Outcomes of non-invasive prenatal testing over an 8-year period at Nippon Medical School Hospital

Abstract

Background

Non-invasive prenatal testing (NIPT) is a screening test for fetal chromosomal abnormalities, such as fetal aneuploidy, and has been offered at our hospital since 2013. We aimed to assess whether applicants for NIPT could be given more accurate information regarding NIPT outcomes after assessing the data from our center.

Methods

This retrospective observational study included 819 pregnant women who requested NIPT at Nippon Medical School Hospital from November 2013 to October 2021. We examined data on NIPT results and clinical outcomes from medical records.

Results

Of the 819 women, 764 (93.2%) underwent NIPT, and 55 (6.7%) did not. Of the 764 women who underwent NIPT, there were 17 with positive results (2.2%), of whom 2 (11.8%), 4 (23.5%), and 11 (64.7%) tested positive for trisomy 13, 18, and 21, respectively. The true-positive rates after definitive diagnoses of trisomy 13, 18, and 21 were 1 (50%), 3 (75%), and 11 (100%), respectively. Of the 17 positive results, there were two false-positives was (11.8%) (for trisomy 13 and trisomy 18). Eleven women with fetal aneuploidy terminated their pregnancies, and four cases resulted in intrauterine fetal demise. Two patients had undeterminable results from the first blood sampling, possibly due to unfractionated heparin treatment, and repeat tests after ceasing heparin treatment were negative.

Conclusions

Our results were generally similar to nationwide data of Japan. Providers for NIPT can give more detailed and individualized genetic counseling for each situation if the data of their facility is taken into account.