The difference between minor and major fetal anomalies, pregnant mothers should know it early

Women need to undergo two types of examinations during pregnancy: major fetal malformation screening and minor fetal malformation screening. Many expectant mothers do not understand this and think that both major fetal malformation screening and minor fetal malformation screening have the word "fetal malformation screening" in their names, so they should both be screenings to exclude fetal malformations. But why do they have to be done twice? In fact, there are differences between major fetal malformation screening and minor fetal malformation screening, and neither examination can be ignored.

As the name suggests, an fetal abnormality screening test is a test that women undergo in the early stages of pregnancy in a hospital or maternal and child health care center to rule out the possibility of a fetus with abnormalities. Generally speaking, pregnant women should go to the hospital for check-up around 20 weeks of pregnancy, and preferably not more than 28 weeks. Fetal anomaly screening is divided into minor fetal anomaly screening and major fetal anomaly screening.

Minor fetal anomaly screening is done at the 18th week of pregnancy, using black and white B-ultrasound. The major fetal anomaly screening is usually done in the 24th week of pregnancy, with 3D or 4D color B-ultrasound to check the development of the baby's organs. During this period, the baby's organs are fully developed, the amniotic fluid is moderate, and the baby is not too big, so a 3D (4D) color ultrasound can provide a clearer view.

Each B-ultrasound is a process of screening for fetal abnormalities. Generally, it is done 3-4 times during the whole pregnancy. If there are special circumstances, the number of times needs to be increased. The first time: 6 to 8 weeks of pregnancy, to check for fetal heartbeat and fetal bud, to rule out ectopic pregnancy or abnormal pregnancy (hydatidiform mole, etc.). If there is no spotting or abdominal pain, the first B-ultrasound can be omitted. Second time: 11 to 14 weeks of pregnancy, screening of the fetal nuchal translucency to assess the risk of fetal chromosomal abnormalities. The third time: 24 to 28 weeks of pregnancy, major malformations are screened, including anencephaly, encephalocele, open spina bifida, chest and abdominal wall defects, visceral eversion, single-chamber heart and other malformations. This ultrasound examination is particularly important. The fourth time: 37 to 40 weeks of pregnancy, to understand the fetal size, fetal position, placental position and maturity, amniotic fluid volume, whether the fetus has the umbilical cord around the neck, etc.