Monday, 17 August 2020

Aneuploidy risk assessment at first trimester : Probability Risk

 

 

Currently,  risk assessment has transitioned into the first trimester,. Various paradigms for first-trimester or integrated first- and second-trimester screening have resulted in the detection of 85% to 98% of fetuses with trisomy 21, with a false positive rate of 5%. As of now,  it is recommended that all pregnant women be offered prenatal screening for aneuploidy  Different  sonographic metrics in conjunction with serum analytes(So called Double markers)   are used to confer a patient- specific risk of aneuploidy.

What Is then, the Importance of Second Trimester “Soft Markers” ? Ans: Yes, second trimester scan has an important value but couple would like to know status of foetus as early as possible i,e at end of first trimester.  Currently,  risk assessment has transitioned into the first trimester, in which as mentioned earlier  that the sonographic metrics in conjunction with serum analytes are used to confer a patient- specific risk of aneuploidy. The nasal bone was recorded as “not requested” or if requested as “present,” “absent,” or “unable to obtain.” In the case of an absent nasal bone, 2 consecutive evaluations, typically 1 week apart, were required to definitively report the nasal bone as absent.

 

The question that remains is whether there is any importance to a soft marker for aneuploidy in the second trimester fetus with normal anatomic survey results once a risk of Down syndrome has been established in the first trimester.

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