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Contents 6
Invasive Tests During Pregnancy
A Comprehensive Guide
Invasive tests during pregnancy are medical procedures performed using samples taken from the expectant mother's uterus or the fetus to assess the fetus's genetic and structural health. These tests are generally recommended when certain risk factors are present and are critically important for detecting possible abnormalities that could affect the baby's health. Invasive tests used during pregnancy include methods such as amniocentesis, chorionic villus sampling (CVS), and cordocentesis (fetal blood sampling).
Performing invasive tests can, in certain situations, be critical for protecting the course of the pregnancy and the health of the fetus. The main reasons that determine the need for these tests are as follows:
Why Invasive Tests Are Needed
Advanced Maternal Age: The risk of chromosomal abnormalities increases in pregnancies at age 35 and older. In this age group, the likelihood of trisomy conditions such as Down syndrome is particularly higher.
High Risk on Screening Tests: A high-risk result on the double, triple, or quadruple screening tests may require invasive testing. These tests can indicate a risk of a genetic disorder in the fetus and suggest that invasive testing is needed for a definitive diagnosis.
History of a Baby with an Abnormality: For mothers who have previously given birth to a baby with an abnormality, invasive tests are performed to determine whether a similar condition is present in the current pregnancy.
Family History of Genetic Disease: When there is a known genetic disease in the family, invasive tests may be performed to determine whether the fetus carries the condition.
Consanguineous Marriage: Marriages between blood relatives increase the risk of genetic disorders occurring. Children born from such marriages carry a higher risk of genetic disease.
History of Neural Tube Defect: Having previously had a baby with a neural tube defect increases the risk of a similar condition occurring in the current pregnancy, and invasive tests may be performed for early diagnosis of this condition.
Recurrent Pregnancy Loss: For mothers who have experienced multiple pregnancy losses, invasive tests may be performed to determine the cause of these losses and to help safeguard the current pregnancy.
Abnormality Detected on Ultrasound: When a structural abnormality is detected in the fetus on ultrasound, invasive tests may be required to confirm this finding and determine its cause.
X-Linked Diseases: When sex-linked genetic diseases are present, invasive tests are performed to detect these conditions, particularly in male babies.
Congenital Infection: Certain infections that develop in the womb can seriously affect the health of the fetus. Invasive tests may be used to diagnose these infections.
Amniocentesis (AC)
Important points about amniocentesis:
Amniocentesis is a prenatal diagnostic method performed between weeks 16-19 of pregnancy. In this procedure, samples taken from the amniotic fluid are used to analyze the fetus's genetic makeup. Amniocentesis is used particularly to detect chromosomal abnormalities and neural tube defects. It is performed by taking a sample of amniotic fluid, which contains cells carrying the genetic information of the developing fetus. By examining these cells, information about the fetus's chromosomal structure and genetic health can be obtained.
Preparation Before the Procedure: Before amniocentesis begins, an ultrasound examination is used to determine the fetus's position, the location of the placenta, and the amount of amniotic fluid. This assessment is critical for ensuring the procedure is performed safely and accurately.
Risks During the Procedure: One of the main challenges during the procedure can be tenting of the amniotic membrane by the needle after entering through the uterine muscle. This can make it difficult to draw fluid. If tenting occurs, the procedure may be stopped and attempted again a few weeks later. The risk of the needle contacting the fetus during the procedure is very low, and such contact is generally considered harmless.
Risk of Infection: The risk of infection after amniocentesis is extremely low, but infection can develop if bacteria from the mother's skin enter the amniotic fluid during the procedure. If signs of infection (pain, fever, foul-smelling discharge) are noticed, a doctor should be consulted immediately. In serious infections, termination of the pregnancy may become necessary.
Risk of Pregnancy Loss: The risk of pregnancy loss related to amniocentesis is approximately 0.5-1%. This risk can arise from fluid leakage, infection, or bleeding that may occur after the amniotic membrane is punctured by the needle. However, it is important to remember that a natural background rate of miscarriage also exists during this period, even in pregnancies where no procedure is performed.
