Outpatient Facility Coding Alert

Understand the cause to code it right.

If your physician diagnoses a patient with gastroenteritis, you will have to first check if the condition is infectious or non-infectious before reporting the diagnosis. The good news is that you don’t have to remember extended codes and can use one-to-one transition codes for the different types of non-infectious gastroenteritis under the ICD-10 system after the implementation date of Oct. 1, 2015.

ICD-9: When reporting a diagnosis of gastroenteritis due to drugs or food allergy, you have two ICD-9 codes to choose from:

• 558.2 (Toxic gastroenteritis and colitis)
• 558.3 (Allergic gastroenteritis and colitis).

If your physician has confirmed the disease as toxic gastroenteritis, you report 558.2. If it has been caused by food allergy, you report 558.3.

Important: If you are reporting 558.2, you have to report an additional E code to help identify the cause of the gastroenteritis. When reporting 558.3, you have to report an appropriate V code from V15.01-V15.05 to identify the exact type of food allergy.

Caveat: You cannot report 558.2 or 558.3 if your physician’s diagnosis is infectious gastroenteritis. You report that condition with 009.0 (Infectious colitis enteritis and gastroenteritis) or 009.1 (Colitis enteritis and gastroenteritis of presumed infectious origin). You also have to differentiate it from 558.2 or 558.3 when your clinician’s diagnosis is infectious diarrhea. You report this with either 009.2 (Infectious diarrhea) or 009.3 (Diarrhea of presumed infectious origin).

Follow Guideline K52.1 and Identify the Toxic Agent

When you begin to use ICD-10 codes coming October 2015, the ICD-9 code 558.2 directly crosswalks to K52.1 (Toxic gastroenteritis and colitis) and 558.3 has been matched with K52.2 (Allergic and dietetic gastroenteritis and colitis).

The guidelines for K52.1 inform you to report first from T51-T65 to help identify the toxic agent that is responsible for the toxic gastroenteritis. If the toxic gastroenteritis has been caused due to the adverse effect of any drug, you should also report from T36-T50, with a fifth or sixth character of “5,’’to identify the drug that has induced the gastroenteritis symptoms.

If your physician confirms that the gastroenteritis has occurred due to food allergy or dietary regimen noncompliance, you will have to additionally report Z91.01x (Food allergy status) or Z91.02 (Food additives allergy status) to help identify the type of food allergy as the cause of the gastroenteritis.

Document Every Single Detail

Some symptoms that you are most likely to encounter in the documentation of a patient suffering from gastroenteritis include diarrhea, vomiting, nausea, abdominal pain, fever, lethargy, cramping, and dehydration. Your physician will record a detailed history that includes medications, allergies, and habits such as consumption of alcohol and travel. Knowing these details can help the physician rule out infectious gastroenteritis.

Your clinician will query the patient about onset, duration, and severity of diarrheal symptoms and also get the patient to describe other stool characteristics that will help assess whether or not the patient is suffering from any infectious type or non-infectious type of gastroenteritis.

If your physician suspects dehydration, he will look for changes in the skin, eyes, and mucosa and will also look at the patient’s consciousness levels and check for fatigue. One factor that might point your clinician towards noninfectious gastroenteritis during examination is the type of abdominal pain. In non-infectious gastroenteritis, your GI will usually find that the pain increases with palpation while this might not be present in the infectious type.

Choose K52.1 or K52.2 Based on the Diagnosis

Most tests that your clinician might want to undertake will be to rule out any infectious types of gastroenteritis. These tests will include a stool examination (including checking the stool WBCs and to check for blood in stools) and complete blood count (CBC). In some cases, he might also want to perform blood culture or a stool culture to rule out any infection that is causing the condition.

If he suspects food allergies to be cause for the gastroenteritis, he might want to order follow up tests to detect the particular food that the patient is allergic to.

Based on history, signs and symptoms, physical examination, and results of tests, your clinician might arrive at the diagnosis of non-infectious gastroenteritis. Based on the cause, you will have to report the diagnosis with either K52.1 or K52.2 when using ICD-10.