Primary Care Coding Alert

Hint: Look for causative factor in the documentation to zero in on right ICD-10 code.

If your FP’s diagnosis is gastroenteritis, you will have to first check if the condition is infectious or noninfectious gastroenteritis. You will be relieved to know that you have one-to-one transition codes for the different types of non-infectious gastroenteritis in the ICD-10 set of codes.

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 the gastroenteritis has been identified as toxic gastroenteritis, you report 558.2. If it has been caused out of food allergy, you report 558.3. If you are reporting 558.2, you’ll have to report an additional E code to help identify the cause of the gastroenteritis. When reporting 558.3, you will have to report an additional code to identify the type of food allergy (V15.01-V15.05).

Caveat: You cannot report 558.2 or 558.3 if your FP’s diagnosis is infectious gastroenteritis. You report this with 009.0 (Infectious colitis enteritis and gastroenteritis) or 009.1 (Colitis enteritis and gastroenteritis of presumed infectious origin). You also cannot report 558.2/ 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).

ICD-10: When you begin to use ICD-10 codes in October 2015, the ICD-9 code 558.2 crosswalks to K52.1 (Toxic gastroenteritis and colitis) and 558.3 crosswalks to 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.

When the gastroenteritis has occurred as a result of food allergy or dietary regimen noncompliance, you will have to additionally report Z91.01- (Food allergy status) or Z91.02 (Food additives allergy status) to help identify the type of food allergy as the cause of the gastroenteritis.

Focus on These Basics Briefly

Documentation spotlight: 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 FP will record a detailed history that includes medications, allergies, and habits such as consumption of alcohol and travel (will be relevant to rule out infectious gastroenteritis).

Your clinician will also 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 noninfectious type of gastroenteritis.

If your FP 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 noninfectious gastroenteritis, your FP will usually find that the pain increases with palpation while this might not be present in infectious type.

Tests: Most tests that your clinician might want to undertake will be to rule out infectious type of gastroenteritis. So he will order for a stool examination (including checking the stool pH 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 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 will arrive at the diagnosis of noninfectious gastroenteritis. Based on the cause, you will have to report the diagnosis with either K52.1 or K52.2 when using ICD-10.