Table 2 Common trisomies and fetal sex test results from participating laboratories in the 2018 NIPT Educational Survey.

From: Assessment of laboratories offering cell-free (cf) DNA screening for Down syndrome: results of the 2018 College of American Pathology External Educational Exercises

Sample

FF Acceptable?

 

Chromosome 21

Chromosome 18

Chromosome 13

Fetal sex

NIPT-

Yes

No

Miss

 

Neg

Pos

Fail

Err

Neg

Pos

Fail

Err

Neg

Pos

Fail

Err

M

F

NR

Err

01

41

0

0

 

41

0

0

0

41

0

0

0

41

0

0

0

32

0

9

0

02

41

0

0

 

1a

40

0

0

41

0

0

0

41

0

0

0

16b

16b

9

0

03

41

0

0

 

41

0

0

0

41

0

0

0

41

0

0

0

0

32

9

0

Sum

123

0

0

 

83a

40

0

0

123

0

0

0

123

0

0

0

48

48

18

0

04

46

3c

2

 

47

0

4c

0

47

0

4c

0

47

0

4c

0

0

39

13c

0

05

51

0

0

 

50

0

1d

0

50

0

1d

0

50

0

1d

0

25b

16b

10

0

06

48

1

2

 

46

0

5e

0

46

0

5e

0

46

0

5e

0

20b,f

19b

12

0

Sum

145

4

4

 

143

0

10

0

143

0

10

0

143

0

10

0

45

74

35

0

Total

268

4

4

0

226

40

10

0

266

0

10

0

266

0

10

0

92

122

53

0

  1. Err error, F female, Fail test failure/no call, FF fetal fraction, M male, Miss missing response, Neg screen negative, NIPT noninvasive prenatal testing, NR do not report/interpret or missing, Pos screen positive.
  2. aThis participant received a normal sample for NIPTA-02.
  3. bThese challenges had lots with male fetuses and other lots with female fetuses.
  4. cThree participants received the same lot and all had lower than expected fetal fractions; the fourth reported a fetal fraction of 18%.
  5. dThis laboratory reported an acceptable fetal fraction of 5.6% but the test failed for other reasons.
  6. eThree of the five reported acceptable fetal fractions (range 5.6% to 9.9%); no further information on reasons for the failures. The failures came from four separate lots.
  7. fOne male was reported as 47,XXY. That lot had two participants and the other called it a normal male.