BACKGROUND AND PURPOSE:

• Gil et al. (Ultrasound in Obstetrics & Gynecology, 2019) assessed the performance of NIPS for twin pregnancies

METHODS:

• Prospective study and systematic review and meta-analysis
• Prospective study
  • Twin pregnancies between 10w0d and 14w1d
  • Screened for trisomies 21, 18 and 13 using DANSR NIPS technology
• NIPS performed after routine first-trimester combined testing
• Systematic review and meta-analysis
  • Peer-reviewed publications
  • Clinical validation or implementation studies that assessed maternal cfDNA testing for trisomies 21, 18 and 13 in twin pregnancy
  • Technology included massively parallel shotgun sequencing or targeted analysis (either by NGS or custom microarray)

RESULTS:

Prospective study

• 997 twin pregnancies
• NIPS correctly classified
  • Trisomy 21: 94.1% (16/17 cases)
  • Trisomy 18: 90.0% (9/10 cases)
  • Trisomy 13: 50.0% (1/2 cases)
  • True negatives (none of the 3 trisomies): 99.4% (962/968 cases)

Meta-Analysis

• Above data combined with 7 studies from the literature
• Trisomy 21 detection meta-analysis
  • 56 trisomy 21 | 3718 non-trisomy 21 twin pregnancies
  • Pooled weighted detection rate (DR): 98.2% (95% CI, 83.2–99.8%)
  • FPR 0.05% (95% CI, 0.01–0.26%)
• Trisomy 18 detection meta-analysis
  • 18 trisomy 18 and 3143 non-trisomy 18 twin pregnancies
  • The pooled weighted DR: 88.9% (95% CI, 64.8–97.2%)
  • FPR 0.03% (95% CI, 0.00–0.33%)
• Trisomy 13 detection meta-analysis
  • There were only three affected cases
  • Two (66.7%) were detected | FPR of 0.19% (5/2569)

CONCLUSION:

• NIPS in twins
  • Trisomy 21 performance is similar to singleton pregnancy
  • Trisomy 21 performance is superior to first-trimester combined test or second-trimester biochemical testing
• The authors note that due to small ‘n’ for trisomies 13 and 18, accurate assessment is limited

Learn More – Primary Sources:

Screening for trisomies by cfDNA testing of maternal blood in twin pregnancy: update of The Fetal Medicine Foundation results and meta‐analysis

Related ObG Topics:

cfDNA vs. Routine Screening – How Do They Compare?

What is the Best Strategy for Fetal Aneuploidy Screening?

Does cfDNA in First Trimester Signal Subsequent Preeclampsia?