Maternal serum screening for fetal Down's syndrome, a retrospective study

Area of Science:

• Biochemistry
• Genetics
• Obstetrics

Background:

• Down syndrome screening involves biochemical markers in maternal serum.
• Accurate screening improves prenatal diagnosis and management.

Purpose of the Study:

• To assess the effectiveness of human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), and unconjugated estriol (uE3) in screening for Down syndrome.
• To compare the detection rates and amniocentesis rates using different marker combinations.

Main Methods:

• Retrospective analysis of serum samples from 18,600 pregnancies, including 32 with fetal Down syndrome.
• Measured maternal serum concentrations of hCG, AFP, and uE3.
• Calculated multiples of the median (MOM) and risk cut-offs.

Main Results:

• hCG alone yielded a 41% detection rate with a 5.3% amniocentesis rate.
• Combining hCG and AFP improved detection to 65% with a 5.5% amniocentesis rate at a 1:300 risk cut-off.
• uE3 demonstrated validity as a screening marker.

Conclusions:

• Combined screening with hCG and AFP significantly enhances Down syndrome detection rates.
• The choice of markers, patient demographics, risk calculation, and cut-off values influence screening efficacy.
• uE3 is a valuable addition to Down syndrome screening protocols.