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Prenatal studies give more information about the baby than ever

11.11.2019

Not a long time ago, just 30 years, a gynaecologist tried to find out whether a woman was pregnant and in case of pregnancy, estimate the approximate size of the pregnancy by internal examination. At the same time, it was not possible to be sure whether the fetus is alive and from time to time, mistakes were made in diagnosing the twin pregnancy.  Also, the discovery of the ectopic pregnancy was all too often late. Currently, it is possible to detect pregnancy using the ultrasonography with the vaginal probe already when only two weeks have passed from the missed period.

 

It is now common that a woman does the pregnancy test two days after the missed period and if it is positive, and there are no complaints comes to the doctor’s appointment in two or three weeks. In the early pregnancy phase, the gynecologist or a midwife detects by the means of vaginal ultrasonography whether it is an intrauterine or an ectopic pregnancy. Also the size, viability, existence of multiple pregnancy and its type (whether there is a single or several developing placentas) are specified.

 

If the ectopic pregnancy or Cesarean scar pregnancy is detected, it is possible to help the woman in an early stage and it is often possible to preserve the uterus and fallopian tube.

 

The timely detection of multiple pregnancy is very important as then the risk for premature childbirth, birth defects and growth retardation of the fetus is higher. In case of twins who share one placenta (monochorionic twins), there is also a risk of transfer of transfusion syndrome from one fetus to another. That’s why the twin pregnancy is monitored more frequently and with special care. The existence of triplets has even bigger risks to the life and health of the expecting mother and fetuses and so it is possible to reduce one of the triplets before delivery.  The earlier the procedure is performed, the bigger is the chance that the pregnancy proceeds without problems.

 

The next prenatal study is the ultrasonography of the I trimester with the initial aim to detect the fetuses with Down syndrome. As now the gynecologists have the precise screening tests for assessing the extracellular DNA from the fetal venous blood, the importance of the ultrasonography for detecting the Down syndrome during the I trimester has decreased, and instead, the importance of assessment of the earlier organ structures has increased.

 

 

The screening of the fetal birth defects moves to the I trimester

 

In connection with commissioning of new ultrasound apparatuses and increase in experience of the physicians, the screening of the fetal birth defects more and more move to the 1. trimester. The high resolution ultrasound sensors help to assess the heart and brain structures of the fetus with the size of ta thumb and detect already half of the difficult birth defects unsuited for life. In case of serious birth defects, the woman can terminate the pregnancy, if desired, already before she feels the movements of the child. This is important, because the smaller the fetus is at termination of pregnancy, the smaller are the accompanying risks to the health and life of the mother and at the same time the bigger are the chances to get pregnant in the future. 

 

 

In case of an anomaly of the fetus, it is possible to provide the woman the chorionic biopsy for obtaining final diagnosis during which it is possible to examine the fetal karyotype (chromosomes) as well as perform submicroscopic analysis and exome sequencing for timely detection of rare gene diseases. It has been approved that after the chorionic biopsy, the risk of termination of pregnancy is very low - just 0.1%. Hence this study is irreplaceable for obtaining the final diagnosis.

 

During the I trimester, the ultrasonography  helps to assess the risk of pregnancy time complication preeclampsia (disease that is characterized by the growth retardation of the baby, compromised kidney and liver function of mother, increased blood pressure and in more difficult cases, occurrence of the cramp-fasciculation syndrome that is fatal for the mother and the fetus). For the high risk of preeclampsia, administration of a low-dose aspirin (150mg every evening before going to bed until 36th pregnancy week) may prevent onset of the disease or shift it to the later period when the baby themselves starts to breath at birth.

 

 

The most important pregnancy ultrasonography is the screening of the fetal birth defect on the 20th pregnancy week

 

During that ultrasonography, it is assessed whether the fetal abdomen, spine and the brain case are intact. More attention is paid to the brain and heart structures and the functions of the baby. Baby’s movements and whether its kidneys are functioning, whether the urinary bladder is filled and if there is enough amniotic fluid and whether the baby swallows.

