ICD-10-CM 2027
ICD-10 code for chlamydial peritonitis
From the official ICD-10-CM alphabetic index entry “Peritonitis (adhesive) (bacterial) (fibrinous) (hemorrhagic) (idiopathic) (localized) (perforative) (primary) (with adhesions) (with effusion) › chlamydial”. Page updated September 29, 2026.
About coding chlamydial peritonitis
The ICD-10-CM code for chlamydial peritonitis is A74.81 (Chlamydial peritonitis).
Within A74.8 (other chlamydial diseases), A74.81 is specifically for chlamydial peritonitis. Related codes cover other chlamydial diseases (A74.89).
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 865 (Viral Illness with MCC, relative weight 1.3485) and DRG 866 (Viral Illness without MCC, relative weight 0.8692), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about chlamydial peritonitis ICD-10 codes
What is the ICD-10 code for chlamydial peritonitis?
- A74.81 — Chlamydial peritonitis.
Is A74.81 billable?
- Yes. A74.81 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can A74.81 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict A74.81 as a principal diagnosis.
Is A74.81 a CC or MCC?
- No. A74.81 is neither a CC nor an MCC under MS-DRG v44.0.