What is the procedure called that involves taking a fluid sample between the 15th and 16th week of pregnancy to diagnose congenital anomalies?

The procedure described for taking a fluid sample between the 15th and 16th week of pregnancy to diagnose congenital anomalies is known as amniocentesis. This technique involves inserting a thin needle through the abdominal wall into the amniotic sac to collect a small amount of amniotic fluid, which contains fetal cells and various substances that can be analyzed for genetic conditions and structural anomalies.

Amniocentesis is typically performed during the second trimester, allowing for early detection of conditions such as Down syndrome and certain fetal infections. The timing is crucial, as it is most commonly performed between weeks 15 and 20 of gestation.

Other procedures are mentioned, such as chorionic villus sampling, which is done earlier in the pregnancy (usually between weeks 10 and 13) and involves taking samples of placental tissue for testing. Ultrasound imaging is a non-invasive procedure used to visualize the fetus and assess various aspects of its development but does not involve fluid sampling. Fetal biopsy is a more complex procedure that is not routine and typically involves sampling tissue from the fetus rather than amniotic fluid.