ICD-10 A18.31
Billable / Specific MCCTuberculous peritonitis
About ICD-10-CM A18.31
ICD-10-CM code A18.31 represents Tuberculous peritonitis. This is a billable/specific code in the Infectious and Parasitic Diseases chapter (block A18). The 2026 edition of ICD-10-CM A18.31 became effective on October 1, 2025.
Coding Tips for A18.31
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
A18.31 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under A18.31. Per CMS ICD-10-CM Tabular 2026.
- Tuberculous ascites
Inpatient DRG Impact, MCC
codes Tuberculous peritonitis. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for A18.31
Local Coverage Determinations (LCDs) from CMS MACs that list A18.31 as a covered diagnosis.
Showing top 10 of 316 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing A18.31.
1 Cigna
5 Medicare
CPT Codes Commonly Billed with A18.31
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 82306 CMS LCD: Billing and Coding: Vitamin D; 25 hydroxy, includes fraction(s), if performed CMS LCD
- 0031U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 0173U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 0423U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 81407 CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 0349U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 81408 CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 0175U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 0032U CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
- 81220 CMS LCD: Billing and Coding: Pharmacogenomics Testing CMS LCD
Convert A18.31 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| A18.31 | 01400 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To A18.31
Other codes in section A15-A19 (Tuberculosis).
ICD-10 A18.31, Billing FAQ
Is ICD-10 code A18.31 billable? +
Yes, A18.31 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to A18.31? +
ICD-10 A18.31 includes: Tuberculous ascites.
Is A18.31 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with A18.31? +
Procedures frequently paired with A18.31 include: 82306, 0031U, 0173U, 0423U, 81407.
What ICD-9 codes does A18.31 map to? +
Per CMS GEMs, A18.31 maps to ICD-9 codes: 01400. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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