What Are the Different Types of Prenatal Screening?

Prenatal examination refers to providing a series of medical and nursing recommendations and measures for pregnant women. The purpose is to prevent and detect complications early by monitoring pregnant women and fetuses, reducing their adverse effects, and providing correct inspection methods and Medical advice is key to reducing maternal and perinatal mortality.

Basic Information

English name

prenatalexamination

Visiting department

Obstetrics and Gynecology

Contagious

no

Prenatal checkup time

According to the guidelines issued by the Perinatal Branch of the Chinese Medical Association, it is recommended that patients without complication of pregnancy be recommended to perform the first birth check at 10 weeks of pregnancy and register information. During pregnancy, 7 standardized birth checks are required, which are 16, 18-20, 28, 34, 36, 38. , 41 weeks; those who have not given birth before, should also increase once at 25, 31, 40 weeks, a total of 10 times. The number of prenatal check-ups for low-risk pregnant women is reasonable from 7 to 8 times during pregnancy, and the number of high-risk pregnant women is increased. The specific situation varies greatly depending on the individual condition.

Prenatal inspection

1. Ask for a detailed history

The content includes age, parity, occupation, menstrual history, understanding menarche age and menstrual cycle. If it is a pregnant woman, you should know the previous delivery situation, whether there is a history of dystocia, stillbirth, stillbirth, delivery methods, date of last delivery or abortion, Neonatal condition, previous history of hypertension, heart disease, etc. During this pregnancy, the time and extent of early pregnancy reaction, fever, viral infection and other discomforts, medication status, etc .; husband health status, family history of both parties Attention needs to be paid to birth defects and genetic diseases, and related diseases need to be recorded.

2. Estimated due date

From the first day of the last menstrual period, the number of months is reduced by 3 or 9 and the number of days is increased by 7. If the last menstrual period is March 5, its due date is December 12. It should be noted that pregnant women with irregular menstrual periods cannot mechanically use this method to determine the due date due to the abnormal ovulation time. Judgment can be based on the time when the early pregnancy reaction occurs, the start of fetal movement, and the height of the uterine fundus.

3. Whole body examination

(1) Height and weight / body mass index (BMI) Generally speaking, pregnant women with short stature have an increased chance of pelvic stenosis, and BMI values are related to pregnancy prognosis. Those with high BMI index need to be aware of complications such as pregnancy-induced hypertension and diabetes during pregnancy. Disease occurs.

(2) Blood pressure measurement Knowing the patient's basic blood pressure is of great significance in assessing and judging the tolerance of the circulatory system during pregnancy. For example, patients with chronic hypertension need to actively control their blood pressure early and need more professional guidance in life and diet. .

(3) Oral examination The current research shows that periodontitis is closely related to infectious preterm labor. Therefore, dental care during pregnancy is very important. Of course, it is very important to plan a thorough treatment of oral diseases before pregnancy.

(4) Auscultation of the heart and lungs to understand whether the heart has murmurs and whether there are basic lesions in the lungs, especially in pregnant women with a previous history of heart and lung disease, the burden is significantly increased during pregnancy, and further evaluation of cardiopulmonary function is needed.

(5) With or without edema in the lower limbs, normal pregnant women often have edema below the knee and subsides after rest. If it does not disappear and is accompanied by excessive weight gain, you need to be alert to the occurrence of hypertension during pregnancy.

4. Obstetric examination

(1) Measurement of uterine height and abdominal circumference The uterine height refers to the distance from the upper edge of the pubic bone to the bottom of the uterus. When the uterine floor exceeds the range of normal gestational weeks, it is necessary to consider whether it is a twin pregnancy, huge children and excessive amniotic fluid, especially the abnormal increase in amniotic fluid caused by fetal malformations. If the abdomen is too small, you need to pay attention to whether there are fetal intrauterine developmental restrictions and fetal malformations.

(2) Auscultation of fetal heart sounds The fetal heart sounds are often clearer on the dorsal side of the fetus. When the uterine wall is more sensitive, or other factors such as obesity that have caused difficulty in assessing the fetal position are helpful.

(3) Vaginal and cervical examinations Vaginal examinations are often performed during the first 6 to 8 weeks of pregnancy. Pregnant women who do not have a pre-pregnancy examination need to undergo routine cervical cytology to exclude cervical lesions. If abnormalities of cervical cytology are found, they should be used as appropriate. Have a colposcopy. In the third trimester, you can learn to perform pelvic measurement while performing a vaginal examination. The most important diameter line in pelvic measurement is the diameter of the ischial tuberosity, that is, the transverse diameter of the pelvic outlet plane. If the outlet plane is normal, you can choose vaginal trial production. Extrapelvic measurements are currently obsolete.

