Amniocentesis examines your unborn baby's new life long before its birth. The contents of amniotic fluid include cells from the baby's skin and other organs which can be used to diagnose the baby's condition should the need arise. Amniocentesis or amnio as it is popularly known is an invasive procedure and it basically entails amniotic fluid to be withdrawn from the uterus.
Why do you need an Amnio?
- If you are over 35, the risk of having a baby with Down's syndrome increases
- If the father is over 50 this procedure may be advised
- You have had a screen positive result from an earlier antenatal test and want some definite results
- You had a previous baby with a genetic disorder
- You have a family history of Down's
The need for an amnio also arises if there is an increased risk of:
- Rhesus factor problems
- Congenital absence of the brain (anencephaly)
- Respiratory distress syndrome
- Congenital defects in the spinal cord and column (spina bifida)
- Cystic fibrosis
- Hemophilia
- Duchene's muscular dystrophy
- Thalassaemia
- Sickle-cell anemia
- Antitrypsin deficiency
- Phenylketonuria
The Risk factor
The main risk is miscarriage. Hospitals that do frequent amnio have lower rates of miscarriages. An interesting fact to consider is: if you have been advised to have an amnio because of a raised AFP level, be advised that there appears to be a link to a significant increase in miscarriage rates; this is apparently so because babies with raised AFP have a problem and would have miscarried at some later stage anyway. If this applies to you, you should be offered a detailed ultrasound rather than an amnio for the diagnosis of NTD.
The Procedure itself..
Amnio is often carried out between weeks 16 and 20 by an experienced, well trained Operator. The reason to wait till this long is because there will be more amniotic fluid present and the likelihood of needle puncture on the fetus, the placenta or umbilical cord is very low. Secondly and more importantly, the presence of fetal cells in the sac will be higher, increasing the accuracy of the test.
- You will have to empty your bladder
- Antiseptic will be used to clean your skin
- A needle will be passed into your uterus through the abdominal wall, and a sample of fluid is drawn up.
- This is done under direct ultrasound control so no harm is done to the fetus or placenta
- It takes about 10-15 minutes
- It is usually more uncomfortable then painful
- This sample is immediately sent to the lab for evaluation; fetal cells are separated from the liquid to be cultured for chromosomal analysis
What the test reveals:
- The age of the fetus
- The genetic disorders
- The metabolic problems and other birth defects
What happens after the test?
- Your doctor will check your baby's heartbeat to ensure all is well
- If you are rhesus negative you will be administered with an Anti-D injection
- You should go home and rest for 24 hours minimum
- If there is bleeding or fluid leakage, call your doctor immediately
- You will need to wait for 2-3 weeks for the results as by that time the cells would have grown or cultured enough for an analysis
- You can choose to continue with the pregnancy and keep the baby or opt for a termination; the choice is yours. ( Termination laws depends on country to country, so please check with your doctor)
The down side of amnio
Apart from the miscarriage factor, the other worse thing is the timing; you may be forced to face with one of life's most crucial decision after such a wait. By the time the results are back you may be close to being 20 weeks pregnant. Not only have you grown more emotionally attached to your unborn child, but second trimester terminations are more difficult to perform and are more complicated.
When faced with an amnio?
- Discuss all your options and concerns with your doctor before you make the appointment for the test
- Prepare ahead with your partner on all possibilities and weigh the odds, wherever necessary.
Related Article of Amniocentesis - the merits and demerits