How to do Chorionic Villus Sampling

I believe everyone knows how to perform the chorionic villus sampling procedure, but I don’t know what diseases this procedure can be used to detect. Therefore, it is recommended that everyone should prepare for the surgery or learn related knowledge based on the doctor’s advice. The surgical method for chorionic villus sampling is to insert a very fine needle through the chorionic villus and then remove the chorionic villus tissue to check whether the fetus has chromosomal diseases.

How to do Chorionic Villus Sampling

Chorionic villus sampling is also called chorionic villus sampling. You may hear your doctor say CVS, which is actually the same thing. The purpose of chorionic villus sampling is mainly to confirm whether the fetus has chromosomal abnormalities, neural tube defects, and certain hereditary metabolic diseases that can be reflected in the amniotic fluid. So, how is chorionic villus sampling performed?

During the examination, a very fine needle is used to puncture the placental tissue and take out an appropriate amount of chorionic villus tissue for examination. There are 4 methods for chorionic villus sampling, which can be performed vaginally or abdominally, as follows:

1. Transcervical method. 2. Transabdominal method: The abdominal skin is locally anesthetized, and the puncture needle enters the villi of the placenta through the abdominal wall. A small amount of villi is sucked out with an empty syringe for examination.

2. Transabdominal method: The abdominal skin is locally anesthetized, and the puncture needle enters the villi of the placenta through the abdominal wall. A small amount of villi is sucked out with an empty syringe for examination.

3. Transvaginal method: Under the guidance of ultrasound scanning, the doctor inserts a catheter (a flexible thin tube) into the villus part of the placenta through the vagina and cervix, and uses an empty needle to absorb a small amount of villi for examination. Vaginal sampling is not recommended for patients with cervical lesions and reproductive tract infections, such as genital herpes, gonorrhea, and chronic cervicitis.

4. Through the bladder method . The earliest and most commonly used is the transcervical method.

All of the above methods require extracting chorionic villi from the placenta, with a total amount of 20 to 40 mg of villi.

Is chorionic villus sampling necessary?

Is it necessary to do chorionic villus sampling? Chorionic villus sampling is a type of prenatal examination, but it is not a mandatory item. However, if you are in the following situations, it is recommended that you undergo a chorionic villus sampling examination.

People with the following conditions are best to undergo chorionic villus sampling:

1. The patient has given birth to a child with congenital defects, especially a child with chromosomal abnormalities.

2. One of the spouses is a carrier of chromosomal abnormality or balanced translocation.

3. For carriers of sex-linked genetic diseases, when the sex of the fetus is determined in the second trimester of pregnancy.

4. Those who have given birth to a child with neural tube defects or whose serum alpha-fetoprotein level during this pregnancy is significantly higher than that of a normal pregnancy.

5. Pregnant women over 35 years old.

6. High risk screening for Down syndrome.

Warm reminder: Chorionic villus sampling is a prenatal examination item with high technical content. Expectant mothers should not go to some unknown hospitals for the sake of cheapness, but should go to regular hospitals for effective and scientific examinations to ensure the smooth birth of the baby.

2. Scope of venous puncture disinfection

Skin disinfection range for intravenous catheter puncture

The extent of skin disinfection for venipuncture should be determined by the type of venipuncture being performed:

The diameter of the skin disinfection range at the puncture site of a disposable intravenous infusion needle should be ≥5cm, and the diameter of the skin disinfection range at the puncture site of a peripheral venous indwelling needle should be ≥8cm. The puncture should be performed after the disinfectant has dried naturally.

The skin disinfection area at the puncture site of CVC (central venous catheter), PICC (peripherally inserted central venous catheter), and implanted vascular access should be ≥ 20 cm in diameter and at least larger than the dressing area (10 cm × 12 cm). With the puncture point as the center, slowly rotate from the inside to the outside and apply gradually. Disinfect the skin twice to establish a maximum sterile barrier. The puncture should be performed after the disinfectant has dried naturally.

IV catheter maintenance

Sterilize the catheter exchanger, needleless connector, and injection port before connecting the catheter

(1) Medical staff should perform hand hygiene and wear clean or sterile gloves before disinfecting the catheter connector.

(2) Before connecting the catheter interface, needleless connection system, and infusion port, use an ethanol-chlorhexidine solution or 75% ethanol wipe to vigorously wipe and disinfect the above areas for at least 15 seconds (ethanol-chlorhexidine has a longer residual activity compared to ethanol). Using ethanol wipes for wiping and disinfection has greater friction force than cotton swabs, and is more effective in mechanically removing microorganisms. (When drugs, fluids, and blood products are infused through a central catheter, contamination of the catheter connector is the most likely source of microorganisms for catheter-related bloodstream infection. Studies have shown that contamination of the fluid access has nothing to do with needle-free or needle-free connectors, but is related to whether the septum is adequately disinfected before puncture. Therefore, proper disinfection of the central venous catheter connector is an important measure to prevent catheter bloodstream infection.)

For non-access central venous catheters in adults and children, change the transparent dressing every 5–7 days or immediately if it becomes soiled, loose, or wet and disinfect with chlorhexidine. Change the gauze dressing every 2 days or sooner if it becomes soiled, loose, or wet.

⑴. In specific neonatal intensive care units, children should reduce the frequency of dressing changes to reduce the risk of catheter displacement.

⑵. If water seepage occurs at the catheter outlet, use gauze dressing instead of transparent dressing until the water seepage stops.