Open AccessSequential combined test, second trimester maternal serum markers, and circulating fetal cells to select women for invasive prenatal diagnosis
Author(s) -
Paolo Guanciali Franchi,
Chiara Palka,
Elisena Morizio,
Giulia Sabbatinelli,
Melissa Alfonsi,
Donatella Fantasia,
G Sitar,
Peter Benn,
Giuseppe Calabrese
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0189235
Subject(s) - medicine , fetus , prenatal diagnosis , obstetrics , odds ratio , pregnancy , false positive rate , prenatal screening , cell free fetal dna , gynecology , biology , genetics , statistics , mathematics
From January 1 st 2013 to August 31 st 2016, 24408 pregnant women received the first trimester Combined test and contingently offered second trimester maternal serum screening to identify those women who would most benefit from invasive prenatal diagnosis (IPD). The screening was based on first trimester cut-offs of ≥1:30 (IPD indicated), 1:31 to 1:899 (second trimester screening indicated) and ≤1:900 (no further action), and a second trimester cut-off of ≥1:250. From January 2014, analysis of fetal cells from peripheral maternal blood was also offered to women with positive screening results. For fetal Down syndrome, the overall detection rate was 96.8% for a false-positive rate of 2.8% resulting in an odds of being affected given a positive result (OAPR) of 1:11, equivalent to a positive predictive value (PPV) of 8.1%. Additional chromosome abnormalities were also identified resulting in an OAPR for any chromosome abnormality of 1:6.6 (PPV 11.9%). For a sub-set of cases with positive contingent test results, FISH analysis of circulating fetal cells in maternal circulation identified 7 abnormal and 39 as normal cases with 100% specificity and 100% sensitivity. We conclude that contingent screening using conventional Combined and second trimester screening tests is effective but can potentially be considerably enhanced through the addition of fetal cell analysis.