Fetal (in utero) Diagnosis is the name given to all procedures performed to diagnose problems that babies in the womb have. The purpose of using in utero diagnostic methods is to understand whether there is any problem with the baby, to form an opinion that the pregnancy is proceeding normally if no problem is found, to categorize the problem as if this problem is a life-threatening problem, is intervention necessary and appropriate after birth or should intervention be performed in the womb, and to allow efforts to be made for the management of this problem without delay.
The non-invasive methods we use for diagnosis in the womb are, as the name suggests, methods that do not cause any harm to the mother and baby. The most commonly used ones are ultrasonography, doppler, and magnetic resonance (MRI).
UltrasonographyThe most commonly used device by gynecologists and obstetricians for diagnosis in the womb is the ultrasonography device. Ultrasonography is used for diagnosis from the beginning to the end of pregnancy. In the early stages of pregnancy, ultrasonography gives us an idea about whether the baby is in or out of the womb, is it a single or multiple pregnancy, its development is compatible with its peers or not, its water (amniotic fluid) is sufficient or not, and it helps us in the diagnosis of some problems that can be seen with ultrasonography in later weeks of pregnancy. Thanks to ultrasonography, we can diagnose many problems related to the cerebrospinal system, face, thorax, heart, urinary system, anterior abdominal wall and extremities of babies while they are in the womb.
DopplerDoppler is a method that is available in almost all ultrasound devices today and can show us the flow rate of the fluids in the baby's blood vessels, heart, and everywhere else where fluids flow and the resistance in the vessels against this flow. It is a noninvasive method. There is no data showing that it causes any harm to the mother or the baby. By Doppler, we can calculate the flow rate of the baby's blood in the vessels, the resistance to the flow and the ratios of these to each other. In this way, we can understand whether the baby's basic needs such as oxygen are easily delivered to him. In addition, by looking at the blood flow and resistance of the vessels going to the uterus with Doppler, we can have an idea about whether the placentation is sufficient or not. Doppler examination also gives us information of the blood flow of the baby's middle cerebral artery and we understand whether the baby has anemia with almost 90% accuracy. Doppler is very useful for us in diagnosing problems in babies and treating these problems.
Magnetic Resonance (MRI)Ultrasonography is the most frequently used diagnostic method during pregnancy, but in some cases it is not sufficient to reach our desired goals in the evaluation of soft tissue. In such cases, magnetic resonance is one of the methods we frequently use. Especially in the diagnosis of problems related to the cerebrospinal system, ultrasound evaluation of structures within the skull and masses within the thorax is sometimes limited, so MRI is quite useful for us. Since it does not contain radiation like Computerized Tomography, MRI can be used safely during pregnancy.
Invasive methods used to diagnose the problems of babies in the womb are procedures that, as the name suggests, can potentially pose a risk to the mother or the baby. The most commonly used of these are procedures such as Chorionic villus sampling (CVS), amniocentesis, cordocentesis, fetal skin biopsy, and fetal liver biopsy.
CVS (Chorionic Villus Sampling)CVS, or chorionic villus sampling, is the process of taking a biopsy from the baby's placenta using a catheter under ultrasound guidance. Since the baby's placenta and the baby itself are formed by the division of a single fertilized egg, it is expected that the genetic material in the sample taken from the placenta will be the same as the baby's genetic material. Indeed, with a very small exception of half a percent, the genetic material of the baby and the placenta are the same. Therefore, instead of waiting until the 16th week to take a sample from the baby, genetic studies can be started by taking a sample from the baby's placenta by CVS, between the 11th and 14th weeks for genetic examination. The CVS procedure can be performed in outpatient clinic conditions without the need for the patient to be hospitalized, by simply numbing the mother's skin with local anesthesia. Ultrasonography guidance is required during the procedure. The procedure can be performed in a few minutes in experienced hands. The taken material is sent to the genetic laboratory in a special medium for genetic examination. The probability of losing the baby in the procedure is less than one in two percent. If there are any problems related to the procedure, they usually occur within 2 weeks. Again, during this procedure, a genetic examination may report a genetic disorder in the placenta with a probability of 1 in 200, even though there is no problem in the baby. This condition is called mosaicism limited to the placenta, etc. In such babies, although the babies are genetically normal, the risk of the baby being smaller than its peers in the future, etc., has increased due to mosaic structures in the placenta.
