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March 12, 2012

Coding for Intestinal Infections
For The Record
Vol. 24 No. 5 P. 28

Intestinal infections affect the gastrointestinal tract and may be caused by viruses, bacteria, parasites, yeast, fungus, or mold. In the ICD-9-CM Alphabetic Index, instructional notes direct the coder to “Enteritis, due to, by organism” when looking up “Infections, intestinal.” However, an intestinal infection defaults to code 009.0, Infectious colitis, enteritis, and gastroenteritis. A more specific code should be assigned if the physician documentation provides greater specificity (eg, type of pathogen).

A common cause of enteritis is a virus, and the condition typically lasts for one to two days. Gastroenteritis due to a virus is classified to ICD-9-CM subcategory 008.6. Some common viruses include rotavirus (008.61); adenovirus (008.62); norovirus, also called Norwalk or Norwalk-like virus (008.63); small round virus, not otherwise specified (NOS) (008.64); calicivirus (008.65); astrovirus (008.66); and enterovirus, including Coxsackie virus and echovirus (008.67).

Viral enteritis or viral gastroenteritis without documentation of a specific virus involved is classified to code 008.8.

Another common cause of enteritis is bacteria, with symptoms typically lasting longer than two days. The code assignment for intestinal infections due to bacteria gastroenteritis depends on the organism involved. Escherichia coli (E coli) is one of the most common causes of bacterial enteritis and is classified to subcategory 008.0. A fifth digit subclassification is needed as follows:

• 008.00, E coli unspecified;

• 008.01, Enteropathogenic E coli;

• 008.02, Enterotoxigenic E coli;

• 008.03, Enteroinvasive E coli;

• 008.04, Enterohemorrhagic E coli; and

• 008.09, Other intestinal E coli infections.

Other bacterial enteritis include Aerobacter aerogenes (008.2), Proteus (mirabilis) (morganii) (008.3), Staphylococcus (008.41), Pseudomonas (008.42), Campylobacter (008.43), Yersinia enterocolitica (008.44), anaerobic enteritis NOS (008.46), gram-negative bacteria (008.47), and unspecified bacterial enteritis (008.5).

Enteritis due to Clostridium difficile (C difficile or C diff) (008.45) that grows in the large intestine typically occurs after a patient has taken antibiotics for a while. Intestinal infection due to Shigella is classified to category 004. A fourth digit subcategory is needed to identify the type of Shigella.

Intestinal infection due to food poisoning is caused by the ingestion of contaminated foods. Some of the common causes of food poisoning include Staphylococcal food poisoning (005.0); botulism food poisoning, including Clostridium botulinum (005.1); Clostridium perfringens (005.2); Salmonella gastroenteritis (003.0); bacterial food poisoning that includes Streptococcus (005.89); Trichinosis (124); Vibrio parahaemolyticus (005.4); and Vibrio vulnificus (005.81).

A common complication of an intestinal infection is dehydration (276.51). Characteristic findings of dehydration include dry mucous membranes, poor skin turgor, dry skin, sunken eyes, anorexia, weakness, dizziness, lightheadedness, deep yellow urine, and decreased urination. The laboratory values that may be present with dehydration include increased hematocrit, blood urea nitrogen:creatinine ratio (usually greater than 20:1), urinary-specific gravity (1.020 to 1.032), total protein, serum osmolality, and serum electrolytes.

When looking at these lab valves to confirm a diagnosis of dehydration, the coder must be aware of the patient’s other current diagnoses. Congestive heart failure and syndrome of inappropriate secretion of antidiuretic hormone may also affect the lab values in the same way. Treatment of dehydration includes either oral or IV fluids. Upon rehydration, the patient’s weight should increase within 24 to 48 hours because the input will be greater than the output. Also, the patient’s hemoglobin and hematocrit levels will decrease along with the total protein level. The blood urea nitrogen:creatinine ratio will also decrease during rehydration to a normal 10:1 ratio.

For coding purposes, dehydration may be sequenced as the principal or secondary diagnosis depending on the circumstances of admission and the attending physician’s judgment. Dehydration is the principal diagnosis if it is the condition established after study to be chiefly responsible for occasioning the admission. If a patient is admitted for treatment of dehydration with aggressive hydration and also has acute gastroenteritis, then the dehydration (276.51) will be sequenced as the principal diagnosis. This advice would not change even if the acute gastroenteritis was documented as infectious gastroenteritis. “The circumstances of inpatient admission always govern the selection of principal diagnosis; the condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care” (AHA Coding Clinic for ICD-9-CM, 2008, first quarter, pages 10-11).

Coding and sequencing for intestinal infections are dependent on the physician documentation in the medical record and application of the Official Coding Guidelines for inpatient care. Also, use specific AHA Coding Clinic for ICD-9-CM and American Medical Association CPT Assistant references to ensure complete and accurate coding.

— This information was prepared by Audrey Howard, RHIA, of 3M Consulting Services. The company and its representatives do not assume any responsibility for reimbursement decisions or claims denials made by providers or payers as the result of the misuse of this coding information. More information about 3M Health Information Systems is available at www.3mhis.com or by calling 800-367-2447.


Coding for Intestinal Infection in ICD-10-CM
The code structure for intestinal infection in ICD-10-CM is similar to ICD-9-CM. Intestinal infectious diseases are classified to the code block A00 to A09 in ICD-10-CM. Viral intestinal infections are classified to category A08, and the common bacterial intestinal infections are classified to category A04.

Food poisoning is also classified in this code block. Major types of foodborne illnesses include the following:

• Infection, which is the consumption of a food containing a harmful microorganism that then grows in the intestinal tract and causes an illness. Microorganisms causing infection include bacteria such as Salmonella spp, Listeria monocytogenes, Campylobacter jejuni, Vibrio parahaemolyticus, Vibrio vulnificus, and Yersinia enterocolitica; viruses such as hepatitis A, norovirus, and rotavirus; and parasites such as Trichinella spiralis, Anisakis simplex, Giardia duodenalis, Toxoplasma gondii, Cryptosporidium parvum, and Cyclospora cayetanensis.

• Intoxication is the consumption of a food containing a toxin that causes an illness. Toxins are produced by bacteria such as Clostridium botulinum, Staphylococcus aureus, Clostridium perfringens, and Bacillus cereus; chemicals such as cleaning products, sanitizers, pesticides, and metals (eg lead, copper, brass, zinc, antimony, cadmium); seafood; and plants and mushrooms. Viruses and parasites do not cause foodborne intoxication.

• Toxin-mediated infection is the consumption of a food containing harmful bacteria. The bacteria produce a toxin that causes an illness. Bacteria that may cause the toxin-mediated infection are Shigella spp and Shiga toxin-producing Escherichia coli. Viruses and parasites do not cause toxin-mediated infections.

In ICD-10-CM, category A05 includes other bacterial foodborne intoxications, not elsewhere classified. There is an Excludes 1 note, which means not coded here, that excludes the following:

Clostridium difficile foodborne intoxication and infection (A04.7)

Escherichia coli infection (A04.0-A04.4)

• Listeriosis (A32.-)

Salmonella foodborne intoxication and infection (A02.-)

• Toxic effect of noxious foodstuffs (T61-T62)

Note: Information for this sidebar was taken from the American Public Health Association via FoodSafetySite.com.

— AH