Reasons for failure of noninvasive prenatal test for cell-free fetal DNA in maternal peripheral blood.

BACKGROUND

To explore reasons for the failure of noninvasive prenatal test (NIPT) for cell-free fetal DNA (cffDNA) in maternal peripheral blood, and discuss appropriate treatment schemes after the failure of the test.

METHODS

Altogether 41,136 pregnant women participated in NIPT. Blood samples were taken again from pregnant women who failed the first blood collection upon their informed consent. Prenatal genetic counseling or prenatal diagnosis was recommended for pregnant women with final NIPT failure.

RESULTS

The first failure rate of NIPT was 0.737% (303/41136), and the reason for the failure was the low ratio of cffDNA in 135 (44.6%) of the 303 pregnant women. After the second or third blood sampling, the final failure rate was 0.182% (75/41136). The low ratio of cffDNA was the main reason for test failure in 42 (56.0%) of the 75 pregnant women who finally failed NIPT, among whom 44 (58.7%) had underlying diseases, including 21 (47.7%) with more than two coexisting underlying diseases. Only 27 (36.0%) of the 75 pregnant women with NIPT failure underwent interventional prenatal diagnosis.

CONCLUSIONS

The main reason for NIPT failure was the low ratio of cffDNA. Postponing the gestational weeks of blood collection may improve the success rate. Resampling and retesting upon informed consent in pregnant women who failed the first test could improve the success rate. For pregnant women who finally failed NIPT, it is suggested strengthening the genetic counseling, prenatal examination, and ultrasound evaluation, and carry out interventional prenatal diagnosis if necessary.