What is the Second-Level Screening in Obstetrics?

Obstetric secondary screening is a laboratory-based screening process that identifies high-risk or low-risk pregnant women by examining hematological indicators, biochemical markers and indices, immunological and microbiological indicators, and genetic indicators of the pregnant woman and/or her husband.

1. The primary screening system is clinical screening, which involves clinical observation and physical examination of the pregnant woman and her husband, combined with factors such as age, past medical history, past reproductive history, family genetic history, and exposure history of teratogenic factors, to determine high-risk or low-risk pregnancies.

2. The secondary screening system is laboratory screening, which identifies high-risk pregnant women through the examination of hematological indicators, biochemical markers and indices, immunological and microbiological indicators, and genetic indicators of the pregnant woman and/or her husband.

3. The tertiary screening system is medical imaging screening, primarily manifested in the three defense lines of fetal ultrasonography. Tertiary screening is generally performed around the 14th week.

1. Secondary Screening

Secondary screening differs from 4D ultrasound. Secondary screening primarily involves laboratory tests, which often include blood sampling. 4D ultrasound, on the other hand, belongs to tertiary screening.

2. 4D Ultrasound

4D ultrasound is typically performed around the 24th week. It can clearly visualize the baby's face, limbs, and internal organs to detect any malformations. It is a valuable test, differing from Down's syndrome screening, which focuses on the risk of 21 and 18 trisomy syndromes. 4D ultrasound directly reveals any surface malformations in the baby, which can also be detected by regular ultrasound but not as clearly or accurately as 4D ultrasound.