When is the test done;
Amniocentesis is performed after the 15th gestational week.
Why is amniocentesis needed?
The commonest indications are:
- Increased risk for a chromosomal abnormality as calculated by the combined test (the combination of maternal age, ultrasound and biochemical markers) in the first trimester or chromosomal markers in the anomaly scan.
- History of a genetic disease in the family.
- Discovery, after ultrasound, of a congenital abnormality in the fetus.
- Fetal metabolic disease investigation.
- Assessment of fetal lung maturity.
- Decompression of the uterus in cases of particularly increased amniotic fluid (polyhydramnios)
- Maternal wish.
Amniocentesis is a diagnostic test. It is done by collecting a very small amount of amniotic fluid (approximately 15- 20 ml) from the pregnancy sac. The cells found in the amniotic fluid come from the fetus, therefore the chromosomes found in these cells are the same as the ones found in the baby.
How is the test done?
First, we clean the tummy’s skin with anteseptic. As the needle used in the procedure is thinner than the local anesthetic needle, no local anesthetic is needed. Subsequently, this very fine needle passes through the tummy, into the amniotic sac, does not touch the baby at any moment and a small amount of amniotic fluid is aspirated. The whole procedure lasts for about 1- 2 minutes and at the end of the procedure the fetal heartbeat is checked. The following video demonstrates the procedure’s technique.
What happens after amniocentesis is done?
After we confirm that the fetal heartbeat is normal, the miscarriage risk decreases significantly. For the next 2- 3 days you might experience some symptoms like mild abdominal ache, period- like cramping and mild vaginal bleeding. These are quite common after amniocentesis and you should not be really worried since, in most of the cases, pregnancy continues normally. In case you want to ease any symptoms, you can take simple painkillers like paracetamol either orally or as suppositories. In case you feel intense pain, experience heavy bleeding, have watery vaginal discharge or have fever, you need to contact us immediately or visit a hospital.
Amniotic fluid is comprised (in 99%) by the baby’s urine, so the amount of fluid that was removed is replaced within hours.
When are the results back?
The results are announced in two ways. The first results for Down’s syndrome or other major chromosomal abnormalities come from PCR and are back in 2- 3 working days. In 99% of the cases, they are identical to the final ones. These results (the final ones) come from cell cultures and for the major chromosomal abnormalities are back in 2 weeks. Whenever we have the results, we will let you know immediately.
Does the procedure need to be repeated for any reason?
In about 1% of the cases, the test needs to be repeated because the results will be inconclusive. amniocentesis.
Are there any risks from amniocentesis?
Luckily, the procedure- related risks are uncommon. There is a 1 in 100 chance of miscarriage caused by the test. This risk is the same as the one from CVS at 11- 15 weeks. If you were about to miscarry because of the procedure, this will happen in the next, few days. The risk goes down by 85% after the first 24 hours.
There is a 1 in 1000 chance of maternal infection. This is why we will disinfect the area with antiseptic and use, practically, sterile methods of performing the procedure.