- ATHENS OFFICE MED4WOMAN ATHENS
- VOLOS OFFICE MED4WOMAN VOLOS
Obstetrician-Gynecologist
PhD, University of Athens Medical School
Obstetrician-gynecologist Panagiotis Polyzos practices at the Institute of Life, the IVF Unit of IASO Maternity Hospital.
Amniocentesis is an invasive prenatal test in which a small amount of the amniotic fluid surrounding the fetus is collected and the cells it contains are examined.
The cells in the amniotic fluid originate from the baby, and therefore, the chromosomes within these cells are the same as those of the baby.
Amniocentesis involves passing a fine needle into the uterus to remove a small volume of amniotic fluid. The path of the needle is monitored continuously with ultrasound.
Amniotic fluid is produced mainly by the fetus's urine, and the amount removed is replaced within a few hours.
The sampling takes about one minute, and afterward the doctor checks that the fetal heartbeat is normal.
For the first two days, you may experience some abdominal discomfort or period-like pain. It may be helpful to take simple pain relief such as paracetamol.
If you have a lot of pain, bleeding, fluid loss from the vagina or a fever, seek medical advice.
The results for Down syndrome and other major chromosomal abnormalities are usually available within 3 days. The results for rare abnormalities take 2 weeks. Once we receive the results, we will call you to inform you.
The risk of miscarriage caused by the test is small. It used to be estimated at around 1%, while more recent studies, when the test is performed by an experienced maternal-fetal medicine specialist, place it much lower, at 0.1 to 0.3%. It is similar to that of chorionic villus sampling (CVS). If a miscarriage does occur because of the test, it usually happens within the first few days.
Some studies have shown that when amniocentesis is performed before 16 weeks there is a small risk of clubfoot (a deformity of the foot) in the newborn. To avoid this risk, we never perform amniocentesis before 16 weeks.
Amniocentesis is not done for every pregnant woman. It is recommended when:
The decision always belongs to the parents, after detailed counseling. See the full range of tests in prenatal care.
The visit takes about half an hour in total, while the sampling itself takes only a few seconds. Knowing the order of the steps makes the wait much calmer.
Your partner can usually stay by your side. Ask to have each step explained as it happens, if that reassures you.
Amniotic fluid can be analyzed with different techniques, each with its own turnaround time and scope:
Most results are clear-cut: normal or clearly abnormal. There are, however, some in-between answers that are worth knowing about in advance. The array may detect a “variant of uncertain significance”, meaning a change that is not known to affect health. In this case a blood test from the parents is often requested to see whether either of them carries it. Rarely, mosaicism is found, when only some of the cells carry the change, or the cell culture fails. In both cases genetic counseling helps decide the next step.
Amniocentesis is a choice, not an obligation. The decision is personal and there is no right or wrong answer. A few questions help many couples clarify what they want:
For couples who are carriers of an inherited condition, the discussion also concerns future pregnancies. One alternative is preimplantation genetic testing (PGT) of embryos as part of IVF, so that testing takes place before the pregnancy begins.
In twin pregnancies the test requires more planning. The key question is whether the fetuses have separate placentas or share one, which is determined accurately on the first trimester ultrasound.
The risk of pregnancy loss is slightly higher than in a singleton pregnancy, which is why the test is done at centers experienced in multiple pregnancies. Many twin pregnancies result from in vitro fertilization, and if the embryos were tested before transfer, the need for invasive testing is discussed on an individual basis.
Most amniocenteses are performed between weeks 16 and 20. However, some indications lead to the test being done later:
After the fetus reaches viability, a rare complication may lead to preterm birth rather than miscarriage. This is discussed in detail before the test and determines where it will be done.
Some maternal conditions do not rule out amniocentesis, but they change how it is organized:
Tell your doctor about every medication and any chronic condition before booking the appointment.
For many couples, the days between the test and the answer are the hardest of the pregnancy. A few practical steps help:
For the vast majority of women the result is normal, even when screening had shown an increased risk. Ultrasound monitoring continues as usual, as described in our guide to obstetric ultrasound.
There are situations where it is safer to wait a few days or to reassess the indication:
Postponing by a few days does not affect the value of the result. On the contrary, it reduces the chance of a complication. If any of the above applies on the day of your appointment, let the office know before you set off for the test.
Most women describe a sting and some pressure for a few seconds, not severe pain.
From week 16 onward, usually between weeks 16 and 20.
Chorionic villus sampling is done earlier, at 11 to 14 weeks, and examines placental tissue. Amniocentesis is done from week 16 and examines cells from the amniotic fluid.
No. NIPT is a screening test with very high sensitivity, but a positive result is always confirmed with invasive testing.
A relaxed schedule is recommended for 24 to 48 hours. Bed rest is not needed.
Yes, chromosome analysis also shows the sex chromosomes. If you do not want to know yet, tell your doctor in advance so that it is not mentioned when the results are discussed.
It happens rarely. Usually the rapid QF PCR method has already given an answer for the most common trisomies. If a full analysis is needed, repeating the test or an alternative approach is discussed, depending on gestational age.
It is best to avoid long trips for the first 24 to 48 hours, so that you are close to your doctor if pain, fever or fluid leakage occurs. There is no evidence that flying is harmful; the restriction is a practical one.
No. A successful amniocentesis without complications changes nothing in planning the delivery. The type of delivery is determined by the course of the pregnancy and the fetal findings.