 

3D/4D ultrasound apparatus allows to examine the not yet born child in 3D. The resolution and penetration of the ultrasound apparatus is very important. This enables to get  a good overview of smaller details. This is specially important for the sessment of the brain structures.

 

During the last years, the assessment of fetal brain structures have made significant progress. As gynecologists, we are able to assess the structures on which the mental and psychomotor development of the children depends.  The MRI or the magnetic resonance image that up to now has been primarily used for extracorporeal studies but now more and more, it is used for specifying the diagnosis of pre-delivery development failures.

 

 

It is possible to re-assess the risk of preeclampsia for the patients who had an elevated risk of onset of preeclampsia during the I trimester combined screening to find out whether the current aspirin prophylaxis has been efficient.

 

Beside screening the baby, attention is also paid to the pathology of the placenta and the cervix. If needed, it is possible to calculate the risk of the preterm delivery by measuring the length of the cervix and assessing its texture by the means of the vaginal ultrasonography. In case of an elevated risk, it is possible to extend the length of pregnancy until the child is viable with the support sutures to the cervix or by starting the vaginal progesterone treatment.

 

During the III trimester ultrasonography, an expecting mother gets an assurance for childbirth

 

III trimester ultrasonography is performed on the 34-36 pregnancy week. This aims at assessment of whether the fetus is in a head-down position or in breech presentation. If the fetus is in breech presentation, the gynecologist may turn the fetus into the head-down position on consent of the family. This procedure is successful during half of the cases and so it is possible to reduce the need for the C-section.

 

The growth of the fetus is assessed during the III trimester ultrasonography – whether the baby has achieved their growth potential. If only the midwife is measuring the abdomen, unfortunately the retarded babies are not detected in half of the cases. At the same time the children with retardation are the ones who might not feel well upon delivery and the need for an extraordinary C-section is increased.

 

During that ultrasonography, it is possible to assess the opportunity of the preeclampsia occurring after the 37th pregnancy week by measuring the blood pressure, determining the blood flow of the uterine arteries and the growth factor of the placenta. Detection of the late preeclampsia gives the gynecologist important information for safe monitoring of the mother before delivery.

 

The ultrasound apparatus enables to perform the Doppler ultrasound for the belly baby’s vessels and based on that it is possible to make conclusions about the well-being condition. The Fetal Ultrasound Screening Center has the ultra sound apparatus connected with a special software that also allows to assess the maturity of lungs. This is important in a situation where a small baby with the growth retardation who has not achieved their growth potential has to be delivered prematurely. Based on the maturity of the lungs of the fetus, it is possible to assess when is the best possible time for the baby to be born and whether it is necessary to perform preparation of the kid’s lungs with the adrenal gland hormone Dexamethasone.

 

Different genetic diseases can be detected during the pregnancy

 

An expecting mother can have four prenatal  different chromosome and gene disease tests in the Fetal Ultrasound Screening Centre. These screening tests are based on the extracellular DNA examination from the mother’s venous blood.

 

 Panorama test helps to examine that the fetus in the womb does not have Down, Edwards or Patau syndrome, X-linked diseases (Klinefelter and Turner syndrome) or triploidy.

 

In addition to the chromosome diseases above, Panorama XP test gives information also about the 5 most frequent genetic diseases that cause mental disability.

 

The aim of the Vistara test is to obtain knowledge about the pathology of 30 single genes of the fetus that cause 25 gene diseases not often detected during the ultrasonography and occurring only during the first years of life.

 

Horizon test investigates the parents against the 274 dominant autosomal diseases. If both parents carry the specified defective gene, there is a risk that their baby is sick in 25% of cases.

 

After the positive screening tests, it is necessary to perform the invasive diagnostic test (chorionic biopsy or an amniotic fluid study).

 

Majority pregnancies run without any problems. The prenatal ultrasound screenings and gene tests give the parents the feeling of certainty during this long time of expecting that the health of the belly baby is checked and kept.

 

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