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ICD-10-CM 2027 diagnosis code

K55.021Focal (segmental) acute infarction of small intestine

✓ Billable / specificMCC — major complication/comorbidity

K55.021 is a valid, billable ICD-10-CM code for focal (segmental) acute infarction of small intestine. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2017 (effective October 1, 2016). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About K55.021

K55.021 is the ICD-10-CM diagnosis code for focal (segmental) acute infarction of small intestine. It belongs to category K55 (vascular disorders of intestine), block K55-K64 (other diseases of intestines) and chapter 11 (diseases of the digestive system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within K55.02 (acute infarction of small intestine), K55.021 is specifically for focal (segmental) acute infarction of small intestine. Related codes cover diffuse acute infarction of small intestine (K55.022) and extent unspecified (K55.029).

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" 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 393 (Other Digestive System Diagnoses with MCC, relative weight 1.5881), DRG 394 (Other Digestive System Diagnoses with CC, relative weight 0.9228), DRG 395 (Other Digestive System Diagnoses without CC/MCC, relative weight 0.6382), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), in MDC 06 (Diseases and Disorders of the Digestive System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), 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 was added in FY2017, effective October 1, 2016.

Before ICD-10, this condition was coded in ICD-9-CM as 557.0 (acute vascular insufficiency of intestine).

Notes that apply from higher levels

Instructions written at a parent level also apply to K55.021.

› From K55 Vascular disorders of intestine
Excludes1
  • necrotizing enterocolitis of newborn (P77.-)
Excludes2
  • angioectasia (angiodysplasia) duodenum (K31.81-)

Broader instructions also apply from Chapter 11: Diseases of the digestive system.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to K55.021.

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 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

MDC 15 · Newborns and Other Neonates with Conditions Originating in the Perinatal Period

ICD-9-CM equivalent

Converter →
  • 557.0Acute vascular insufficiency of intestineapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2017 (effective 10/1/2016): Added
  • No changes since FY2017.

Common questions about K55.021

Is K55.021 billable?

Yes. K55.021 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can K55.021 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict K55.021 as a principal diagnosis.

Is K55.021 a CC or MCC?

K55.021 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does K55.021 group to?

K55.021 is used in the MS-DRG v44.0 logic for MS-DRG 393 (Other Digestive System Diagnoses with MCC), MS-DRG 394 (Other Digestive System Diagnoses with CC), MS-DRG 395 (Other Digestive System Diagnoses without CC/MCC), MS-DRG 791 (Prematurity with Major Problems) and MS-DRG 793 (Full Term Neonate with Major Problems). 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 K55.021?

The CMS General Equivalence Mappings map K55.021 to ICD-9-CM 557.0.