Combined first-trimester screening most effective for testing foetal down syndrome
24 Jun 2020
It was speculated that the family’s wish for a second child in a short period of time might be the reason why they allegedly refused permission for a C-section delivery.Combined first-trimester screening (CFTS) appears to be the best traditional method for the diagnosis of foetal down syndrome, a recent study has found.
Of the 21,713 pregnant mothers who underwent CFTS, 370 (1.7 percent), 732 (3.37 percent), and 20,611 (94.92 percent) were classified as high, intermediate, and low risk, respectively. In comparison, the number of participants who underwent double, triple, and quadruple screening was 68,512, 13,692, and 8,087, respectively.
CFTS yielded the smallest proportion of high- and intermediate-risk mothers, as compared to the other traditional testing methods (p<0.01).
Despite this, the detection rate for high-risk patients was highest in CFTS (78.79 percent), as opposed to the quadruple, triple, and double screening (72.73 percent, 69.23 percent, and 70.0 percent, respectively). The discrepancy, however, was only nominal (p=0.829).
At a high-risk cut-off of 1:270, CFTS demonstrated a true negative rate of 98.41 percent, higher than that in the quadruple (96.31 percent), triple (97.09 percent), and double (94.76 percent) screenings. Conversely, the false positive rate in CFTS was lower than in the other methods (1.59 percent vs 3.69 percent, 2.91 percent, and 5.24 percent, respectively).
The positive predictive rate of CFTS was likewise superior.
“Our study demonstrated if only one traditional screening test is allowed to screen pregnant women, CFTS is recommended as the first choice. CFTS can reduce the number of noninvasive prenatal screenings, thus reducing the cost of health economics,” the researchers said.