Guidelines on technical expertise in prenatal screening and diagnosis in the first 3 months of pregnancy in Vietnam

What are regulations on guidelines on technical expertise in prenatal screening and diagnosis in the first 3 months of pregnancy in Vietnam? 

Pursuant to Clause 1, Article 4 of the Guidelines for organization of prenatal and newborn screening, diagnosis and treatment promulgated together with Decision 1807/QD-BYT in 2020, stipulating prenatal screening and diagnosis in the first 3 months of pregnancy is as follows:

1. Screening and diagnosis of thalassemia major

The screening and diagnosis of thalassemia is done at gestational age before 21 weeks and is done as soon as possible.

1.1. Subjects, screening methods, diagnosis

a) Screening

- Subjects: Pregnant women in the first 3 months of pregnancy.

- Methods: Test for total analysis of peripheral blood cells.

b) Diagnosis

- Objects

+ Pregnant women whose screening results are suspected of carrying the Thalassemia gene;

+ The husband of the pregnant woman or the father of the fetus has a positive screening result;

+ Pregnant women with edematous status;

+ History of pregnant women who have had children with thalassemia or a history of hydrops.

- Method

+ Complete peripheral blood cell analysis with the husband of the pregnant woman or the father of the fetus;

+ Testing the hemoglobin composition of pregnant women, husbands of pregnant women or fathers of high-risk fetuses;

+ Testing the globin gene of pregnant women and the husbands of pregnant women or the father of the fetus;

+ Genetic testing from placental spines at 11 weeks to 14 weeks or amniotic fluid cells from 16 weeks of pregnancy;

+ Genetic diagnosis of thalassemia in the fetus.

1.2. Screening and diagnostic procedures

Pregnant women should be screened before 14 weeks of gestation in the following order:

- Total analysis of peripheral blood cells of pregnant women.

The risk threshold will be selected by the medical examination and treatment facility based on technical conditions, biological products, equipment, and scientific evidence.

According to the recommendations of the National Institute of Hematology and Blood Transfusion, the screening threshold for MCV is 85 fl and MCH is 28 pg.

+ If the test results are low-risk: instruct pregnant women to have regular antenatal check-ups as prescribed.

+ If the test results are high risk: consult a total peripheral blood smear test with the husband of the pregnant woman or the father of the fetus.

. If the test results with the husband of the pregnant woman or the father of the fetus are low risk: stop.

. If the test results with the husband of the pregnant woman or the father of the fetus are high-risk: counseling for testing to determine the hemoglobin composition of the pregnant woman and the husband of the pregnant woman or the father of the fetus pediatric. Test results will be analyzed by hematologists and/or genetic counselors to make a decision on genetic testing on a case-by-case basis.

- Testing the globin gene for pregnant women and the husbands of pregnant women or the father of the fetus. Based on the results of the globin gene test, the hematologist and/or genetic counselor will advise on a case-by-case basis.

- In case it is necessary to determine the fetal globin gene, it is indicated to take the placenta or amniotic fluid for diagnosis by appropriate techniques. Based on the diagnosis results, the hematologist and/or genetic counselor will advise on a case-by-case basis.

The procedure is shown in Diagram 1. Screening and diagnosis of thalassemia.

What is screening and diagnosis of some abnormalities in number of chromosomes and fetal morphology in the first 3 months of pregnancy in Vietnam?

Pursuant to Clause 2, Article 4 of the Guidelines for organization of prenatal and newborn screening, diagnosis and treatment promulgated together with Decision 1807/QD-BYT in 2020, stipulates screening and diagnosis of some abnormalities in number of chromosomes and fetal morphology in the first 3 months of pregnancy is as follows:

2. Screening, diagnosing some abnormalities in chromosome number and fetal morphology

2.1. Subjects, screening methods, diagnosis

a) Screening

- Subjects: Pregnant women in the first 3 months of pregnancy.

