What Is Fetal Nuchal Translucency?
Zona pellucida
- Chinese name
- Zona pellucida
- Foreign name
- nuchal translucency
- Attributes
- Anatomical term
- The cervical zona pellucida refers to the thickness of fluid accumulation in the subcutaneous tissue behind the fetal neck. Partial normal embryonic upper limb lymphocytes may have a short-term reflux disorder and temporary thickening of the transparent layer before 14 weeks. By about 14 weeks, after the left and right lymph vessels of the embryo communicate with the jugular sinus, the transparent layer gradually becomes thinner and disappears. The thickening of the cervical zona pellucida is closely related to various fetal congenital abnormalities, such as chromosomal abnormalities, Cardiovascular system abnormalities. Therefore, as an effective detection index, measuring the thickness of cervical zona pellucida has been widely used in screening for fetal chromosomal abnormalities.
- A large number of studies have confirmed that the thickening of the cervical zona pellucida is associated with abnormal fetal aneuploid karyotypes, of which trisomy 21 is the most common. Its incidence increases with the increase of the mother's reproductive age. However, most pregnant women At 35 years old, the mothers of most newborns with chromosomal abnormalities are over 35 years old. [1]
- The standard measurement method is to measure the thickness of the cervical zona pellucida on the sagittal section of the carcass, showing the longitudinal section of the contour of the fetal back, and the fetal head and spine in a straight line. On this section, the measurement point is placed on the inner edge of the two hyperechoic lines for measurement, that is, the neck transparent zone between the skin echo and the cervical fascia layer; the neck skin measurement should be placed on the outer edge of the occipital skull and The outer layer of the skin; a high-resolution real-time ultrasound diagnostic instrument is required, and the measurement accuracy should reach 0.1mm. When there is cervical meningocele, cervical umbilical cord should be identified to avoid misdiagnosis. If transabdominal ultrasound measurement is difficult, transvaginal ultrasound measurement can be used instead. There are also some differences in the measured values between different operators. Therefore, the measurement of the thickness of the cervical zona pellucida requires the ultrasonic diagnostic personnel to correctly grasp the standard cuts and methods of the measurement in order to reduce human error. [1]