2027 ICD-10-CM Diagnosis Code K91.850Pouchitis
ICD-10-CM Codes›K00–K95›K90-K95›K91
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 463
- Not Chronic
K91.850 is a billable ICD-10-CM diagnosis code for pouchitis. 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, 791, 793. 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 70 closely related codes. Coders also document this condition as chronic antibiotic-dependent ileal pouchitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Postprocedural or postoperative digestive system complication.
For Medicare Advantage risk adjustment, K91.850 maps to CMS-HCC Category 463 (Artificial Openings for Feeding or Elimination) under the V28 model, adding a risk factor of about 0.673 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
K91.850 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
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.
- Chronic antibiotic-dependent ileal pouchitis
- Chronic antibiotic-refractory pouchitis
- Crohn-like disease of ileal pouch
- Ileal pouchitis
- Inflammation of ileoanal pouch
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to K91.850: its own notes plus those printed at K91 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.
- Inflammation of internal ileoanal pouch
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)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name K91.850, its category, or a range that includes it.
Excludes2 1
These codes carry an Excludes2 note naming K91.850: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Inflammation, inflamed, inflammatory (with exudation)
ileoanal (internal) pouch K91.850
intestinal pouch K91.850
Pouchitis K91.850
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Pouchitis
acute inflammation in the intestinal mucosa of the continent ileal reservoir (or pouch) in patients who have undergone ileostomy and restorative proctocolectomy (proctocolectomy, restorative).
Patient EducationClinical
After Surgery
After any operation, you'll have some side effects. There is usually some pain with surgery. There may also be swelling and soreness around the area that the surgeon cut. Your surgeon can tell you which side effects to expect.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert K91.850 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About K91.850Overview
What is the ICD-10 code for pouchitis?
The ICD-10-CM code for pouchitis is K91.850 (sometimes written as K91850). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is K91.850 (Complications of intestinal pouch) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pouchitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does K91.850 group to?
When pouchitis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 394, 395, 393, with relative weights from 0.6379 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is K91.850 a CC or MCC?
CMS lists K91.850 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 70 closely related codes in its exclusion list.
What is the ICD-9 equivalent of K91.850?
Under the General Equivalence Mappings, pouchitis converts to ICD-9-CM 569.71 (pouchitis). The mapping is a direct match.
What HCC is K91.850?
K91.850 (pouchitis) maps to CMS-HCC Category 463 (Artificial Openings for Feeding or Elimination), commonly written as HCC 463, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 188 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does K91.850 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, K91.850 adds a risk adjustment factor of about 0.673 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.526 to 0.947 depending on the payment segment). HCC 463 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 463 category page.
