2027 ICD-10-CM Diagnosis Code A18.39Retroperitoneal tuberculosis
ICD-10-CM Codes›A00–B99›A15-A19›A18
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A18.39 is a billable ICD-10-CM diagnosis code for retroperitoneal tuberculosis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 371 through 373, 974 through 976. 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 18 closely related codes. Coders also document this condition as granulomatous peritonitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tuberculosis.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Granulomatous peritonitis
- Retroperitoneal infection
- Retroperitoneal lymphadenopathy
- Tuberculosis of intestine
- Tuberculosis of intestines, peritoneum and mesenteric glands
- Tuberculosis of retroperitoneal lymph nodes
- Tuberculous adenitis
- Tuberculous mesenteric adenitis
- Tuberculous peritonitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to A18.39: its own notes plus those printed at block A15-A19 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- infections due to Mycobacterium tuberculosis and Mycobacterium bovis
- diseases generally recognized as communicable or transmissible
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.
- Tuberculosis of mesenteric glands
- Tuberculosis of retroperitoneal (lymph glands)
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- congenital tuberculosis (P37.0)
- nonspecific reaction to test for tuberculosis without active tuberculosis (R76.1-)
- pneumoconiosis associated with tuberculosis, any type in A15 (J65)
- positive PPD (R76.11)
- positive tuberculin skin test without active tuberculosis (R76.11)
- sequelae of tuberculosis (B90.-)
- silicotuberculosis (J65)
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.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code, if applicable, for associated cachexia (E88.A)
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name A18.39, its category, or a range that includes it.
Applicable To 1
These notes mention A18.39.
- O98.0 Tuberculosis complicating pregnancy, childbirth and the puerperium
Excludes2 2
These codes carry an Excludes2 note naming A18.39: 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.
mesenterica A18.39
Tuberculosis, tubercular, tuberculous (calcification) (calcified) (caseous) (chromogenic acid-fast bacilli) (degeneration) (fibrocaseous) (fistula) (interstitial) (isolated circumscribed lesions) (necrosis) (parenchymatous) (ulcerative) A15.9
abdomen (lymph gland) A18.39
lymph gland or node (peripheral) A18.2
abdomen A18.39
mesenteric A18.39
retroperitoneal A18.39
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Peritoneal Disorders
Your peritoneum is the tissue that lines your abdominal wall and covers most of the organs in your abdomen. A liquid, peritoneal fluid, lubricates the surface of this tissue.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert A18.39 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A18.39Overview
What is the ICD-10 code for retroperitoneal tuberculosis?
The ICD-10-CM code for retroperitoneal tuberculosis is A18.39 (sometimes written as A1839). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is A18.39 (Tuberculosis of intestines, peritoneum and mesenteric glands) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report retroperitoneal tuberculosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does A18.39 group to?
When retroperitoneal tuberculosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 372, 974, 976, 975, 371, 373, with relative weights from 0.6945 to 3.0488 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A18.39 a CC or MCC?
CMS lists A18.39 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 18 closely related codes in its exclusion list.
Can A18.39 be reported with P37.0?
Not as a rule. The Excludes1 note at block A15-A19, which applies to A18.39, lists "congenital tuberculosis (P37.0)". 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).
