The prenatal examination items required during different stages of pregnancy may vary, so pregnant women need to regularly visit the hospital for prenatal examination under the guidance of a doctor. Among them, color Doppler ultrasound is a necessary prenatal examination item for every pregnant woman. However, color Doppler ultrasound can also be divided into many different types, such as the more common three-dimensional and four-dimensional ultrasound. So when is the latest time to perform four-dimensional ultrasound during pregnancy?
1. Clinical recommendations suggest that pregnant women need to undergo 3-4 times of four-dimensional ultrasound examination during the entire pregnancy period. NT examination, i.e., nuchal translucency examination, should be performed during weeks 11-14 of pregnancy; four-dimensional ultrasound examination should be performed during weeks 24-28 to determine whether the fetus has structural abnormalities; another ultrasound examination should be performed during weeks 30-32 to re-verify any fetal malformations; and ultrasound examination should be used to assess amniotic fluid volume, placental function, and fetal weight during the full-term period.
2. Firstly, four-dimensional ultrasound mainly examines facial deformities, focusing on observing whether the fetus's eyes and eye sockets are of equal size and shape, measuring eye distance, and checking for any discontinuities in the hard palate, soft palate, and upper lip arcuate curve. Next, the neck of the fetus is screened for any abnormal masses.
3. Spinal deformities are examined by focusing on whether there are any bulges or interruptions in the light bands of the spine, whether there is any disorder in the arrangement, and whether there are any masses at the sacrococcygeal region. Other deformities such as abdominal deformities and limb deformities can also be detected through careful observation.
4. Four-dimensional ultrasound mainly examines neurological deformities such as anencephaly, hydrocephalus, microcephaly, spina bifida, and meningocele. Among the screenings for fetal malformations using four-dimensional ultrasound, cranial deformities are the first to be screened.
5. Four-dimensional ultrasound also examines digestive system deformities such as umbilical intestinal protrusion, evisceration, intestinal atresia, and megacolon. Other deformities such as short-limb deformities, conjoined twins, congenital heart disease, and teratomas can also be detected.
