Classification of factors involved in nonreportable results of noninvasive prenatal testing (NIPT) and prediction of success rate of second NIPT.

Suzumori N1,2, Sekizawa A3, Takeda E1,2, Samura O4, Sasaki A5, Akaishi R5, Wada S5, Hamanoue H6, Hirahara F6, Kuriki H6, Sawai H7, Nakamura H8, Yamada T9, Miura K10, Masuzaki H10, Yamashita T11, Kamei Y12, Namba A12, Murotsuki J13, Tanemoto T4, Fukushima A14, Haino K15, Tairaku S16, Matsubara K17, Maeda K18, Kaji T19, Ogawa M20, Osada H21, Nishizawa H22, Okamoto Y23, Kanagawa T23, Kakigano A24, Endo M24, Kitagawa M25, Ogawa M26, Izumi S27, Katagiri Y28, Takeshita N28, Kasai Y29, Naruse K30, Neki R31, Masuyama H32, Hyodo M33, Kawano Y34, Ohba T35, Ichizuka K36, Nagamatsu T37, Watanabe A38, Nishikawa N39, Hamajima N39, Shirato N3, Yotsumoto J40, Nishiyama M5, Koide K3, Hirose T3, Sago H5.

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Abstract

OBJECTIVE:

To evaluate the reasons for nonreportable cell-free DNA (cfDNA) results in noninvasive prenatal testing (NIPT), we retrospectively studied maternal characteristics and other details associated with the results.

METHODS:

A multicenter retrospective cohort study in pregnant women undergoing NIPT by massively parallel sequencing (MPS) with failed cfDNA tests was performed between April 2013 and March 2017. The women's data and MPS results were analyzed in terms of maternal characteristics, test performance, fetal fraction, z-scores, anticoagulation therapy, and other details of the nonreportable cases.

RESULTS:

Overall, 110 (0.32%) of 34,626 pregnant women had nonreportable cfDNA test results after an initial blood sampling; 22 (20.0%) cases had a low fetal fraction (<4%), and 18 (16.4%) cases including those with a maternal malignancy, were found to have altered genomic profile. Approximately half of the cases with nonreportable results had borderline z-score. Among the women with nonreportable results because of altered genomic profile, the success rate of retesting using a second blood sampling was relatively low (25.0%-33.3%). Thirteen (11.8%) of the women with nonreportable results had required hypodermic heparin injection.

CONCLUSIONS:

The classification of nonreportable results using cfDNA analysis is important to provide women with precise information and to reduce anxiety during pregnancy.