Pathology/Lab Coding Alert

Don't lose $$ over negative results.

Stool testing for patients with diarrhea might involve screening, cultures, and/or antigen tests. Follow our experts' tips to help you sort through the lab methods and payer coverage rules to make sure you're not leaving money on the table.

1. Distinguish Stool Culture from Screening Culture

To identify enteric organisms that could be the cause of diarrhea, the lab might culture a stool specimen to encourage growth of several possible causative organisms. For instance, the physician might request a routine stool culture, which would likely include cultures for Salmonella/ Shigella and Campylobacter. Or the physician could request a comprehensive enteric pathogen culture,  which might additionally culture for Yersinia and Vibrio and possibly enterohemorragic E. coli (E. coli 0157).

Do this: Report the Salmonella/Shigella culture as 87045 (Culture, bacterial; stool, aerobic, with isolation and preliminary examination [e.g., KIA, LIA], Salmonella and Shigella species). You should additionally list 87046 (... stool, aerobic, additional pathogens, isolation and presumptive identification of isolates) for each additional pathogen culture. That would be 87046 x 4 for Campylobacter, Yersinia, Vibrio, and E. coli 0157.

Screening cultures are different: Sometimes labs will perform a culture that "screens" for a specific organism -- that means the results are either positive or negative for one specific bacterium. You should report a screening culture as 87081 (Culture, presumptive, pathogenic organisms, screening only).

2. Beware CCI Bundles

Now that you understand the distinction between a culture and a screening culture, you'll understand why CMS imposes coding restrictions for these services in the Correct Coding Initiative (CCI) edits.

CCI bundles 87081 as a column 2 code with 87046, and also bundles 87045 as a column 2 code with 87081 on the mutually exclusive edits table. CCI lists a "1" modifier indicator for both edit pairs.

What this means: You can bill a culture (87045 or 87046) with a screening culture (87081) only if the lab performs the tests on distinctly different specimens. You'll have to append modifier 59 (Distinct procedural service) to the column 2 code to override the edit, when indicated.

3. Capture Additional Identification or Antigen Test

Following a culture, the lab might perform additional studies to further identify the isolated organism(s), and you'll need to separately code for those services. If the lab tests an aerobic stool culture isolate for definitive identification using procedures such as biochemical panels, report 87077 (Culture, bacterial; aerobic isolate, additional methods required for definitive identification, each isolate) for the additional test(s).

Choose additional code for typing: If the lab performs additional tests for culture typing, you may use the appropriate code from the range 87140-87158 (Culture typing; ...) in addition to the definitive identification code, says Vickie Baselski, PhD, department of pathology, University of Tennessee Health Science Center in Memphis.

Watch for infectious agent antigen: Sometimes the lab seeks to detect an infectious organism by identifying antigen markers, such as the E. coli Shiga-like toxin. "For instance, our lab might process a direct stool specimen by inoculating enriched mac broth for growth and performing an infectious agent antigen detection by enzyme immunoassay [EIA] for Shiga toxin," says Bobbi Andera, BSMT, AMT, Business/Regulatory Manager for Sanford Laboratories in Sioux Falls, S.D.

Example: The physician orders a routine stool culture and an enterohemorragic E. coli culture along with a Shiga toxin test for a patient with bloody stool and diarrhea. The lab performs a culture for Salmonella/Shigella and inoculates sorbitol-MacConkey (SMAC) broth for E. coli 0157. The lab also performs a Shiga toxin EIA test on a direct stool specimen and reports the results as positive or negative for Shiga toxin.

Code this: Report the routine stool culture as 87045. You should additionally report the E. Coli 0157 culture as 87046. Finally, code the Shiga toxin antigen test as 87427 (Infectious agent antigen detection by enzyme immunoassay technique, qualitative or semiquantitative, multiple step method; Shiga-like toxin),

according to William Dettwyler, MTAMT, president of Codus Medicus, a laboratory coding consulting firm in Salem, Ore.

4. Don't Let Negative Culture Stop You

Coders often wonder if they can report a culture or screening culture if the lab does not isolate an organism -- in other words, if the results are negative.

Yes: You can report the appropriate base code such as 87045, 87046 (for stools) or 87081 (for single isolate detection) even if no growth occurs in the culture.

Similarly, if the lab processes an isolate using additional identification methods but determines that the isolate is a nonpathogen and does not identify the organism to the species level, you should still report 87077, according to the College of American Pathologists in CAP Today June 2001. "CPT coding represents the work the lab performs, not whether the lab reports a pathogen," Baselski says.