If your first trimester combined screening, second trimester serum screening, or non-invasive prenatal testing comes back with an increased chance of chromosomal anomalies, you will be offered a referral to the obstetric team at Te Rauru Antenatal Clinic. They will go over the options with you, which may include Non-Invasive Prenatal Testing (if you have not had this already), chorionic villus sampling, or amniocentesis
Chorionic Villus Sampling
This involves using an ultrasound-guided needle either through your abdomen or through your vagina, depending on the location of your placenta, to take a sample of the developing placenta. The sample will be analysed for chromosomal anomalies, including X-linked disorders. It can tell you the sex of your baby, but the obstetric team do not have to tell you this if you do not want to know. The test takes 10-14 days to come back.
It is usually carried out in the first trimester, and carries a slightly increased risk of miscarriage, about 0.2% more than if you did not have the test.
Other risks include infection, haemorrhage, cervical damage, and ambiguous results. If there are ambiguous results, you will be offered further testing.
If you are Rhesus negative, you will be offered Anti-D at the time of the test.
Amniocentesis
This involves using an ultrasound-guided needle to go through your abdomen and into your uterus, which then takes a small sample (10-15mL) of amniotic fluid from around the baby. Ultrasound is used to avoid touching the baby or the placenta. The baby’s cells found in the amniotic fluid are checked for chromosomal anomalies, while the fluid is checked for raised levels of substances that can indicate neural tube defects. The test takes 2-3 weeks to come back.
It is usually carried out between 15-18 weeks gestation, and carries a slightly increased risk of miscarriage, about 0.1% more than if you did not have the test.
Other risks include damage to baby, cord or placenta, infection, amniotic fluid leakage or rupture of membranes.
If you are Rhesus negative, you will be offered Anti-D at the time of the test.