ICD-10-CM 2027
ICD-10 code for peritoneum disease
From the official ICD-10-CM alphabetic index entry “Disease, diseased › peritoneum”. Page updated September 29, 2026.
About coding peritoneum disease
The ICD-10-CM code for peritoneum disease is K66.9 (Disorder of peritoneum, unspecified). The official index lists 2 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on K66.9.
Within K66, choose K66.9 (Disorder of peritoneum, unspecified) only when documentation doesn't support a more specific option: peritoneal adhesions (postprocedural) (postinfection) (K66.0), Hemoperitoneum (K66.1) and other specified disorders of peritoneum (K66.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
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) and DRG 395 (Other Digestive System Diagnoses without CC/MCC, relative weight 0.6382), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific peritoneum disease codes (official index)
Common questions about peritoneum disease ICD-10 codes
What is the ICD-10 code for peritoneum disease?
- K66.9 — Disorder of peritoneum, unspecified. More specific codes apply when the documentation supports them: N94.89, K66.8.
Is K66.9 billable?
- Yes. K66.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K66.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K66.9 as a principal diagnosis.
Is K66.9 a CC or MCC?
- No. K66.9 is neither a CC nor an MCC under MS-DRG v44.0.