What are the indications for an invasive procedure in Fetal Medicine (During Pregnancy)?
For a long time, there was a barrier between the fetus and the physician, with none able to reach or as we may say communicate with the other promptly. That barrier was the barrier of technology which has quite been lifted up during the past few years and is set to continue for the upcoming future.
Various scientific breakthroughs in recent years have allowed clinicians to draw conclusions about a child’s health and overall well-being that is still to be born into this world. Invasive procedures involve going directly into the environment of the fetus, which is the womb, either with a needle or some other specific instrument. There are certain situations when we need direct evidence from the fetus or its environment to confirm disease or syndrome with complete certainty.
Till about a decade ago, most of the invasive procedures in fetal medicine were indicated in the cases of advanced maternal age (> 35 years).In the current era, when new information is being added every day about the genetic basis of so many diseases and syndrome, due to advances in scientific technology, we are able to diagnose many fetal afflictions. Amniocentesis and CVS ie chorionic villous sampling are the two commonly done invasive procedures for reaching a diagnosis. Here in this article, we are going to reflect mainly on the various invasive procedures used in the prenatal diagnosis with a word on the treatment of fetal medical and surgical conditions.
Invasive procedures in fetal medicine can be divided into two major categories:
- DIAGNOSTIC PROCEDURES – to confirm the diagnosis that the baby inside the womb is affected by whatever the problem in question
- THERAPEUTIC PROCEDURES- done in some conditions where the treatment can be started while the baby still inside the womb.
DIAGNOSTIC PROCEDURES
Following is the list of diagnostic procedures:
- Amniocentesis
- Chorionic Villus Sampling (CVS )
- Fetal blood sample collection (Cordocentesis )
AMNIOCENTESIS:
During amniocentesis, a small sample of amniotic fluid (fluid surrounding the fetus during the pregnancy) is obtained and is tested in a laboratory. Amniotic fluid contains fetal cells and tissues along with various proteins, hormones, enzymes, and substances of diagnostic value.
Amniocentesis is advised to pregnant women for a variety of reasons. It is done after 15 weeks of pregnancy. Some conditions where amniocentesis is recommended are:
- When there is a high risk for chromosomal in the fetus as indicated during routine prenatal screening
- There is a history of genetic disorders in previous pregnancies or the parents are known carriers of a genetic mutation.
- For diagnosis of fetal infection
- Structural malformations in the fetus
- For drainage of excessive amniotic fluid in conditions such as polyhydramnios (excessive amniotic fluid during pregnancy).
CHORIONIC VILLOUS SAMPLING
In this test, a sample of chorionic villi is taken from the placenta and is examined for anomalies. It is usually done after 11 weeks of pregnancy.
Situations that prompt CVS test is:
- If the results of the first-trimester screen show a high risk for chromosomal disorders as Down syndrome.
- History of genetic disorders in a previous child like thalassemia, muscular dystrophies, or other syndromes related to global developmental delay and you want to rule it out in the current pregnancy or parents are carriers of a genetic mutation
- Structural malformations in the fetus
FETAL BLOOD SAMPLE COLLECTION /CORDOCENTESIS
Fetal Blood Sampling is a test where we take a small amount of fetal blood from the umbilical cord and test it for diagnosis and treatment of fetal abnormalities. It can be done anytime during the pregnancy after 18 weeks of gestation period.
Fetal blood sampling test is done for a variety of reasons such as:
- Detection of Chromosomal/Genetic Anomalies
- For detection of for presence of any infections.
- For diagnosis and treatment of severe anemia in the fetus.
- To give certain medications to the fetus for any existing conditions.
- Detection of hormones, platelets, metabolite levels
RISKS ASSOCIATED WITH DIAGNOSTIC INVASIVE PROCEDURES
Diagnostic procedures are usually safe. However, there is a very small chance of complications with amniocentesis and CVS as, miscarriage (2-4 in a 1000), preterm leaking (<1 in a 100 ) infection, and spots. The risk of fetal loss is higher with fetal blood sampling(1-2 %)
THERAPEUTIC /SURGICAL PROCEDURES USED IN FETAL MEDICINE
There is a whole list of interventions that are possible to treat only some conditions while the baby is inside so that the chances of survival of the baby, once born, improve. The discussion of these procedures is beyond the scope of this forum; though it would be prudent to name them
- Fetal reduction is reducing the number of fetuses inside when there are more than two or one is abnormal
- Fetal transfusion of blood while the baby is still inside the womb if it is severely anemic
- Laser ablation of blood channels between twins sharing a single placenta if there is an imbalance of fluid between the twins
- Various other techniques to seal the blood supply of vascular tumors of the fetus or placenta
- Draining fluid from around the lungs
- Certain fetal surgeries performed in highly specialized centers.
With these advances in fetal medicine, the possibilities of improving the outcome of pregnancy are increasing day by day, to ensure joyous parenthood and childhood for you and your child respectively.
