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- Title
Prolonged duration of persistent cell-free fetal DNA from vanishing twin.
- Authors
Niles, K. M.; Murji, A.; Chitayat, D.; Niles, Kirsten M; Murji, Ally; Chitayat, David
- Abstract
Cell free fetal DNA (cffDNA) based aneuploidy screening has provided a highly accurate, non-invasive screening test in pregnancy. Cumulatively, NIPT has an approximately 1% false positive rate. Cases of co-twin demise result in as much as 42.1% of confirmed false positive NIPT results. To date, the longest documented duration of time following ultrasound identification of first trimester co-twin demise resulting in sex chromosome discrepancy or false positive NIPT is 8 weeks. We report a false positive NIPT for fetal sex at 21+3 weeks gestation by cffDNA secondary to a vanishing twin identified at 6+1 weeks gestation, which subsequently resolved on retesting at 28+6 weeks gestation. This indicates a persistence of cffDNA from the vanished twin for at least 15 weeks. In cases of known vanishing twin syndrome, it is important to be aware of the potential for discordant results secondary to the demised twin including second trimester testing prompted by anatomical findings, even when it co-twin demise occurs in early gestation.
- Subjects
ANEUPLOIDY; PLOIDY; NONDISJUNCTION (Genetics); PREGNANCY; CHROMOSOME analysis; FERTILIZATION in vitro
- Publication
Ultrasound in Obstetrics & Gynecology, 2018, Vol 52, Issue 4, p547
- ISSN
0960-7692
- Publication type
case study
- DOI
10.1002/uog.19004