Question
I am 23 years old and 15 weeks pregnant. The results of my Down syndrome screening show an APF of 27.61g/ml, a MON value of 0.74, and an HCG level of 69550IU/L, with a MON value of 2.08. The risk of Down syndrome is 1 in 505, the risk of trisomy 18 is 1 in 23255, and the risk of neural tube defects is 0.74. Is my baby normal? Will they have Down syndrome?
Answer
Case Analysis: Hello, a low-risk indication for Down syndrome means the risk of the condition is relatively low. Alpha-fetoprotein (AFP) was initially used to diagnose open neural tube defects. When AFP levels are elevated, the sensitivity to diagnose anencephaly is greater than 98%, and the sensitivity to diagnose spina bifida is greater than 90%. Subsequent findings have shown that in cases with chromosomal aneuploidy, a maternal serum AFP level below the normal mean (MoM) of 0.75, combined with age-related risk factors, can identify about 25% of Down syndrome cases. The measurement of free beta-hCG can also improve the detection efficiency in the second-trimester Down syndrome screening. Free estriol (uE3) can also increase the detection efficiency by approximately 5%.