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  6. 2025 ICD-10-CM Code I81

2025 ICD-10-CM Diagnosis Code I81

Portal vein thrombosis

ICD-10-CM Code:
I81
ICD-10 Code for:
Portal vein thrombosis
Is Billable?
Yes - Valid for Submission
Chronic Condition Indicator: [1]
Not chronic
Code Navigator:

I81 is a billable diagnosis code used to specify a medical diagnosis of portal vein thrombosis. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2024 through September 30, 2025.

Code Classification

  • Diseases of the circulatory system
    I00–I99
    • Diseases of veins, lymphatic vessels and lymph nodes, not elsewhere classified
      I80-I89
      • Portal vein thrombosis
        I81

Approximate Synonyms

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.

  • Acute GIT vascular insufficiency
  • Acute ischemia of colon due to thrombosis of mesenteric vein
  • Acute occlusion of mesenteric vein
  • Acute thrombosis of mesenteric vein
  • Acute thrombosis of mesenteric vein
  • Acute vascular insufficiency of intestine
  • Acute visceral ischemia
  • Chronic thrombosis of mesenteric vein
  • Obstruction of visceral vein
  • Obstruction of visceral vein
  • Portal vein obstruction
  • Portal vein thrombosis
  • Thrombosis of mesenteric vein
  • Thrombosis of mesenteric vein
  • Thrombosis of mesenteric vein
  • Visceral ischemia

Clinical 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.

Acute phlebitis; thrombophlebitis and thromboembolism

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.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


Inclusion Terms

Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
  • Portal (vein) obstruction

Type 2 Excludes

Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
  • hepatic vein thrombosis I82.0
  • phlebitis of portal vein K75.1

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Convert I81 to ICD-9-CM

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.

Portal vein thrombosis

ICD-9-CM: 452

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.

View Conversion

Patient Education


Deep Vein Thrombosis

Deep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Most deep vein clots occur in the lower leg or thigh. If the vein swells, the condition is called thrombophlebitis. A deep vein thrombosis can break loose and cause a serious problem in the lung, called a pulmonary embolism.

Sitting still for a long time can make you more likely to get a DVT. Some medicines and disorders that increase your risk for blood clots can also lead to DVTs. Common symptoms are :

  • Warmth and tenderness over the vein
  • Pain or swelling in the part of the body affected
  • Skin redness

Treatment includes medicines to ease pain and inflammation, break up clots and keep new clots from forming. Keeping the affected area raised and applying moist heat can also help. If you are taking a long car or plane trip, take a break, walk or stretch your legs and drink plenty of liquids.


[Learn More in MedlinePlus]

Liver Diseases

Your liver is the largest organ inside your body. It helps your body digest food, store energy, and remove poisons.

There are many kinds of liver diseases:

  • Diseases caused by viruses, such as hepatitis A, hepatitis B, and hepatitis C
  • Diseases caused by drugs, poisons, or too much alcohol. Examples include fatty liver disease and cirrhosis.
  • Liver cancer
  • Inherited diseases, such as hemochromatosis and Wilson disease

Symptoms of liver disease can vary, but they often include swelling of the abdomen and legs, bruising easily, changes in the color of your stool and urine, and jaundice, or yellowing of the skin and eyes. Sometimes there are no symptoms. Tests such as imaging tests and liver function tests can check for liver damage and help to diagnose liver diseases.


[Learn More in MedlinePlus]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.