5. Auxiliary examination and its clinical significance

(1) Blood routine The blood routine examination is generally carried out in the first trimester and late pregnancy. Pregnant women's blood is diluted, the red blood cell count drops, and the hemoglobin value drops to 110g / L as anemia. Leukocytes increased from 7 to 8 weeks of pregnancy to 30 weeks and reached a peak, sometimes reaching 15 × 10 ⁹ / L, mainly due to the increase of neutrophils, which needs to be distinguished from clinical infectious diseases. Check the blood routine in the third trimester for anemia, and add iron in time.

(2) Urine routine The urine routine during pregnancy is the same as the non-pregnancy period, but due to the increase in vaginal secretions, there may be a certain interference with the results. It is necessary to pay attention to the urine protein in the second and third trimesters. Routine urine tests are required at every prenatal check-up.

(3) Examination of liver and kidney function During pregnancy, the burden of liver and kidney is increased. It is necessary to understand the liver and kidney function in early pregnancy. If there are basic lesions, further examination is needed to determine the type of disease to assess the risk of pregnancy. Some pregnancy complications such as preeclampsia and acute fatty liver during pregnancy can affect liver and kidney function. It needs to be monitored twice during early pregnancy and late pregnancy.

(4) Serological examination of syphilis Pregnant women suffering from syphilis need to be checked during pregnancy. If early pregnancy infection is caused by syphilis, treatment should be given according to the situation to reduce the damage of syphilis pathogens to the fetus.

(5) Hepatitis B surface antigen. Pregnant women with hepatitis B can be transmitted from mother to fetus and cause neonatal hepatitis B virus infection. Therefore, screening should be performed during early pregnancy. Hepatitis B immunoglobulin suppression is not recommended during pregnancy. Active immunity is required after birth. Combined passive immunization to prevent neonatal hepatitis.

(6) ABO and Rh blood types are mainly related to judging and preventing maternal and child blood group incompatibility. Rh Chinese negative blood is relatively rare, 3 to 4 . The blood type is determined because the Rh-negative pregnant women are Rh-positive and the fetal blood-type is Rh-positive, and the Rh blood group incompatibility between the mother and the child will cause intrauterine edema. In severe cases, the fetus should be treated in time. The risk of fetal hemolysis in the ABO blood group system is relatively small.

(7) HIV screening Screening is performed during early pregnancy, diagnosis of positive cases, and active treatment according to HIV infection treatment guidelines.

(8) Screening for gestational diabetes According to the requirements of the Ministry of Health's gestational diabetes industry standard, a 75g glucose tolerance test should be performed at 24 to 28 weeks of pregnancy, such as fasting blood glucose, as long as one of the 1 and 2 hours after taking glucose exceeds the threshold That is, the diagnosis of gestational diabetes mellitus, the critical values are 5.1mmol / L, 10.2mmol / L, 8.5mmol / L. High-risk pregnant women can be screened in advance or repeated screening according to the situation.

(9) Serological screening for pregnant women The hospitals that have been accredited by the provincial and municipal health bureaus have performed various relevant serological screening tests according to the different conditions of each hospital. Early pregnancy screening test refers to 11 ~ 13 + 6 weeks of pregnancy. Ultrasound should be used to determine the thickness of the fetal neck clear layer (NT) or comprehensive detection of NT, maternal blood -HCG and pregnancy-related plasma protein A (PAPP-A). Find the risk value for Down syndrome. For screening pregnant women at high risk, villous biopsy (CVS) may be considered for prenatal diagnosis. Mid-pregnancy screening can wait until the second serological screening in the second trimester, and can combine the results of screening in early pregnancy or independently calculate the risk value to determine whether to perform prenatal diagnosis. 14 to 20 weeks of pregnancy is the window of screening during the second trimester, mostly serological duplex screening (AFP and free -HCG) or triple screening (AFP, free -HCG, free mE3). Serological screening results include risk values for trisomy 21, trisomy 18, and neural tube defects. The former two require further examination of karyotypes, while the latter only require systematic ultrasound examination.

