Inpatient Facility Coding & Compliance Alert

Heed peritonitis while coding for acute appendicitis.

As you explore ICD-10 options for appendicitis, remember to emphasize detailed documentation that lets you pinpoint the exact site of pathology and the diagnosis. “While we can all recognize the need for more detailed documentation to support proper ICD-10 coding, this documentation must come from the physicians,” says Duane C. Abbey, PhD, president of Abbey and Abbey Consultants Inc., in Ames, IA.

Background: Appendicitis can be categorized as either acute appendicitis or other/unspecified appendicitis. The documentation is the key to discerning the difference between the different types. Additional diagnosis coding options include peritonitis; an inflammation of the abdominal cavity’s lining (the peritoneum). Peritonitis can be fatal unless treated quickly with antibiotics.

Beware of Peritonitis in Acute Appendicitis

Currently, you look through the documentation to check for localized or generalized peritonitis before committing to a code. The 540 group among the ICD-9 codes relates to appendicitis, with fourth digit providing details of peritonitis:

• 540.0 -- Acute appendicitis with generalized peritonitis
• 540.1 -- Acute appendicitis with peritoneal abscess
  
• 540.9 -- Acute appendicitis without peritonitis.

The criteria for diagnosis and coding will remain the same even with the advent of ICD-10. Peritonitis will still remain the deciding factor for coding acute appendicitis. Then, you will need to look up the K35 group with a fourth expansion providing a clue toward the specificity of peritonitis. 

• 540.0 will convert to K35.2 (Acute appendicitis with generalized peritonitis) 
• 540.1 walks over to K35.3 (Acute appendicitis with localized peritonitis)
• 540.9 crosswalks to: 

                o K35.8 (Other and unspecified acute appendicitis)
                o K35.80 (Unspecified acute appendicitis)
                o K35.89 (Other acute appendicitis)

More Options: ICD-10 has brought in more accuracy through changes in descriptors depending on the involvement of the peritoneum (localized or generalized). Note that K35.3 is also used to report acute appendicitis with peritoneal abscess, as is done at present using 540.1 in ICD-9.

ICD-10 has further expanded K35.8 to two more codes, K35.80 (Unspecified acute appendicitis) that includes acute appendicitis without any peritonitis; and acute appendicitis that is not otherwise specified (NOS) and K35.89 (Other acute appendicitis).

Other Forms of Appendicitis Get More Accuracy

If the provider does not zero in a confirmed diagnosis of acute appendicitis, then the four options in ICD-9 to explore presently are:

• 541 (Appendicitis unqualified)
• 542 (Other appendicitis)
• 543.0 (Hyperplasia of appendix (lymphoid))
• 543.9 (Other and unspecified diseases of appendix).

Fortunately, there is a direct mapping of these codes in ICD-10 as well. Diagnosis 541 directly crosses over to K37 (Unspecified appendicitis) and 542 walks over to K36 (Other appendicitis).

However, the two codes in group 543 (Other diseases of appendix) have given way to six possible expansions in ICD-10. Therefore 543.0 will change to K38.0 (Hyperplasia of appendix) and 543.9 will be represented by K38.9 (Disease of appendix, unspecified). 

In addition to these, check out the following four more options available: 

• K38.1 (Appendicular concretions), 
• K38.2 (Diverticulum of appendix),
• K38.3 (Fistula of appendix) and 
• K38.8 (Other specified diseases of appendix). 

These additional options will help in narrowing the diagnosis and result in better documentation. “Thus, on the documentation side emphasis and resources should be applied to assist physicians in recognizing the types of detail that they can supply to support ICD-10 coding”, emphasizes Abbey.