ICD-10-CM 2027 diagnosis code
B66.3Fascioliasis
B66.3 is a valid, billable ICD-10-CM code for fascioliasis. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Fascioliasis, ICD-10 code for Distoma hepaticum infestation.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About B66.3
B66.3 is the ICD-10-CM diagnosis code for Fascioliasis. It belongs to category B66 (other fluke infections), block B65-B83 (helminthiases) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within B66 (other fluke infections), B66.3 is specifically for Fascioliasis. Related codes cover Opisthorchiasis (B66.0), Clonorchiasis (B66.1), Dicroceliasis (B66.2), Paragonimiasis (B66.4), Fasciolopsiasis (B66.5), other specified fluke infections (B66.8) and fluke infection, unspecified (B66.9).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 441 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with MCC, relative weight 1.8219), DRG 442 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with CC, relative weight 0.9602) and DRG 443 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis without CC/MCC, relative weight 0.6885), in MDC 07 (Diseases and Disorders of the Hepatobiliary System and Pancreas), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 121.3 (Fascioliasis).
Coding notes
- Infection due to Fasciola gigantica
- Infection due to Fasciola hepatica
- Infection due to Fasciola indica
- Sheep liver fluke disease
Notes that apply from higher levels
Instructions written at a parent level also apply to B66.3.
Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.
Alphabetic index entries
14 entriesTerms in the official ICD-10-CM index that lead to B66.3.
- Cirrhosis, cirrhotic (hepatic) (liver) › biliary (cholangiolitic) (cholangitic) (hypertrophic) (obstructive) (pericholangiolitic) › due to › flukes
- Disease, diseased › liver (chronic) (organic) › fluke › sheep
- Distoma hepaticum infestation
- Distomiasis › bile passages
- Distomiasis › hepatic
- Distomiasis › liver
- Fascioliasis
- Flukes NEC › liver
- Infection, infected, infective (opportunistic) › Fasciola (gigantica) (hepatica) (indica)
- Infection, infected, infective (opportunistic) › sheep liver fluke
- Infestation › Distoma hepaticum
- Infestation › Fasciola (gigantica) (hepatica) (indica)
- Infestation › fluke › liver (sheep)
- Infestation › fluke › sheep liver
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 07 · Diseases and Disorders of the Hepatobiliary System and Pancreas
ICD-9-CM equivalent
Converter →- 121.3Fascioliasisexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about B66.3
Is B66.3 billable?
- Yes. B66.3 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can B66.3 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict B66.3 as a principal diagnosis.
Is B66.3 a CC or MCC?
- B66.3 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does B66.3 group to?
- B66.3 is used in the MS-DRG v44.0 logic for MS-DRG 441 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with MCC), MS-DRG 442 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis with CC) and MS-DRG 443 (Disorders of Liver Except Malignancy, Cirrhosis or Alcoholic Hepatitis without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for B66.3?
- The CMS General Equivalence Mappings map B66.3 to ICD-9-CM 121.3.