(10) Ultrasound examination is the most important test item during pregnancy. Ultrasound examination at 7 to 8 weeks of pregnancy is helpful to determine whether it is an intrauterine pregnancy. If there are no abnormalities such as vaginal bleeding and abdominal pain at this stage, it is recommended that the first The timing of the ultrasound examination was 11 ~ 13 + 6 weeks of pregnancy, and the thickness of the transparent layer (NT) of the fetal neck was determined while determining the accurate gestational age. The second ultrasound examination was performed at 18 to 24 weeks of pregnancy. At this time, the structure of the fetus and the amount of amniotic fluid were the most suitable for systematic ultrasound examination. The fetus was screened for anatomical abnormalities, and the fetal skull, face, spine, Heart, abdominal organs, limbs, umbilical artery and other structures. Ultrasound soft indicators of chromosomal abnormalities in the second trimester include fetal neck clear layer thickness, fetal nasal bone loss or dysplasia, short humerus and femur, strong echo of intestine, abnormal heart structure, tricuspid regurgitation, intraventricular strong echogenic light spot, renal pelvis Dilation, choroid cysts, etc., can improve the detection rate of fetal aneuploidy. The third ultrasound examination was performed at 30 to 32 weeks of gestation in order to understand the status of fetal growth and development, the placenta position, and fetal exposure. The fourth ultrasound examination was performed at 38 to 40 weeks of pregnancy to determine the position and maturity of the placenta, the status of the amniotic fluid, and the estimated fetal size. Under normal circumstances, it is sufficient to perform 4 to 5 B-ultrasounds according to the above 4 stages during pregnancy. However, if abdominal pain, vaginal bleeding, frequent or reduced fetal movement, abnormal fetal development, and unclear fetal position occur during pregnancy, the number of inspections needs to be increased as appropriate. .

(11) Electronic fetal heart rate monitoring From 34 to 36 weeks of pregnancy , electronic fetal heart rate monitoring should be performed once a week. After 37 weeks, according to the situation, once or twice a week. If high-risk pregnant women, especially those at risk of reduced placental function, should increase the number of fetal heart monitoring.

(12) ECG examination During the first delivery examination and 32 to 34 weeks of pregnancy, an ECG was performed. Due to the increase in blood volume in the third trimester, it is necessary to understand the cardiac function of the pregnant woman. If necessary, an echocardiographic examination is required.

Prenatal examinations for special populations

1.TORCH screening

Including rubella virus (RV), toxoplasma (TOX), cytomegalovirus (CMV), herpes simplex virus (HSV) and others. If pregnant women have symptoms related to the above virus-related infections or abnormal fetal ultrasound examinations can be performed, if TORCH ~ IgM-positive patients need to determine whether they are the primary infection. Be aware that a maternal infection does not mean a fetal infection, and a confirmatory diagnosis is needed to confirm whether the fetus is infected.

2. Screening of fetal fibronectin and ultrasound assessment of cervical length

Tests can be performed on pregnant women at risk for late-term miscarriage or premature delivery to help predict the risk of adverse outcomes. Cervical length less than 2.5cm combined with FFN positive can be used to screen pregnant women with true preterm birth.

3. Screening for hypothyroidism

The incidence of pregnancy-associated hypothyroidism is approximately 0.9%, and screening can be performed for high-risk cases, but there is no evidence to support screening for hypothyroidism in all pregnant women.

Prenatal checkup

On the basis of genetic counseling, the process of definite diagnosis of high-risk fetuses, mainly through genetics and imaging, is of great significance for reducing the rate of birth defects and perinatal mortality and improving the quality of the population.

According to the industry management regulations of the Ministry of Health, prenatal diagnosis clinics are set up in medical institutions recognized by health administrative agencies, and genetically counseled or prenatal counseling by obstetrics and gynecology are performed by professionally trained doctors. Physicians should understand the personal and past history of pregnant women Indications for prenatal diagnosis to help pregnant women correctly understand the risk of fetal chromosome disease and the clinical manifestations of chromosome disease. At the same time, pregnant women should be made aware of the risks of various complications that may occur with interventional material extraction. Pregnant women over 35 years of age, or who meet other prenatal diagnostic indications, should be recommended for prenatal diagnosis.

Prenatal diagnosis indications for cytogenetics are as follows: elderly women over 35 years of age; pregnant women at high risk of abnormal fetal chromosomes detected by prenatal screening; pregnant women who have had children with chromosome disease; prenatal B-ultrasound Pregnant women suspecting that the fetus may have a chromosomal abnormality; the spouse is a carrier of the chromosomal abnormality; and other circumstances in which the physician believes that a prenatal diagnosis is necessary. Commonly used interventional prenatal diagnostic surgery: villus extraction, amniocentesis, and percutaneous umbilical puncture, the gestational weeks are 10 to 13 + 6 weeks of pregnancy, 16 to 22 + 6 weeks of pregnancy, and 18 of pregnancy After the week. The physician should choose the appropriate period and method for prenatal diagnosis. Before the operation, the physician should correctly grasp the indications and contraindications of the prenatal diagnosis and material extraction surgery, and complete the necessary inspections.