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ICD-10 Guide
ICD-10 CodesK35.33

K35.33

Billable

Acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/06/2025

Code Description

ICD-10 K35.33 is a billable code used to indicate a diagnosis of acute appendicitis with perforation, localized peritonitis, and gangrene, with abscess.

Key Diagnostic Point:

K35.33 refers to acute appendicitis characterized by perforation, localized peritonitis, and gangrene, accompanied by the presence of an abscess. Clinically, patients may present with severe abdominal pain, typically starting in the periumbilical region and migrating to the right lower quadrant. Symptoms often include fever, nausea, vomiting, and changes in bowel habits. The anatomy involved primarily includes the appendix, a small pouch attached to the cecum, and surrounding peritoneal structures. Disease progression can lead to complications such as abscess formation, which may require surgical intervention. Diagnostic considerations include imaging studies like ultrasound or CT scans to confirm the diagnosis and assess the extent of perforation and abscess. Laboratory tests may reveal leukocytosis and elevated inflammatory markers. Early diagnosis and treatment are crucial to prevent further complications such as generalized peritonitis or sepsis.

Code Complexity Analysis

Complexity Rating: High

High Complexity

Complexity Factors

  • Diagnostic complexity: Requires imaging and laboratory tests for accurate diagnosis.
  • Treatment complexity: Often necessitates surgical intervention and possible post-operative care.
  • Documentation requirements: Detailed clinical notes and imaging reports are essential.
  • Coding specificity: Requires precise coding to capture the specific nature of the appendicitis and associated complications.

Audit Risk Factors

  • Common coding errors: Misclassification of the type of appendicitis or failure to document abscess presence.
  • Documentation gaps: Incomplete clinical notes regarding the severity and complications.
  • Billing challenges: Potential denials due to insufficient documentation supporting the complexity of the condition.

Specialty Focus

Medical Specialties

Primary medical specialty: General Surgery

Documentation Requirements

Standard ICD-10-CM documentation requirements apply

Common Clinical Scenarios

Various clinical presentations within this specialty area

Billing Considerations

Follow specialty-specific billing guidelines

Secondary specialty: Gastroenterology

Documentation Requirements

Standard ICD-10-CM documentation requirements apply

Common Clinical Scenarios

Various clinical presentations within this specialty area

Billing Considerations

Follow specialty-specific billing guidelines

Related ICD-10 Codes

Related CPT Codes

CPT Code

Clinical Scenario

Documentation Requirements

CPT Code

Clinical Scenario

Documentation Requirements

CPT Code

Clinical Scenario

Documentation Requirements

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

K35.33 has significant clinical implications, as it represents a severe form of appendicitis that can lead to serious complications if not treated promptly. The population health impact includes increased healthcare utilization due to emergency surgeries and potential complications. Quality measures may focus on timely diagnosis and intervention to reduce morbidity associated with perforated appendicitis. Understanding the epidemiology of appendicitis, including its prevalence and risk factors, is essential for healthcare providers to improve patient outcomes.

ICD-9 vs ICD-10

K35.33 has significant clinical implications, as it represents a severe form of appendicitis that can lead to serious complications if not treated promptly. The population health impact includes increased healthcare utilization due to emergency surgeries and potential complications. Quality measures may focus on timely diagnosis and intervention to reduce morbidity associated with perforated appendicitis. Understanding the epidemiology of appendicitis, including its prevalence and risk factors, is essential for healthcare providers to improve patient outcomes.

Reimbursement & Billing Impact

Reimbursement considerations include the complexity of the case, which may warrant higher payment rates. Common denials can arise from inadequate documentation of the complications associated with appendicitis. Best practices include ensuring that all clinical notes are comprehensive and that imaging and lab results are clearly linked to the diagnosis. Coders should also be aware of payer-specific guidelines and requirements for surgical procedures related to appendicitis.

Resources

Clinical References

  • •
    ICD-10 Official Guidelines for K00-K99
  • •
    Clinical Documentation Requirements

Coding & Billing References

  • •
    ICD-10 Official Guidelines for K00-K99
  • •
    Clinical Documentation Requirements

Frequently Asked Questions

What specific conditions are covered by K35.33?

K35.33 covers acute appendicitis with perforation, localized peritonitis, gangrene, and the presence of an abscess. It is critical to document the presence of these complications to justify the use of this code.

When should K35.33 be used instead of related codes?

K35.33 should be used when there is clear evidence of perforation, localized peritonitis, gangrene, and abscess formation. If these complications are absent, codes such as K35.31 or K35.32 may be more appropriate.

What documentation supports K35.33?

Documentation should include clinical findings, imaging results confirming perforation and abscess, laboratory results indicating infection, and detailed surgical notes if an operation is performed.