ICD-10 Code I81 – Portal vein thrombosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I81 – Portal vein thrombosis
What it is
Portal vein thrombosis means a blood clot is blocking the portal vein, which carries blood from the intestines to the liver. Use this code when documentation identifies thrombosis of the portal vein.
Clinical signs
Clinical features vary; refer to documentation. Patients may have abdominal pain, fever, enlarged spleen, or signs of portal hypertension such as varices or ascites.
When to use this code
Use I81 when the provider documents portal vein thrombosis, whether acute or chronic, and the clot is the principal diagnosis or a relevant coexisting condition. It also applies when imaging or specialist notes confirm the diagnosis. If the record only mentions possible thrombosis, check documentation before coding.
Do not use for
Do not use this code for thrombosis in other abdominal veins or for portal vein obstruction without documented thrombosis. If the chart is unclear about the vessel involved, check documentation.
Coding tip
Confirm the exact vessel and whether the thrombosis is documented as portal vein involvement before assigning I81.