What are the alternatives to chorionic villus sampling?

Chorionic villus sampling tests placental tissue. Amniocentesis tests a sample of amniotic fluid, so it is performed at a different stage of pregnancy and uses a different source of genetic material. Both are diagnostic procedures, but neither answers every possible pregnancy question.

Non-invasive screening uses blood and ultrasound information to estimate the chance of selected chromosome conditions, including Down syndrome. Screening can guide decisions about diagnostic testing, but it does not provide the same type of confirmation as a diagnostic sample.

A fetal medicine or genetics team can compare the reason for testing, timing, possible findings, and how results might affect your decisions. Tell them whether you want information about a specific inherited condition, a chromosome condition, or fetal anatomy. The choice also depends on gestational age and your previous screening results.

After an invasive pregnancy test, contact your maternity unit for heavy bleeding, fluid leakage, fever, worsening abdominal pain, or contractions. Before testing, seek prompt advice if you have new bleeding or pain so the team can decide whether assessment should happen first.

Ask what the test is designed to detect, when results are expected, whether the result is screening or diagnostic, and what choices would follow each possible result.