Describe relative benefits and risks of non-invasive prenatal testing (NIPT), combined first trimester screening (cFTS), chorionic villus sampling and amniocentesis

- Non-invasive (no risk of miscarriage).

- Very accurate test for Down's and Edward's - less so for Patau's.

- Can test for foetal gender at a younger age.

Benefits of NIPT

- Expensive as is not covered by medicare.

- Is screening not diagnostic.

- May detect genetic conditions in the mother.

- May receive false positives (very low risk) but lots of stress.

- Positive result requires confirmation by invasive testing.

- Analysis is restricted to chromosomes 21, 18 and 13.

Risks/drawbacks of NIPT

- Diagnostic test.

- Sensitivity and specificity of >99.9%.

- Able to detect other abnormalities other than trisomy's (cystic fibrosis, sickle cell anaemia).

- Can be done earlier than amniocentesis.

- More time to consider results when compared to amniocentesis.

Benefits of CVS

- Risk of birth defects or miscarriage is 1-2% (this is because the test is carried out earlier than amniocentesis).

- Unable to measure AFP (can't detect neural tube defects).

- Infection from procedure (invasive).

- Risk of rhesus sensitisation (this is why mothers given anti-D after procedure).

- May have to undertake a second procedure if sample is too small.

Risks/drawbacks of CVS

- Diagnostic test.

- Sensitivity and specificity of >99.9%.

- Able to detect abnormalities other than trisomy's.

- Able to measure AFP (can detect neural tube defects).

- Can check for foetal lung maturity.

Benefits of amniocentesis

- Risk of miscarriage is 0.5-1%.

- Risk of infection and rhesus sensitisation (same as CVS).

- Risk of club foot.

- Longer wait for results than other testing.

- Woman may experience cramping, bleeding or leaking of amniotic fluid after procedure.

Risks/drawbacks of amniocentesis