What should be done when a non‑invasive prenatal test (NIPT) yields no result because of limitations of the testing algorithm?

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Last updated: May 11, 2026 • View editorial policy

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When NIPT Yields No Result Due to Testing Algorithm Limitations

When NIPT fails to provide a result, offer genetic counseling immediately and provide the option of invasive diagnostic testing (CVS or amniocentesis), as failed NIPT is associated with increased risk of fetal aneuploidy and other chromosomal abnormalities.

Understanding NIPT Failure

NIPT failure occurs in approximately 1.6-6.4% of cases depending on the testing platform, with massive parallel sequencing having the lowest failure rate (1.58%) and SNP-based methods having the highest (6.39%) 1. The ACMG guidelines explicitly recognize that technical issues including low fetal fraction are sources of discordant or failed NIPT results 2.

Why Failed NIPT Matters

Failed NIPT is not simply a technical inconvenience—it carries clinical significance:

  • Increased aneuploidy risk: Recent evidence demonstrates that patients receiving "no call" results are at elevated risk for chromosomal abnormalities 1
  • Detection of missed abnormalities: Failed NIPT contributes to detection of chromosomal anomalies that NIPT cannot identify, accounting for approximately 9% of cases with structural abnormalities or microdeletions 3

Immediate Management Algorithm

Step 1: Attempt Retesting (If Appropriate)

  • Retest success rate: 85.9-95.8% of failed cases obtain valid results on second attempt 4, 5
  • When to retest: If gestational age allows and fetal fraction was the issue
  • Timing consideration: Success increases with advancing gestational age, but delays definitive diagnosis 4

Step 2: Genetic Counseling (Mandatory)

Professional societies recommend that patients with failed NIPT receive genetic counseling by a genetics professional 2. This counseling should address:

  • The increased risk of aneuploidy associated with test failure
  • Limitations of NIPT as a screening (not diagnostic) test
  • Options for invasive diagnostic testing
  • The fact that NIPT analyzes placental, not fetal, DNA

Step 3: Offer Invasive Diagnostic Testing

Recommend diagnostic testing via:

  • CVS (if <15-16 weeks gestation)
  • Amniocentesis (if ≥15 weeks gestation)

The diagnostic test should be chromosomal microarray (CMA) rather than standard karyotype alone, as this detects:

  • Common aneuploidies (trisomies 13,18,21)
  • Sex chromosome abnormalities
  • Microdeletions/microduplications (which NIPT cannot detect)
  • Copy number variants

Step 4: Enhanced Ultrasound Surveillance

Even if the patient declines invasive testing, implement:

  • Detailed anatomical survey at 18-20 weeks
  • Serial growth assessments (early growth restriction detected 37% of missed chromosomal abnormalities 3)
  • First-trimester nuchal translucency if still early enough (though only detects ~10% of microdeletions 3)

Common Pitfalls to Avoid

  1. Do not reassure patients that failed NIPT is "just technical": The failure itself indicates increased risk 1

  2. Do not simply repeat NIPT indefinitely: After one failed retest, proceed to diagnostic testing rather than continuing screening attempts 4

  3. Do not rely on nuchal translucency alone: Approximately 90% of chromosomal anomalies missed by NIPT had normal NT measurements 3

  4. Do not assume normal outcome without follow-up: Among failed NIPT cases, 54.5% with high total free DNA content required midterm termination, significantly higher than those with low fetal fraction (17.6%) 5

Additional Risk Factors to Assess

When NIPT fails, evaluate for associated findings that increase chromosomal abnormality risk:

  • Low PAPP-A (contributed to 12% of detected abnormalities 3)
  • Structural anomalies on ultrasound (51% of missed cases 3)
  • Early fetal growth restriction (37% of missed cases 3)
  • Maternal factors: obesity, multiple gestation, maternal malignancy (can cause false results 2)

Documentation and Communication

Clearly document:

  • The failed NIPT result and reason (low fetal fraction, technical failure, etc.)
  • Genetic counseling provided
  • Options discussed (retest, invasive testing, enhanced surveillance)
  • Patient's informed decision

The key principle: Failed NIPT is not a neutral result—it represents a positive indication for further evaluation through either retesting with immediate progression to diagnostic testing if unsuccessful, or proceeding directly to invasive testing based on gestational age and clinical context 4, 1.

References

4
Research

[Factors affecting the failure of non-invasive prenatal testing and the feasibility analysis of retesting].

Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics, 2020

5
Research

[Preliminary analysis of the cause for the failure of non-invasive prenatal testing using cell-free fetal DNA derived from peripheral maternal blood].

Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics, 2018

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.