Amniocentesis: result in 48 hours

2000/09/01 Murua Uribe-Etxebarria, Aitziber Iturria: Elhuyar aldizkaria

• Medikuntza

Through high-resolution ultrasound, a direct follow-up of pregnancy is carried out, closely following the process from embryo to birth.

Amniocentesis is the technique used to determine if the child has chromosomal abnormalities at birth. Although this technique began to be used about seven years ago, in recent months specialists have launched in the Gynaecological Office of Polyclinic Gipuzkoa an advance they consider beneficial: To be able to know within two days the average result by amniocentesis on the chromosomal anomaly that causes down syndrome.

Therefore, through prenatal diagnosis, parents will be able to know that in the fourteenth week of pregnancy their child will not suffer any chromosomal abnormalities; on the contrary, if the results confirm that the baby to be born will suffer some abnormality, parents will be able to decide what to do before the pregnancy.

At the Gynaecological Office of Polyclinic Gipuzkoa, the doctor specialized in the aforementioned prenatal diagnostic techniques, Antonio Estonba, explains what the precise explanations and the latest advances in these techniques consist of.

Prenatal diagnosis

When we talk about prenatal diagnosis we talk about techniques to diagnose abnormalities in the fetus as soon as possible. Abnormalities that may occur in the fetus may have their origin in chromosomal or nonchromosomal malformation.

The latest diagnostic techniques are high-resolution ultrasound and amniocentesis. Currently, high-resolution ultrasound is the most widely used technique for the diagnosis of pregnant women. Amniocentesis is spreading, according to specialist Antonio Estonba of the Gynaecological Office of Polyclinic Gipuzkoa. For safety reasons, more and more women are asking for amniocentesis. Currently, 30% of pregnancies that are treated use amniocentesis.

Therefore, the technique called amniocentesis is used to diagnose chromosomal abnormalities or chromosomal calls in medicine. Chromosomal abnormalities, according to approximate general data, occur in one in 200 children born. In fact, most fetuses with chromosomal abnormalities appear to die in the first months of pregnancy. As a result, very few people arrive well at the end of pregnancy. Some of these abnormalities may be inherited. However, most of them are accidental.

The most known and widespread chromosomal abnormality is Down syndrome. In addition to Down syndrome produced by chromosome 21, there are many other chromosomal abnormalities. In some women, the risk of having children with chromosomal abnormalities increases. Among other things, when the pregnant woman is over 35 years old or has had a fetus with chromosomal abnormalities.

On the other hand, the most advanced technique to diagnose non-chromosomal malformations such as the bifid spine, etc. is high-resolution ultrasound.

High-resolution ultrasound

Currently, in all pregnancies treated at the Gynaecological Office of Polyclinic Gipuzkoa, high-resolution ultrasound is an essential technique for prenatal diagnosis. Ultrasound, which has made it a basic resource for prenatal diagnoses, is the precise and useful information obtained from it and that, in addition, the absence of risk for pregnancy is guaranteed, making it even more reliable.

In a context in which the use of a high-resolution ultrasound in the field of gynecology is widespread, according to the doctor specializing in gynecology, Antonio Estonba, high-level ultrasound must meet three basic requirements:

• Ultrasound should be performed by an ultrasound specialist and not by a gynecological specialist.
• To achieve a high-level ultrasound it is necessary to perform with a good technical team.
• Devote enough time to performing ultrasound. Rapid ultrasound may result in the loss of information needed for diagnosis.

Through high-resolution ultrasound, a direct follow-up of pregnancy is performed, closely following the process from the embryo to the baby's formation. The goal is to make an accurate and rapid diagnosis of abnormalities. As a result, five upper ultrasound scans are performed in normal pregnancies: Weeks 8, 14, 20, 32 and 36.

Ultrasound provides detailed information about the fetus. During the first three months you can tell if the fetus is alive, how many fetuses there are and the belly age. From the third month it will be possible to know if the fetus has any congenital structural disease, the situation of the placenta and the existence of sufficient fluids. Most of the time, fetal sex is known from the second trimester.

Amniocentesis

As already mentioned, high-resolution ultrasound is an advanced technique used in all cases for prenatal diagnosis, while amniocentesis is a complementary technique of the same diagnosis. However, according to Dr. Antonio Estonba, more and more women want to use this technique, driven by security. In fact, 30% of pregnancies treated in the Gynecological Office are diagnosed by amniocentesis. According to the doctor Antonio Estonba, currently performing this test with the appropriate techniques and with specialists, poses a virtually zero risk for pregnancy, while from it you get preferential information for parents.

Amniocentesis is a laboratory study of amniotic fluid from the breast bag. It confirms the existence or not of chromosomal abnormalities in the fetus. This is done in the week 14-15 of pregnancy, and the topic of this period is based on two reasons: on the one hand, because before those weeks have not formed the cells of the fetus; on the other, because if some abnormality is confirmed in the fetus and the parents so decide, by law the interruption of the pregnancy is only authorized until week 20.

More and more women are using amniocentesis. This test is always done at the request of the couple and following their will. However, the doctor Antonio Estonba has informed us that there are women who have a higher risk of fetus with a chromosomal anomaly: on the one hand, when the pregnant woman is over 35 years old, since from that age the risk of having children with chromosomal abnormalities is higher (see table). On the other hand, in cases of fetus with previous chromosomal abnormalities. In these cases the specialists consider it totally convenient to carry out the amniocentesis, since in many cases the results obtained through it will be decisive for the parents.

Although amniocentesis began to be used about seven years ago, at the Gynaecological Office of Polyclinic Gipuzkoa, what is considered as a step forward has been achieved: knowing in 48 hours the result of Down syndrome, the most widespread chromosomal anomaly. In fact, although we have to wait between 15 and 20 days to obtain the total result of this study carried out in the laboratory, in recent months we have managed to know the result of chromosome 21 that generates Down syndrome within two days.

With this last breakthrough they have launched, they have managed to greatly shorten 48 hours the period of nervousness that until a few months ago extended to twenty days for parents.