Follow-Up After the Procedure: Hospitalization is generally not required after amniocentesis, but the expectant mother is advised to rest for 2-3 days. Strenuous physical activity and sexual intercourse should be avoided during this time.
Chorionic Villus Sampling (CVS)
Important points about CVS:
Chorionic Villus Sampling (CVS) is an invasive test performed between weeks 11-14 of pregnancy. This test uses samples of chorionic villus tissue taken from the placenta to analyze the fetus's chromosomal makeup. CVS offers an important advantage in providing early diagnosis of genetic diseases. This test is particularly preferred in situations where there is a high risk of a genetic disorder in the fetus.
Advantage of Early Diagnosis: Because CVS can be performed early in pregnancy, it provides a fast diagnosis. This allows the family to make decisions about the course of the pregnancy at an earlier stage.
Risk of Pregnancy Loss: The risk of pregnancy loss after CVS is approximately 1%. This risk is associated with bleeding and infections that may occur during the procedure. However, the natural rate of miscarriage that occurs at these weeks of pregnancy, due to natural selection, should also be taken into account.
Risk of Infection: The risk of developing an infection after CVS is very low. However, if an infection does develop, termination of the pregnancy is generally required. Any hematomas that may form in the expectant mother's body after the procedure usually heal on their own and do not require treatment.
Follow-Up After the Procedure: After CVS, the expectant mother is advised to rest for 1-2 days and avoid strenuous activity. Mild bleeding or pain may occur after the procedure, in which case paracetamol may be used.
Cordocentesis
Important points about cordocentesis
Cordocentesis is a test performed from the 16th week of pregnancy onward. In this procedure, a blood sample is taken from the fetus's umbilical cord to assess the fetus's genetic condition, blood disorders, and infections. Cordocentesis is particularly preferred when a rapid result is needed or for diagnosing blood disorders in the fetus. It is also used to assess fetal anemia in cases of blood incompatibility and, when necessary, to perform a blood transfusion to the fetus.
Applications: Used in cases of chromosomal abnormalities, blood disorders, infections, and blood incompatibility. It is particularly important for providing a rapid diagnosis in cases where amniocentesis has been performed too late.
Possibility of Blood Transfusion: When severe fetal anemia is detected due to blood incompatibility, a blood transfusion can be given to the fetus via cordocentesis. This is a critical intervention for protecting the health of the fetus.
Risk of Pregnancy Loss: The risk of pregnancy loss after cordocentesis is between 1-2%. This risk is associated with complications that may occur during the procedure. There is also a risk of infection after the procedure, which is why follow-up afterward is important.
Follow-Up After the Procedure: The expectant mother is advised to rest after cordocentesis and to follow the doctor's recommendations. Following procedures such as blood transfusion, the fetus's health status should be closely monitored.
Results of Invasive Tests and Communication with the Family
The results of invasive tests are generally available within 1-2 weeks. These results provide important information about the fetus's genetic condition and any possible abnormalities. If the test results show that the fetus has a serious genetic disorder or abnormality, the family is given detailed information about the situation. Doctors provide comprehensive counseling to help the family understand this information and evaluate the possible options. During this process, the family is informed about options such as termination of the pregnancy, special care requirements, or other medical interventions.
Conclusion
Invasive tests during pregnancy are critically important for assessing the genetic and structural health of the fetus. These tests make it possible to detect potential genetic disorders and structural abnormalities in the fetus at an early stage. Although these tests carry certain risks, they play an important role in pregnancy management because they offer the possibility of accurate diagnosis and early intervention. The decision to undergo invasive testing should be made by the family after considering the risk factors and receiving detailed information from their doctor. In this process, it is important for doctors to provide clear and comprehensive information to enable the family to make an informed decision.