Table 2. Performance of non-invasive prenatal testing in detection of trisomies 21, 18, and 13.

Aneuploidies	Sensitivity, %	Specificity, %	PPV, %	NPV, %
Trisomy 21	100	99.9	98.3	100
	(57/57)	(997/998)	(57/58)	(997/997)
Trisomy 18	92.9	100	100	99.7
	(39/42)	(1,013/1,013)	(39/39)	(1,013/1,016)
Trisomy 13	100	99.9	90.0	100
	(9/9)	(1,045/1,046)	(9/10)	(1,045/1,045)
Total	97.2	99.8	98.1	99.7
	(105/108)	(945/947)	(105/107)	(945/948)

PPV = positive predictive value, NPV = negative predictive value.