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v1.0.0
ICD-10 Guide
ICD-10 CodesQ91.0

Q91.0

Billable

Trisomy 18, nonmosaicism (meiotic nondisjunction)

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/11/2025

Code Description

ICD-10 Q91.0 is a billable code used to indicate a diagnosis of trisomy 18, nonmosaicism (meiotic nondisjunction).

Key Diagnostic Point:

Trisomy 18, also known as Edwards syndrome, is a chromosomal abnormality characterized by the presence of an extra 18th chromosome due to meiotic nondisjunction. This condition leads to severe developmental delays and multiple congenital malformations. Infants with Trisomy 18 often present with a distinct set of physical features, including a small head (microcephaly), a prominent occiput, low-set ears, and clenched fists with overlapping fingers. Other common anomalies include congenital heart defects, kidney abnormalities, and gastrointestinal issues. The prognosis for infants with Trisomy 18 is poor, with many not surviving beyond the first year of life. Diagnosis is typically made through karyotyping, which confirms the presence of the extra chromosome. Genetic counseling is essential for families affected by this condition, as it provides information on recurrence risks and management options.

Code Complexity Analysis

Complexity Rating: High

High Complexity

Complexity Factors

  • Requires understanding of genetic terminology and chromosomal abnormalities.
  • Differentiation from other trisomies and congenital conditions.
  • Need for precise documentation of associated congenital anomalies.
  • Potential for co-morbid conditions that complicate coding.

Audit Risk Factors

  • Inaccurate documentation of associated congenital anomalies.
  • Failure to provide genetic counseling notes.
  • Misclassification of the condition as mosaic rather than nonmosaic.
  • Inadequate linkage between diagnosis and clinical findings.

Specialty Focus

Medical Specialties

Pediatrics

Documentation Requirements

Detailed clinical notes on physical examination findings, growth parameters, and developmental milestones.

Common Clinical Scenarios

Management of infants with Trisomy 18 in NICU, including feeding difficulties and respiratory support.

Billing Considerations

Attention to the psychosocial aspects of care for families, including end-of-life discussions.

Genetics

Documentation Requirements

Comprehensive genetic testing results, family history, and counseling session notes.

Common Clinical Scenarios

Prenatal diagnosis of Trisomy 18 through amniocentesis or chorionic villus sampling.

Billing Considerations

Understanding of recurrence risks and implications for future pregnancies.

Coding Guidelines

Inclusion Criteria

Use Q91.0 When
  • Follow ICD
  • CM guidelines for coding congenital conditions, ensuring accurate documentation of associated anomalies and clinical findings
  • Use additional codes to capture specific congenital defects when applicable

Exclusion Criteria

Do NOT use Q91.0 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

81228CPT Code

Chromosomal analysis, karyotype

Clinical Scenario

Used to confirm diagnosis of Trisomy 18.

Documentation Requirements

Document the indication for testing and results.

Specialty Considerations

Geneticists should ensure comprehensive family history is included.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of congenital conditions, improving the accuracy of data collection and reimbursement processes for conditions like Trisomy 18.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of congenital conditions, improving the accuracy of data collection and reimbursement processes for conditions like Trisomy 18.

Reimbursement & Billing Impact

reimbursement processes for conditions like Trisomy 18.

Resources

Clinical References

  • •
    National Down Syndrome Society
  • •
    Genetics Home Reference

Coding & Billing References

  • •
    National Down Syndrome Society
  • •
    Genetics Home Reference

Frequently Asked Questions

What is the prognosis for a child with Trisomy 18?

The prognosis for children with Trisomy 18 is generally poor, with many not surviving past the first year of life. Those who do survive often face significant developmental challenges and require ongoing medical care.

How is Trisomy 18 diagnosed?

Trisomy 18 is diagnosed through karyotyping, which analyzes the chromosomes in a sample of blood or tissue to confirm the presence of an extra 18th chromosome.