of 35 is a commonly used threshold in clinical practice. This threshold is chosen because the risk of chromosomal abnormalities, especially Down syndrome, tends to rise significantly after this age.

The rationale behind this lies in the increased likelihood of chromosomal nondisjunction events during meiosis in older women. For instance, the risk of having a baby with Down syndrome at age 35 is about 1 in 200, while at age 40, it increases to approximately 1 in 100. The trend continues to escalate with advancing maternal age.

While other factors, such as a history of multiple pregnancies or gestational diabetes, may influence the decision to offer certain types of prenatal screening, invasive procedures like amniocentesis or chorionic villus sampling are generally recommended for patients over 35 due to the higher baseline risk. It's important to consider individual patient circumstances and preferences in making these decisions, but age remains a critical factor in determining the appropriateness of invasive prenatal genetic screening.