Chorionic biopsy: early prenatal diagnosis

According to medical research, fetal genetic abnormalities occur in about 3-5% of all pregnancies and are accompanied by serious chromosomal abnormalities. Detecting these conditions at an early stage allows you to make important medical decisions in time and plan further pregnancy management.

For this reason, early prenatal diagnostic procedures are used in clinical practice to assess the condition of the fetal genetic material before symptoms develop. A chorionic biopsy provides accurate information about possible chromosomal and genetic disorders and helps doctors and parents act in a timely and informed manner.

Chorionic functions in early pregnancy

The chorion is the shell of the fetal egg, the outer germ layer that forms in the early stages of embryonic development. By the 16th week of gestation, it gradually transforms into the fetal part of the placenta, providing nutrition, gas exchange, and protection for the fetus.

The main functions performed by the chorion:

• embryo nutrition – provides nutrients from the mother;
• gas exchange – transports oxygen to the fetus and removes carbon dioxide;
• hormonal support – produces hormones (in particular, chorionic gonadotropin) that support pregnancy;
• barrier function – partially protects the fetus from infections and toxins;
• Placenta formation – the outer villous membrane of the fetal egg forms the placenta, which performs vital functions throughout pregnancy.

What is a chorionic biopsy?

Chorionic biopsy is a procedure for taking a small sample of chorionic villi for laboratory testing. The cytogenetic analysis of chorionic cells allows for early prenatal diagnosis of genetic abnormalities and congenital diseases in the fetus with an accuracy of up to 93%.

The chorionic villus biopsy procedure is usually performed between 9 and 14 weeks of pregnancy, when the membrane has already formed sufficiently for safe and accurate genetic testing. Closer to the 14-15th week of pregnancy, the chorion develops into the placenta, so the biopsy of the villi is limited in time.

When to prescribe chorionic villi examination

A chorionic villus biopsy allows you to accurately assess the chromosome set of the fetus and identify genetic abnormalities in the early stages of pregnancy. The diagnostic procedure helps to timely assess the health of the unborn child and determine the risks of developing serious diseases, including Down syndrome, and plan further pregnancy management.

The main indications for chorionic biopsy:

• increased risk of chromosomal abnormality according to the results of screening or ultrasound;
• the mother’s age is over 35;
• maternal serum test results indicate an increased risk of chromosomal abnormalities in the fetus;
• the presence of genetic diseases in parents or relatives;
• previous pregnancies with chromosomal abnormalities, including Down syndrome;
• early miscarriages or problems with pregnancy;
• clarifying diagnostics is required in case of discrepancies between other prenatal tests.

Advantages of chorionic biopsy compared to amniocentesis

Chorionic villus biopsy is an invasive diagnosis, but it allows you to obtain genetic information about the fetus earlier than with amniocentesis. This makes it possible to make medical decisions earlier in pregnancy.

Advantages of cytogenetic study of chorionic villi:

1. Early conduct. The optimal period for biopsy is 10-13 weeks of pregnancy, while amniocentesis is performed after 15 weeks.
2. High accuracy. The probability of correct detection of chromosomal abnormalities, including trisomy 21 (Down syndrome), exceeds 99%.
3. Smaller amount of material. To determine the chromosomal set of chorionic cells, 5-20 mg of villi is enough for a complete genetic analysis.
4. Fast results. A standard karyotype is obtained in 7-10 days, and modern molecular methods (FISH, CMA) in 2-3 days.
5. Possibility of early planning. Decisions on pregnancy management can be made 1-2 months earlier than with amniocentesis.

How a chorionic biopsy is performed

The chorion is the outer layer of the ovum, which has numerous villi at the point of contact with the uterus. The chorionic villi are immersed in the mucosa, providing nutrition to the fetus, and they are taken for examination without directly affecting the embryo. The procedure is safe and relatively painless and is usually performed on an outpatient basis.

Preparation for diagnostics and necessary tests

Before a chorionic biopsy, the patient is usually prescribed:

• ultrasound examination to accurately determine the position of the fetus and chorion;
• general and biochemical blood tests;
• analysis for infections that may complicate the procedure;
• consultation with a geneticist to assess risks and choose a research method.

Stages of the procedure under ultrasound control

A chorionic villus biopsy is a precise and controlled procedure that allows you to safely obtain a sample for genetic analysis. It takes place in several sequential steps:

1. Preparation of the patient. The woman lies down on a special examination table. The procedure is performed under the control of ultrasound of the anterior abdominal wall. The access area is treated with an antiseptic and, if necessary, light anesthesia is applied.
2. Entering a tool. Next, a special puncture needle or catheter is inserted into the chorion through the cervix or abdominally, depending on the location of the chorion.
3. Sample collection. A small amount of tissue containing chorionic villi is aspirated. The fetus is not affected, so the procedure does not harm it. The sample is immediately sent to the laboratory for further genetic testing.

The procedure lasts an average of 15-30 minutes. The patient stays under medical supervision for some time to make sure there are no complications.

Recovery is usually easy, and a woman can return home the same day. It is recommended to avoid physical activity and sexual intercourse for 24-48 hours after the procedure.

Results and conclusions of the study

After the chorionic biopsy, the sample is sent to the laboratory, where it is analyzed for chromosomal and genetic abnormalities. The conclusion usually states:

• number and type of chromosomes;
• structural or numerical abnormalities of chromosomal set are detected;
• the presence or absence of specific genetic mutations.

The conclusion of a cytogenetic test allows the doctor to learn about the health of the fetus, assess the risks of developing certain pathologies, but does not always make it possible to establish a definitive diagnosis. To confirm some conditions, additional tests or consultation with a geneticist may be required to make medically informed decisions about further pregnancy management.

What pathologies can be detected by biopsy

Biopsy of chorionic villi can reveal a wide range of chromosomal abnormalities and deviations:

1. Trisomies. Presence of an additional chromosome: trisomy 21 – Down syndrome, trisomy 18 – Edwards syndrome, trisomy 13 – Patau syndrome.
2. Monosomies. Absence of one chromosome, for example, Shereshevsky-Turner syndrome (monosomy X).
3. Chromosomal deletions and duplications. Loss or doubling of chromosomes, which can cause various genetic diseases.
4. Translocations and inversions. Structural disorders of the chorionic chromosome set, which may not be manifested in parents but affect the development of the fetus.
5. Mosaicism. The presence of different chromosome sets in different fetal cells.

Modern molecular methods of research (CMA, FISH, NIPT in combination with biopsy) allow diagnosing even minor chromosomal abnormalities and clarifying the risks of developing serious pathologies.

Why you should choose IVMED fertility clinic in Kyiv

At the IVMED Medical Center, women can receive comprehensive care – from diagnosing female infertility to reproductive technologies and high-precision prenatal examination. We provide pregnancy support at all stages, adhere to modern protocols, and guarantee attentive and tactful treatment of patients.

Advantages of the IVMED clinic in Kyiv:

1. The specialists of our clinic have many years of experience in chorionic biopsy and other prenatal procedures.
2. Safe sampling of placenta and chorionic villi for precise genetic testing, which allows for early detection of abnormalities.
3. High accuracy of results and individual approach to each patient.
4. Comfort, care and support for women at all stages of diagnosis.

Thanks to the high professionalism of our doctors, thousands of healthy children have already been born, and we continue to support safe pregnancy management for women regardless of age, health status, or medical history.

Don’t put off the important things! To get professional support and confidence in the health of your unborn child, make an appointment for a consultation at the IVMED clinic at a time convenient for you.