Internal Medicine Coding Alert

Hint: Start your search based on the presence or absence of peritoneal involvement.

Abdominal pain can be a common symptom bringing patients to a Internal medicine physician’s office. Once common reason for acute, emergency-type abdominal pain is acute appendicitis, so ensure that you know how to code the situation when ICD-10 goes into effect.

When your physician diagnoses acute appendicitis, you will probably see the following details in the documentation:

Symptoms such as abdominal pain (R10.31, Right lower quadrant pain), that is often in the right lower quadrant although this may vary in some patients, and anorexia (R63.0, Anorexia). Some of the other symptoms could include nausea, vomiting (R11.2, Nausea and vomiting), diarrhea (R19.7, Diarrhea, unspecified) and constipation (R15.0, Incomplete defecation).

If the physician suspects a diagnosis of acute appendicitis based on the patient’s signs and symptoms, he might order many tests to confirm the diagnosis. Some of the tests that you might see in the documentation might include a CBC count, C - reactive protein, and urinalysis.

The physician might also perform x-ray of the abdominal area, ultrasound or a CT scan of the appendix following a Gastrografin enema. Ultrasound tests are performed to confirm diagnosis of appendicitis following observations found in the CT scan.

Reporting Acute Appendicitis in ICD-9

When you code for acute appendicitis with ICD-9, you need to dig into the documentation to check for localized or generalized peritonitis. Based on the presence or absence of peritonitis, you currently have three choices for reporting acute appendicitis using the ICD-9 codes:

540.0 -- Acute appendicitis with generalized peritonitis

540.1 -- Acute appendicitis with peritoneal abscess

540.9 -- Acute appendicitis without peritonitis.

Observe Peritonitis Details for ICD-10 Selection

With ICD-10, you’ll start in the same place when choosing the correct diagnosis for acute appendicitis: checking for the presence or absence of peritonitis.

Under ICD-10, code 540.0 crosswalks to K35.2 (Acute appendicitis with generalized peritonitis) with no descriptor changes. The other two codes -- 540.1 and 540.9 -- crosswalk to K35.3 (Acute appendicitis with localized peritonitis) and K35.8 (Other and unspecified appendicitis), respectively. The descriptors to the codes in ICD-10 are more specific than in ICD-9, 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.

K35.8 further expands to two different 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).

Example: An 18-year-old male patient reports to your office with complaints of severe epigastric pain that has been present for the past forty-eight hours with increasing intensity. He also complains of nausea and vomiting.

The physician conducts a comprehensive evaluation of the patient during which he observes tenderness to percussion and Dunphy’s sign (increased pain with coughing) positive. He suspects acute appendicitis and orders blood tests (CBC), a test for C-reactive protein, and urinalysis. He also asks for a CT scan. Based on the findings at examination and tests, your gastroenterologist arrives at a diagnosis of appendicitis with localized peritonitis. Once ICD-10 is in effect, you’ll report the diagnosis with K35.3.