2027 ICD-10-CM Diagnosis Code K55.1Chronic vascular disorders of intestine

ICD-10-CM Codes›K00–K95›K55-K64›K55

ICD-10-CM K55.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

K55.1 is a billable ICD-10-CM diagnosis code for chronic vascular disorders of intestine. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 393 through 395. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 25 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified and unspecified gastrointestinal disorders and Peripheral and visceral vascular disease.

K55.1 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 108 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 108, ESRD (V21) category 108, and ESRD (V24) category 108 for payment year 2027.

Code Identity

ICD-10-CM Code
K55.1
Billable Status
Yes — Valid for Submission
Code Describes
Chronic vascular disorders of intestine
Short Description
Chronic vascular disorders of intestine
Same as the full description in the CMS dataset.
Parent Code
K55
Vascular disorders of intestine

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK55-K64Other diseases of intestines
CategoryK55Vascular disorders of intestine
This CodeK55.1Chronic vascular disorders of intestine

Medicare Risk Adjustment (HCC)Billing

K55.1 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 108
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 108 · ESRD (V21): HCC 108 · ESRD (V24): HCC 108
ESRD V21 weights: 0.065 dialysis, 0.086–0.271 functioning graft · ESRD V24 weights: 0.073 dialysis, 0.074–0.287 functioning graft
Part D (RxHCC)
Not mapped
K55.1 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abdominal angina
  • Atherosclerosis of abdominal visceral artery
  • Atherosclerosis of superior mesenteric artery
  • Chronic gastrointestinal tract vascular insufficiency
  • Chronic inflammatory small bowel disease
  • Chronic ischemic colitis
  • Chronic ischemic enteritis
  • Chronic ischemic enterocolitis
  • Chronic vascular insufficiency
  • Chronic vascular insufficiency of intestine
  • Insufficiency of mesenteric artery
  • Ischemic enterocolitis
  • Ischemic stricture of intestine
  • Noninfective enteritis and colitis
  • Non-occlusive mesenteric ischemia
  • Stenosis of inferior mesenteric artery
  • Stenosis of mesenteric artery

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to K55.1: its own notes plus those printed at K55 and Chapter 11. 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.

  • Chronic ischemic colitis
  • Chronic ischemic enteritis
  • Chronic ischemic enterocolitis
  • Ischemic stricture of intestine
  • Mesenteric atherosclerosis
  • Mesenteric vascular insufficiency

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From K55 Vascular disorders of intestine applies to 27 codes
  • necrotizing enterocolitis of newborn (P77.-)

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.

From K55 Vascular disorders of intestine applies to 27 codes
  • angioectasia (angiodysplasia) duodenum (K31.81-)
From Chapter 11 (K00-K95) Diseases of the digestive system applies to 863 codes
  • 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)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name K55.1, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming K55.1: they are not reported together with it, unless the two conditions are unrelated.

  • K56 Paralytic ileus and intestinal obstruction without hernia
    ischemic stricture of intestine (K55.1)

Excludes2 1

These codes carry an Excludes2 note naming K55.1: its condition is not part of those codes, and both may be reported when the patient has both.

  • I70 Atherosclerosis
    mesenteric atherosclerosis (K55.1)

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR DIG025
Other specified and unspecified gastrointestinal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR CIR026
Peripheral and visceral vascular disease
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Intestinal Vascular Disorder

    a non-neoplastic or neoplastic vascular disorder that affects the intestines.

Patient EducationClinical

Digestive Diseases

When you eat, your body breaks food down to a form it can use to build and nourish cells and provide energy. This process is called digestion.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert K55.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
557.1 Chr vasc insuff intest
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About K55.1Overview

What is the ICD-10 code for chronic vascular disorders of intestine?

The ICD-10-CM code for chronic vascular disorders of intestine is K55.1 (sometimes written as K551). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is K55.1 (Vascular disorders of intestine) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report chronic vascular disorders of intestine on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does K55.1 group to?

When chronic vascular disorders of intestine is the principal diagnosis on an inpatient stay, it groups to MS-DRG 394, 395, 393, with relative weights from 0.6379 to 1.5877 depending on complications. Higher weights mean higher Medicare reimbursement.

Is K55.1 a CC or MCC?

CMS lists K55.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 25 closely related codes in its exclusion list.

Can K55.1 be reported with a code from P77?

Not as a rule. The Excludes1 note at K55, which applies to K55.1, lists "necrotizing enterocolitis of newborn (P77.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

Does K55.1 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. K55.1 mapped to HCC 108 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 108 (Vascular Disease), ESRD (V21) category 108 (Vascular Disease), and ESRD (V24) category 108 (Vascular Disease).