What to check for during the 20th week of pregnancy

What to check for during the 20th week of pregnancy is a question that many people are very concerned about. Every parent hopes that their baby is healthy and smart. The 20-week check-up for pregnant women is also very important. During this period, a routine blood test should be done first. A four-dimensional color ultrasound examination is also very important. Imaging examinations can help detect whether the fetus has malformations, such as cleft lip, spina bifida, polydactyly, etc. Let’s take a closer look at what to check for during the 20th week of pregnancy.

You are 20 weeks pregnant and this week you will have your third prenatal check-up, the most important of which is the B-ultrasound fetal malformation examination.

1. Routine prenatal examination items:

The third prenatal check-up is at 20 weeks of pregnancy. Routine examinations will include blood pressure, weight, blood routine, urine routine, abdominal circumference, uterine height, and fetal heart rate. Through these examinations, the doctor can get a general understanding of the physical condition of the pregnant woman, see if there are any abnormalities, whether the fetus is developing at a normal rate, etc.

2. Key prenatal examination items: B-ultrasound (deformity screening)

Necessity of B-ultrasound (for fetal abnormality screening): B-ultrasound examination is arranged in the second trimester because there is relatively more amniotic fluid in the uterus at this time, the fetus is of moderate size, and there is a larger space for movement in the uterus. For B-ultrasound examination, there is better contrast, and the various organs of the fetus can be clearly seen. More obvious malformations, such as congenital heart disease, anencephaly, hydrocephalus, spina bifida, abdominal wall defect, short limbs, polycystic kidney disease, and gastrointestinal atresia are easy to detect. If necessary, timely treatment or termination of pregnancy can be carried out.

1. B-ultrasound (malformation screening) function: Three-dimensional color ultrasound or four-dimensional color ultrasound can reflect the development of the fetus's face and organs through imaging, and is used to detect and screen fetal malformations, providing an accurate scientific basis for the early diagnosis of congenital surface malformations and congenital complex malformations of the fetus. At the same time, it can clearly display diseases such as fetal polycystic kidney disease and renal dysplasia, and is of great value in judging the fetal heart in utero.

2. B-ultrasound (deformity screening) examination method:

(1) Make an appointment at the hospital in advance to avoid missing the best examination time.

(2) Go to the hospital for fetal anomaly examination as scheduled. Taking four-dimensional color ultrasound as an example, under normal circumstances, a four-dimensional color ultrasound takes 30 minutes, but the time required may vary depending on the situation of each expectant mother.

(3) If the fetal position or other reasons make it difficult to see the fetus' face or other parts, the doctor will recommend that the expectant mother move around before continuing.

(4) The doctor will examine the baby very carefully. If any abnormal changes are found in the fetus, it will take longer. The main focus of the examination is on the fetus's head, such as cleft lip, poor development of the brain and bones, kidneys, heart, spina bifida, etc. Expectant mothers should not be nervous during the examination to avoid affecting the normal activities of the fetus and interfering with the examination results.

3. Normal values ​​of B-ultrasound (fetal anomaly screening): Due to the large activities of the fetus in the uterus, different body positions, differences in physician operations, etc., the numbers may cause errors, and sometimes even fluctuate greatly. Therefore, when the report results are different from the normal values, expectant mothers do not need to be overly nervous. If you have any questions, you can consult your obstetrician at any time.

(1) Common normal values ​​of fetal development during pregnancy by B-ultrasound examination (the following data are all average values):

Gestational age Biparietal diameter Abdominal circumference Femoral length

24 weeks of pregnancy 6.05±0.50 18.74±2.23 4.36±0.51

25 weeks of pregnancy 6.39±0.70 19.64±2.20 4.65±0.42

26 weeks of pregnancy 6.68±0.61 21.62±2.30 4.87±0.41

27 weeks of pregnancy 6.98±0.57 21.81±2.12 5.10±0.41

28 weeks of pregnancy 7.24±0.65 22.86±2.41 5.35±0.55

(2) Other data

Inspection Item Normal Value Risk

Cerebellar transverse diameter (length of cerebellum at level) 25 weeks: 2.85±0.17cm

30 weeks is 3.86±0.34cm. This data can measure the actual gestational age, so it can be used to evaluate whether the actual gestational age is consistent with the estimated gestational age.

If the lateral ventricle is smaller than 1cm and exceeds the normal value, it may be a developmental abnormality of the central nervous system - abnormal brain development, meningocele, cerebral hemorrhage, tumor, etc.

Posterior fossa cistern <0.1cm If it exceeds normal, there is a risk of complete or partial absence of the cerebellar vermis or Dandy-walker malformation.

The placenta is between 2.5-5.0cm. If the value is too small, the small placenta can lead to intrauterine growth retardation of the fetus and low birth weight at full term.

The fetal heart rate is 120-160 beats per minute. Abnormal values ​​indicate that the fetus may be suffering from intrauterine hypoxia.

Bilateral renal pelvic separation is less than 0.6cm. If the value is abnormally enlarged, the fetus is at risk of hydronephrosis.

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Tips for prenatal check-up at 20 weeks of pregnancy

1. Pay attention to your dress. Color Doppler ultrasound examines the fetus in the uterus, so before going for the examination, it is best for the expectant mother to wear separate tops and bottoms to make it easier for the doctor to examine her.

2. Relax appropriately. If a pregnant woman is nervous before having a color ultrasound, she should relax appropriately to relieve the tension to prevent her nervousness from affecting the normal activities of the fetus and interfering with the normal test results.

3. No need to fast or hold urine. There is no need to fast or hold urine for fetal malformation screening. As long as the pregnant woman goes to a regular hospital for examination within the examination time of four-dimensional color ultrasound, fetal malformation screening can be performed. Pregnant women can eat something and drink some water half an hour before doing the color Doppler ultrasound to increase fetal movement.

4. The next prenatal check-up will be conducted at the 24th week of pregnancy. The next prenatal check-up will require a sugar screening. Expectant mothers should remember to reduce the intake of starch and sugar in the two weeks before the examination.