Invasive procedures are procedures designed to obtain samples from the placenta (CVS), amniotic fluid (amniocentesis) and fetal blood (cordocentesis) for analysis.

Such procedures are offered when babies are thought to have an increased risk of having a chromosomal or genetic disorder such as sickle cell, cystic fibrosis or thalassaemia.

Sickle Cell Diseases

These are a group of inherited health conditions that affect the red blood cells.

It produces unusually shaped red blood cells which cannot live as long as healthy blood cells and can cause blockages in the blood vessels.

It is most common in people with an African or Caribbean background.

Thalassaemia

Thalassaemia describes for a group of conditions that can be inherited and affect a the haemoglobin in the blood.

As a result the body produces either too little or no haemoglobin, for carrying oxygen around the body causing anaemia

It predominantly affects people of Mediterranean, South Asian, Southeast Asian and Middle Eastern origin.

Cistic Fibrosis

Cystic fibrosis is another inherited condition that causes a build-up of mucus in the lungs and digestive system, causing infections on the lung and problems digesting food.

Carrier screening for CF is offered to all women planning to get pregnant or are already pregnant. Both partners must be carriers for a fetus to have CF.

INVASIVE

PRENATAL TESTING

At 11 to 14 weeks

With ultrasound guidance, a fine needle is inserted through the mother’s abdomen into the placenta and a small placental sample (chorionic villi) is collected for analysis.
Available after 15 weeks

With ultrasound guidance, a fine needle is inserted through the mother’s abdomen into the amniotic sac and a sample of amniotic fluid is collected and sent to the lab.
Available from 18 weeks

With ultrasound guidance, a needle is passed through the mother’s abdomen and a sample of the baby’s blood is taken from the cord.

In addition to the indications mentioned above, this test is important if the mother is in the rhesus negative blood group.