- Methods

+ Fetal ultrasound: to determine the number of fetuses, measure the length of the head and buttocks of the fetus with the aim of determining the gestational age of 11 weeks to 13 weeks and 6 days, surveying the fetal structure, measuring the light on the back of the neck, and the nasal bones and other signs.

+ Maternal blood test: in addition to the total analysis of peripheral blood cells to screen for thalassemia, PAPP-A (Pregnancy Associated Plasma Protein A) and free beta hCG (free beta human Chorionic Gonadotropin) to screen for chromosomal abnormalities.

To screen for chromosomal abnormalities, two PAPP-A and free beta hCG indices and ultrasound indices can be used on appropriate risk programs.

+ Testing fetal DNA circulating in the mother's blood (non-invasive prenatal screening technique - NIPT) to screen for fetal chromosomal abnormalities.

Recommendation: gestational week for NIPT testing should be ≥ 10 weeks after pregnancy ultrasound results and counseling by a genetic counselor for appropriate indications. This test can replace the PAPP-A and free beta hCG tests or supplement the above tests as the case may be.

b) Diagnosis

- Objects

+ Pregnant women with abnormal fetal morphology and/or screening results are at high risk of chromosomal abnormalities or certain genetic diseases.

Pregnant women are at increased risk of having a baby with a birth defect based on family history and diagnosis with appropriate techniques.

- Methods

Use appropriate ultrasound techniques to diagnose fetal abnormalities.

+ Use appropriate genetic testing techniques to identify genetic and chromosomal abnormalities.

2.2. Screening and diagnostic procedures

Pregnant women should be screened from 11 to 13 weeks and 6 days of pregnancy (calculating gestational age according to fetal head and rump length, minimizing gestational age based on the last menstrual period of pregnant women) according to the following sequence:

- Fetal ultrasound to determine the number of fetuses, position of the placenta, measure the length of the head and buttocks to determine the gestational age, examine the morphology and structure of the fetus, measure the light at the nape of the neck and other ultrasound signs (if necessary) to calculate the risk of trisomy 21, 18 and 13.

In case the ultrasound detects that the fetus has severe abnormalities, poor pregnancy prognosis, cannot be cured or cannot live after birth, consultation and consultation to terminate the pregnancy. In other cases, follow these steps:

- Perform prenatal screening test by immunohistochemical method to quantify PAPP-A and free beta hCG, combine clinical information, ultrasound to calculate the risk of fetal abnormalities on chromosomes 21, 18 and 13.

- In case a pregnant woman wants to perform a screening test using fetal DNA circulating in the mother's blood, this test can be performed from the 10th week of pregnancy. However, before that, it is necessary to have an ultrasound of the fetus and evaluate the mother's history to rule out some cases where this test cannot be indicated.

The risk threshold will be selected by the medical examination and treatment facility based on technical conditions, biological products, equipment, scientific evidence and risk calculation program.

+ If low-risk screening results (fetal ultrasound results, PAPP-A and free beta hCG test results or NIPT results): instruct pregnant women to have regular antenatal check-ups.

+ If high-risk screening results (fetal ultrasound results, PAPP-A and free beta hCG test results or NIPT results): counseling for prenatal diagnosis or counseling pregnant women only have a test for high-risk PAPP-A and free beta hCG substances as a screening test using fetal DNA circulating in maternal blood (to increase the efficiency of screening) before deciding to perform prenatal diagnosis.

Perform chorionic villus sampling (weeks 11 to 14) for prenatal genetic testing using appropriate techniques.

+ In case chromosomal abnormalities are not detected: instruct pregnant women to have periodic antenatal check-ups.

+ In case chromosomal abnormalities are detected: need consultation, if the pregnancy prognosis is bad, can't be treated or can't live after birth, will advise to terminate the pregnancy.

+ In case genetic testing is indicated, the genetic counselor will advise based on the test results.

The procedure is shown in Figure 2. Screening and diagnosis of some abnormalities in chromosome number and fetal morphology in the first 3 months of pregnancy.

Best Regards!