ICD-10-CM Diagnosis Code I80.9 - Phlebitis and thrombophlebitis of unspecified site (original) (raw)

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ICD List 2025-2026 Edition

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Phlebitis and thrombophlebitis of unspecified site

ICD-10-CM Code:

I80.9

ICD-10 Code for:

Phlebitis and thrombophlebitis of unspecified site

Is Billable?

Yes - Valid for Submission

Chronic Condition Indicator: [1]

Not chronic

Code Navigator:

I80.9 is a billable diagnosis code used to specify a medical diagnosis of phlebitis and thrombophlebitis of unspecified site. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2025 through September 30, 2026.

Unspecified diagnosis codes like I80.9 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

  1. Code Information
  2. Approximate Synonyms
  3. Clinical Classification
  4. Clinical Information
  5. Tabular List of Diseases and Injuries
  6. Index to Diseases and Injuries References
  8. Diagnostic Related Groups Mapping
  9. Convert to ICD-9 Code
  10. Patient Education
  11. Other Codes Used Similar Conditions
  12. Code History

The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

CCSR Code: CIR033

Inpatient Default: Y - Yes, default inpatient assignment for principal diagnosis or first-listed diagnosis.

Outpatient Default: Y - Yes, default outpatient assignment for principal diagnosis or first-listed diagnosis.

formation or presence of a blood clot (thrombus) in the cavernous sinus of the brain. infections of the paranasal sinuses and adjacent structures, craniocerebral trauma, and thrombophilia are associated conditions. clinical manifestations include dysfunction of cranial nerves iii, iv, v, and vi, marked periorbital swelling, chemosis, fever, and visual loss. (from adams et al., principles of neurology, 6th ed, p711)

formation or presence of a blood clot (thrombus) in the lateral sinuses. this condition is often associated with ear infections (otitis media or mastoiditis) without antibiotic treatment. in developed nations, lateral sinus thrombosis can result from craniocerebral trauma; brain neoplasms; neurosurgical procedures; thrombophilia; and other conditions. clinical features include headache; vertigo; and increased intracranial pressure.

inflammation of a vein, often a vein in the leg. phlebitis associated with a blood clot is called (thrombophlebitis).

formation or presence of a blood clot (thrombus) in the superior sagittal sinus or the inferior sagittal sinus. sagittal sinus thrombosis can result from infections, hematological disorders, craniocerebral trauma; and neurosurgical procedures. clinical features are primarily related to the increased intracranial pressure causing headache; nausea; and vomiting. severe cases can evolve to seizures or coma.

formation or presence of a blood clot (thrombus) in the cranial sinuses, large endothelium-lined venous channels situated within the skull. intracranial sinuses, also called cranial venous sinuses, include the superior sagittal, cavernous, lateral, petrous sinuses, and many others. cranial sinus thrombosis can lead to severe headache; seizure; and other neurological defects.

inflammation of a vein associated with a blood clot (thrombus).

References found for this diagnosis code in the External Cause of Injuries Index:

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

ICD-9-CM: 451.9

This is a direct match with no additional mapping qualifiers. The absence of a flag generally means the mapping is considered exact or precise. In other words, the ICD-10 code maps cleanly to the ICD-9 code without qualification, approximation, or needing multiple codes.