Chorionic villus aspiration (CVA) is a procedure that uses a puncture needle to aspirate chorionic villi from the uterine cavity and is performed at 11-14 weeks of gestation to diagnose chromosomal abnormalities and certain inherited metabolic disorders in the fetus. It is important to note that a normal chorionic villus test only means that there is no chromosomal abnormality and does not rule out non-chromosomal disorders such as cleft lip and palate.
What is Chorionic Villus Puncture
Chorionic Villus Puncture is a method of confirming fetal chromosomal abnormalities in the shortest possible time, and is usually scheduled for mothers-to-be who need it to be performed at 11-14 weeks of pregnancy. After confirming the position of the fetus and placenta through ultrasound, chorionic villus is scraped from the cervix or abdominal or vaginal wall for analysis. Although chorionic villus testing can be performed about 1 month earlier than amniocentesis, it is also more likely to cause fetal damage than amniocentesis because it is performed in the early stages of pregnancy.
Amniocentesis, do it? Don't do it? What to know before and after amniocentesis What is chorionic villus aspiration?What is Chorionic Villus Puncture
Chorionic Villus Puncture is a genetic diagnostic sampling tool that can diagnose whether a fetus has Down syndrome, or other chromosomal genetic disorders, by doing fetal chromosome analysis. Chorionic villus aspiration is 99% accurate, but it is expensive and has a higher risk factor than amniocentesis, making it suitable for mothers-to-be who have a higher chance of having a deformed baby.
Is Chorionic Villus Puncture Necessary
Doctors may recommend chorionic villus puncture in the 11th-12th week of pregnancy if the expectant mother is 35 years of age or older, has ever been pregnant with, or has ever given birth to, a defective fetus or if there is any history of genetic disorders in the family. Chorionic Villus Puncture is performed earlier than Amniocentesis and is performed to confirm the possibility of chromosomal abnormalities in the fetus if the maternal serum has been tested and the risk is high. In the case of an ordinary, normal, healthy mother-to-be, chorionic villus aspiration is not necessary.
Nowadays, the technology of chorionic villus penetration has been very sophisticated, although this test has a 0.5%-1% chance of miscarriage, which is not higher than the chance of spontaneous abortion; other water breakage, the chance of infection is also very low, after weighing the importance of the necessary implementation of the mother-to-be do not have to worry too much. However, it is important to note that chorionic villus puncture requires a high degree of skill and equipment, so be sure to go to a regular large hospital, under the guidance of an experienced doctor.
Who needs to have a chorionic villus test
1, who has given birth to a child with congenital defects, especially a child with chromosomal abnormalities.
2. One of the spouses is a carrier of a chromosomal abnormality or a balanced heterozygote.
3. Carriers of sex-linked genetic diseases, when determining the sex of the fetus in mid-pregnancy.
4. Those who have given birth to a child with neural tube defects or whose serum alpha-fetoprotein value is significantly higher than that of a normal pregnancy in this pregnancy.
5. Mothers of advanced maternal age (age 35 years or older) who are concerned about possible fetal abnormalities.
6. Mothers-to-be with high risk of Down syndrome screening during pregnancy.
7. Mothers-to-be whose spouses are carriers of the same type of thalassemia.
8, Ultrasound suggests abnormal fetal structure.
9. Known or suspected genetic diseases in the family, such as hemophilia and phenylketonuria.
How to do chorionic villus puncture
1, transvaginal sampling method: the examined mother-to-be lying down, knees bent, supported by stirrups or knee stirrups; guided by ultrasound scanning, the doctor used a long thin needle (length of about 30cm, inner diameter of about 1.5mm metal tube) through the vagina, the cervix to send into the chorionic portion of the placenta, with the empty syringe A small amount of chorionic villi is aspirated and sent for examination. The extracted tissue, when viewed in culture fluid, is shaped like chorionic villi. Usually about 40 milligrams are drawn. With cervical lesions, reproductive tract infections, such as genital herpes, gonorrhea, chronic cervicitis, etc., should not be transvaginal sampling.
2, transabdominal sampling method: If the location of the placenta is closer to the forearm of the uterus, it can also be punctured from the abdomen. Abdominal skin local anesthesia, chorionic villus puncture can check out the disease program and amniocentesis is similar, but the chorionic villus and the fetus have the same cells, so there is no need to go through the step of cultivation, and its chromosome and gene count will be sufficient. For some diseases, such as alpha-marine anemia, which requires a large amount of DNA, chorionic villus sampling can screen for more abnormalities because of the sufficient number of cells.
When to do Chorionic Villus Puncture
Chorionic Villus Puncture is usually scheduled for 11-14 weeks. Chorionic villus is performed earlier than amniocentesis, which can lead to certain fetal limb abnormalities if performed earlier than the 10th week of pregnancy, and is performed after the 11th week to avoid this risk. Answers are usually available within 2 weeks of having the test done. In general, abortion is best performed within 14 weeks, otherwise it can be bad for the mother. Therefore, if a fetus is found to have a major genetic disease, chorionic villus puncture can diagnose it in a short period of time, and abortion can be performed early with minimal risk to the mother. If the results of chorionic villus sampling are normal, it does not mean that 100% will give birth to a healthy fetus, because congenital defects in human limbs account for 2-3%, which are not included in the chorionic villus test.
Normal chorionic villus test values
A normal chorionic villus test only means that there are no chromosomal abnormalities, and it does not rule out other non-chromosomal disorders, such as congenital heart defects, mental retardation, or cleft lip and palate, as well as problems caused by genes. In other words, even if the chromosomal test is normal, about 2% of babies are born with a physical abnormality.
Interpreting Chorionic Villus Data
Chorionic villi are used to determine the sex of a fetus because the chromosomal karyotype of the chorionic villus cells is consistent with that of the embryo. When a fertilized egg develops into a blastocyst, a layer of trophoblast cells appears on the surface of the blastocyst in contact with the endometrium, and a number of villous projections form on the surface of the trophoblast cells, which are called chorionic villi. They will be very developed in the 7th-9th week of pregnancy, and if you can collect the villi and analyze the karyotype, you will know the sex of the fetus.
However, chorionic villus biopsy is an invasive test that can lead to fetal malformations. The risk of miscarriage due to chorionic villus biopsy ranges from 0.5% to 1%, and the risk depends on the experience and skill of the physician performing the chorionic villus biopsy.
In addition, the identification of fetal sex must have strict medical indications, and the implementation of fetal sex identification is only considered if the fetus may have X-linked genetic diseases due to genetic factors. The state has strict regulations on the conduct of fetal sex identification, only through the technical access, have the conditions of some hospitals can be carried out, and this prenatal diagnostic technology has a strict code of practice. Therefore, if it is not based on the possibility of genetic disease in the fetus, sex determination of the fetus is not desirable.
How much does a chorionic villus test cost
The price of a chorionic villus test varies from city to city and from hospital to hospital, so you should consult your local hospital. How much does a chorionic villus puncture cost? In the First Affiliated Hospital of Guangxi Medical University, for example, it costs about 2,000 yuan to do a chorionic villus puncture plus the examination fee, and a little more than 2,000 yuan for the Guangzhou Women and Children's Medical Center.