K35.33 — Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
Is K35.33 billable?
Yes — K35.33 is billable for FY2027. K35.33 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. K35.33 may be submitted for encounters from October 1, 2026 through September 30, 2027.
K35.33 at a glance
| Code | K35.33 |
|---|---|
| Description | Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does K35.33 group to?
K35.33 sits in MDC 06 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 371Major Gastrointestinal Disorders and Peritoneal Infections with MCCmedical
- 372Major Gastrointestinal Disorders and Peritoneal Infections with CCmedical
- 373Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCCmedical
As a secondary diagnosis, K35.33 is a major complication or comorbidity (MCC), which can move a stay into a higher-paying DRG.
How is K35.33 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to K35.33. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Abscess › appendix (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › cecum (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › ileocecal (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › periappendicular (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › pericecal (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › perityphlic (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › postcecal (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › subcecal (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › vermiform appendix (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › iliac › fossa (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Abscess › peritoneum, peritoneal › with appendicitis (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Appendicitis › with › peritoneal abscess (pneumococcal) (retrocecal)
Inclusion terms
Alternative wording in documentation that is classified to K35.33.
- (Acute) appendicitis with (peritoneal) abscess NOS
- Ruptured appendix with localized peritonitis and abscess
Excludes2 — not included here — inherited from Chapter 11
The conditions below are not part of K35.33, but a patient may have both at the same time. When documentation supports it, K35.33 and the excluded code may both be reported.
- 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)
How long has K35.33 existed?
K35.33 first appears in FY2019.
- FY2023Acute appendicitis with perforation and localized peritonitis, with abscessAcute appendicitis with perforation, localized peritonitis, and gangrene, with abscess
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.