Amniocentesis is an invasive prenatal diagnostic technique by which a small amount of amniotic fluid is removed from the gestational sac, with which it is possible to perform certain studies.
It is performed through the abdomen of the mother, without need for anesthesia, through a fine needle and under ultrasound control (in this way the fetus is always visualized and its puncture is avoided). The surface of the maternal skin has been previously disinfected to prevent germs from crawling. The amniotic sac is pinched, away from the fetus, and once the needle is located, the amniotic fluid is drawn through a syringe. The extracted liquid is regenerated in a few hours.
Rest and care after amniocentesis
For amniocentesis no special preparation is necessary. It is performed on an outpatient basis after 14 weeks of gestation and the patient can return to her home immediately without problems. He is warned that in the next few hours he may have pelvic discomfort that does not matter.
In our center, the recommendations to the pregnant woman after an amniocentesis are:
- Home rest for 24 hours (no bedding is necessary but stay as long as possible at rest, eg. sofa, although you can get up to eat, serve, or climb a few stairs)
- After that 3-4 days of relative rest is recommended, that is to say, their habitual life with the greater possible rest that includes not doing abdominal efforts, not to give great walks, to avoid the sport and to avoid sexual relations. We also recommend avoiding immersion baths (bath or pool), but it is surely a recommendation that has no scientific basis.
As the only alarm to go to the clinic we notice bleeding or a loss of vaginal fluid.
If the woman is Rh negative, with a Rh-positive father, anti-D Gammaglobulin is given to the mother to avoid possible immunization if the fetus is Rh positive (the latter situation we can not know).
Indications or situations that would make it advisable, or not, to practice it
There are some indications that we will call "classic", which are related to certain risk factors: antecedent of a child with chromosomal abnormality , that one of the progenitors be carrying some chromosomal abnormality, repetitive abortions or a history of unexplained fetal death, has detected an anatomical abnormality in the fetus that makes it suspect that it may be a carrier of chromosomopathy and, the better known, advanced maternal age .
At higher maternal age is the risk of chromosomal abnormality , mainly trisomies, such as Down's Syndrome, because there are other chromosomal abnormalities that are not related to age.
But nowadays there is an indication that has grown significantly: the desire of the parents, for their concern (badly called anxiety) about whether the fetus is healthy.
The number of pregnant women who "a priori" could undergo an amniocentesis has increased in the last 20 years, mainly due to the increased age of the pregnant woman.
But there are also other reasons: fewer children, first child at later age (the mean is more than 32 years old), more gestations obtained after reproduction techniques.
It is also true that new non-invasive prenatal diagnostic methods have emerged in maternal blood , especially those related to Down syndrome (trisomy 21), which could reduce the number of amniocentesis, but at the cost of not detecting other anomalies .
This percentage can vary widely according to the centers, their protocol of prenatal diagnosis offer, which population of pregnant women at risk ... It is difficult to find absolute contraindications for amniocentesis, although there are situations that will have to assess the risk / benefit ratio of its realization: presence of uterine fibroids, mother carrying diseases with possible contagion to the fetus ...
Risks of amniocentesis
The fundamental risk is that of abortion after the test. Classically there has been talk of a one percent risk, clearly exaggerated at present, with higher resolution ultrasound and more qualified personnel.
In centers with experience, there is a 0.1 and 0.3 percent risk of abortion related to amniocentesis.