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Saturday, July 19, 2014

Trailers (88): Non-invasive prenatal testing

Pergament et al. Single-nucleotide polymorphism-based noninvasive prenatal screening in a high-risk and low-risk cohort

Why should you read about this topic?

Because noninvasive prenatal screening is one of the most rapidly evolving areas of our specialty.  Try to keep up.

What were the authors trying to do?

Measure the performance of a single-nucleotide polymorphism-based noninvasive test for fetal aneuploidy in high-risk and low-risk groups

Who participated and in what setting?

Women (N=1064) with a singleton pregnancy at least 7 weeks gestational age at 36 prenatal care centers

What was the study design?

Retrospective cohort study of cell-free DNA analyzed using a single-nucleotide polymorphism-based algorithm

What were the main outcome measures?

Trisomy 21, 18, 13, or monosomy X, euploid, and male or female

What were the results?

8.1% did not generate a cell-free fetal DNA result (no-calls).  Excluding no-calls, triploidy, sex chromosome abnormalities, and fetal mosaicism, sensitivity was 100% for trisomy 21, 13, and sex, 96% for trisomy 18, and 90% for monosomy X.  Specificity was 100% for trisomies 21 and 13 and 99.9% for trisomy 18 and monosomy X.  Test performance was not different between high-risk and low-risk groups. Fetal sex was correctly identified in all cases (excluding no-calls).

What is the most interesting image in the paper?

Table 2

What were the study strengths and weaknesses?

Strengths: analysis for aneuploidy in no-calls.  Weaknesses: no adjustment for maternal weight

What does the study contribute for your practice?

Another option for non-invasive fetal aneuploidy testing