BACKGROUND AND PURPOSE:

• Bellai-dussault et al. (AJOG, 2023) assessed the association between a failed cell-free DNA (cfDNA) test and common aneuploidies

METHODS:

• Population-based retrospective cohort study
  • Data derived from the Better Outcomes Registry and Network (BORN) province-wide database in Ontario, Canada
• Population
  • All singleton pregnancies with cfDNA screening record
  • Delivered from September 2016 to March 2019
• Exposures
  • Failed cfDNA screen on first attempt
  • Successful cfDNA screen with low-risk result
• Study design
  • Modified Poisson regressions were used to determine relative risk (RR)
  • Adjustments: Funding status (publicly funded versus self-paid) | Gestational age at screening | Method of conception | Maternal age
• Primary outcome
  • Trisomies 21, 18, 13 and sex chromosome aneuploidies

RESULTS:

• 35,146 pregnancies underwent cfDNA screening
• Overall cfDNA screening failure rates
  • First attempt: 4.8%
  • Multiple attempts: 2.2%
• Abnormal cytogenetic results in patients with failed cfDNA screening: 19.4%
• Pregnancies with a failed cfDNA screen on first attempt had a higher risk for trisomies 21, 18, 13 vs successful, low-risk cfDNA screen results
  • RR 130.3 (95% CI, 64.7 to 262.6)
  • Risk difference: 5.4% (95% CI, 2.6 to 8.3)
• Risk for sex chromosome aneuploidies was not significantly greater in pregnancies with a failed result vs low-risk result
  • RR 2.7 (95% CI, 0.9 to 7.9)
  • Risk difference 1.2% (95% CI, –0.9 to 3.2)

CONCLUSION:

• Failed NIPS screens are fairly common at 5%
• Pregnancies with a failed first attempt are at a higher risk of trisomies 21, 18, and 13, but not sex chromosome aneuploidies
• The authors state

Further, a failed cfDNA screen is associated with an increased risk of chromosomal abnormalities, regardless of the number of attempts

This study provides valuable information for clinicians as well as policy makers who consider performance of cfDNA screening in prenatal screening programs

Learn More – Primary Sources:

Cytogenetic outcomes following a failed cell-free DNA screen: a population-based retrospective cohort study of 35,146 singleton pregnancies

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