AmniocentesisAmniocentesis is the most common method used as an invasive diagnostic method in pregnancies. It is usually performed after the 16th week of pregnancy. The purpose of amniocentesis is to obtain fluid from the baby's amniotic fluid with the help of ultrasound and a catheter. The baby's fluid seen on ultrasound, namely amniotic fluid, consists mainly of the baby's urine. This fluid contains cells shed from the baby's urinary tract, skin, and respiratory system, as the baby draws and releases this fluid into its lungs. Therefore, the cells obtained with amniocentesis are the baby's own cells. They are not placental cells as in the CVS described above. Therefore, if any diagnosis is made with amniocentesis, this diagnosis is really a diagnosis of cells belonging to the baby.
Amniocentesis, like the CVS procedure described above, is performed as an outpatient procedure in outpatient clinics without hospitalization. After the area to be treated is cleaned with disinfectant, a catheter is directed to the amniotic fluid area under ultrasound guidance. After the catheter enters the amniotic fluid, 1-2 ml of fluid is taken from the mother to rule out possible maternal contamination and is not sent to the laboratory. After that, the fluid sample is taken and sent to the laboratory for genetic testing. Usually, 1 ml of amniotic fluid is taken per week of pregnancy. In other words, if the pregnancy is 16 weeks, 16 ml of amniotic fluid is sufficient. Since this fluid is mainly the baby's urine, since the baby continues to urinate continuously, no fluid deficiency occurs due to the removal of this fluid. The fluid removed is quickly replaced by the baby as urine.
Amniocentesis is a risky procedure because it is an invasive procedure. The probability of loss due to amniocentesis performed all over the world is reported to be around 1/200. However, this probability of loss includes all babies, including those who will be lost naturally due to their own problems inside, that is, in the womb. If the babies are healthy and the procedure is performed by an expert under appropriate conditions, the probability of fetal loss is less than one in a thousand. After the amniocentesis procedure, complications such as fluid leakage (amniorrhexis) or infection can rarely occur from the puncture site of the membrane punctured by the catheter. Most complications are seen within two weeks of the procedure.
CordocentesisCordocentesis is the process of taking a blood sample from the vein by entering a catheter into the vein of the umbilical cord of the baby in the womb. This procedure, similar to the above described two procedures, can be performed in outpatient clinic conditions without the need for hospitalization of the mother and without the need for any general anesthesia.
Cordocentesis is performed under outpatient clinic conditions with ultrasound guidance, like the previously described amniocentesis and CVS procedures. After the area is sterilized with disinfectants, a thin catheter is placed into the umbilical cord under ultrasound guidance. A blood sample of the baby is taken from the umbilical cord and sent to the laboratory for genetic examination or biochemical examination if it is performed for another reason.
Cordocentesis also carries the possibility of losing the baby, similar to the invasive procedures described earlier. While the risk of loss was reported to be roughly 0.5% in previous procedures, this risk of loss increases to 2-2.5% during the cordocentesis procedure. The reason for this is the possibility of bleeding from the hole in the umbilical cord.
There is another feature that distinguishes the cordocentesis procedure from the previously described diagnostic procedures. After entering the umbilical cord, a blood sample can be taken for diagnostic purposes and cordocentesis can be performed for treatment purposes. For example, if anemia is detected in the baby, during the cordocentesis procedure, both the baby's anemia can be fully evaluated and blood can be given to the baby while it is in the womb through the umbilical cord. In some cases, it may be necessary to give some medical agent or hormones to the baby in the womb through the blood. In such cases, cordocentesis can be performed to give the baby the blood or medical agents it needs through the umbilical cord.
