Amniocentesis also referred to as amniotic fluid test or ATF is a medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections. It is also used for sex determination in which a small amount of amniotic fluid, which contains fetal tissues, is sampled from the surrounding amniotic sac. The fluid contains live fetal cells and other substances such as alpha-fetoprotein (AFP). These substances provide important information about your baby’s health before birth.
Amniotic fluid (less than one ounce) is removed through a fine needle inserted into the uterus through the abdomen, under ultrasound guidance. The fluid is then sent to a laboratory for analysis. Different tests can be performed on a sample of amniotic fluid, depending on the genetic risk and indication for the test.
Why Amniocentesis is performed
Amniocentesis is usually carried out from 15 weeks of pregnancy onward and is NOT a routine test. Your obstetrician will only recommend an amniocentesis if there’s a higher than normal chance your baby may have a particular condition. The test can also reveal whether you’re having a boy or a girl. So if you’d rather not know, tell your obstetrician before the test is performed.
A complete anatomical ultrasound will be done prior to amniocentesis. But amniocentesis is performed to look for certain types of birth defects.
Whether you have the test or not is your choice. Your midwife or obstetrician can talk you through the pros and cons, and will support your decision
What are the pros and cons?
The amniocentesis can be used in early pregnancy to detect genetic defects in the foetus due to chromosomal abnormalities (like Down syndrome), sex-linked defects , neural tube defects (like spina bifida), inborn errors of metabolism (like cystic fibrosis), and enzyme deficiencies (like Tay-Sachs disease).
Indications for genetic amniocentesis include advanced maternal age, previous child born with a chromosomal abnormality, parent carrying a chromosomal abnormality, and family history of neural tube defects.
- Complications are rare but some can be serious.
- The placenta, foetus, or umbilical cord may be punctured inadvertently, causing injuries ranging from minor scratches of fetal parts to intrauterine haemorrhage, leading to fetal distress and intrauterine fetal death.
- Placental perforation could result in haemorrhage from the fetal circulation, which could lead to fetal anaemia or to increased sensitization of an Rh negative mother.
- Other hazards include induction of preterm labor and intra-amniotic infection.