2027 ICD-10-CM Diagnosis Code I81Portal vein thrombosis
ICD-10-CM Codes›I00–I99›I80-I89›I81
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
I81 is a billable ICD-10-CM diagnosis code for portal vein thrombosis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 441 through 443. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 202 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acute phlebitis; thrombophlebitis and thromboembolism.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute ischemia of colon due to thrombosis of mesenteric vein
- Acute occlusion 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
- Portal vein obstruction
- Portal vein thrombosis
- Thrombosis of mesenteric vein
- Visceral ischemia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I81: its own notes plus those printed at Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Portal (vein) obstruction
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name I81, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Pseudoangioma I81
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Portal Vein Thrombosis
the formation of a blood clot (thrombus) in the portal vein.
Patient EducationClinical
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.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I81 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I81Overview
What is the ICD-10 code for portal vein thrombosis?
The ICD-10-CM code for portal vein thrombosis is I81. It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I81 (Portal vein thrombosis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report portal vein thrombosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I81 group to?
When portal vein thrombosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 442, 441, 443, with relative weights from 0.6890 to 1.8226 depending on complications. Higher weights mean higher Medicare reimbursement.
Is I81 a CC or MCC?
CMS lists I81 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 202 closely related codes in its exclusion list.
What is the ICD-9 equivalent of I81?
Under the General Equivalence Mappings, portal vein thrombosis converts to ICD-9-CM 452 (portal vein thrombosis). The mapping is a direct match.
