K35.33
Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
K35.33 (also written K3533) is a billable ICD-10-CM diagnosis code for acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 13 codes in category K35 (Acute appendicitis). The Alphabetic Index lists it under 18 entries. Its coding notes include 8 Excludes2 entries.
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (8 notes)
- 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)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Gastrointestinal tract and Genitourinary system clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026Hospital MCC
Counts as a major complication or comorbidity (MCC) when reported as a secondary diagnosis on an inpatient claim. It does not count when the principal diagnosis is one of the 24 codes in its exclusion list. Some MS-DRGs also ignore a CC or MCC that defines the DRG.
Source: CMS MS-DRG Definitions Manual v44, effective October 1, 2026, Appendix CInclusion terms
Conditions classified to this code.
- (Acute) appendicitis with (peritoneal) abscess NOS
- Ruptured appendix with localized peritonitis and abscess
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 18 entries
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), appendix
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), cecum
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), ileocecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), iliac (region), fossa
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), periappendicular
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), pericecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), peritoneum, peritoneal (perforated) (ruptured), with appendicitis
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), perityphlic
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), postcecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), subcecal
- Abscess (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic), vermiform appendix
- Appendicitis (pneumococcal) (retrocecal), acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative), with, peritoneal abscess
Show 6 more
- Appendicitis (pneumococcal) (retrocecal), acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative), with, peritonitis NEC
- Appendicitis (pneumococcal) (retrocecal), acute (catarrhal) (fulminating) (obstructive) (retrocecal) (suppurative), with, peritonitis NEC, localized, with, perforation, and abscess
- Appendicitis (pneumococcal) (retrocecal), with, peritoneal abscess
- Appendicitis (pneumococcal) (retrocecal), with, peritonitis NEC
- Appendicitis (pneumococcal) (retrocecal), with, peritonitis NEC, localized, with, perforation, and abscess
- Rupture, ruptured, cecum (with peritonitis), with peritoneal abscess