Appropriate Use of stool ova and parasite testing

September 11, 2019- A systems-based project to reduce inappropriate testing for enteric parasitic infections has been approved with the input and review of McLaren physician partners at multiple levels: Antimicrobial Stewardship Task Force, Subsidiary HVC Teams, and the HVC Steering Committee.

WHY: Given the overuse of stool O&P × 3 coupled with the inappropriateness of performing the stool tests, there is a legitimate concern about the cost-effectiveness of the test. Furthermore, many providers are unaware that the standard stool examination by microscopy for detection of ova and parasites has been replaced by more sensitive diagnostic tests.

Expert recommendations (Otto et al, 2015; Mohapatra et al, 2018):

  • Stool O&P exam should be reserved for outpatients with persistent diarrheal illness with a duration of greater than 7 days, those who are admitted to the hospital for a diarrheal illness caused by a community-acquired infection, or immunocompromised patients with suspicion of Strongyloides infection regardless of admission length.
  • Utility of the O&P examination in long term hospitalized patients (>3 days) is not recommended. Eliminating O&P examinations on hospitalized patients would decrease hospital and patient costs without altering patient care.
  • Given the very low incremental yield of second and third samples, discourage repeating the O&P test which subsequently result in increased hospital costs, laboratory work- loads, and burden on patients.
  • Giardiasis and cryptosporidiosis are the most common parasitic infections causing diarrhea in the US. When these infections are suspected, a stool immunoassay (EIA) or direct immunofluroscence assay (DFA) test is rapid, highly sensitive and superior to traditional O&P examination. E. histolytica is the third most common parasite in the US and has been reported in some US populations (e.g., men who have sex with men, children in day care, institutionalized patients), and an EIA is also available.

WHAT: Implement a systems-based project to reduce inappropriate testing for parasitic infections. Project goals are to support appropriate antimicrobial stewardship, decrease inappropriate use of stool O&P tests, standardize laboratory policies, and improve lab stewardship.

HOW: Use a multimodal approach to include three components:

  • Education (HVC web site info, posters, pocket cards)
  • Audit and feedback (HVC teams, attending physicians, ID specialists)
  • Clinical decision support algorithms and procedures
    • Stool O & P will be removed from order sets across system
    • Providers concerned about community acquired parasitic diarrhea will be directed by the lab to the cryptosporidia/ giardia antigen tests
    • Stool O & P (x1) can still be ordered through a lab request, but the patient should have a significant travel history to suggest parasitic diarrhea.

Questions or concerns about this Clinical Practice Change? Click here to contact the McLaren HVC Program.

Stool O&P Project Summary

Stool O & P testing.pdf

Choosing Wisely Lists Focusing on Stool O&P Testing

American Society of Clinical Pathology

Do not routinely test for community gastrointestinal stool pathogens in hospitalized patients who develop diarrhea after day 3 of hospitalization.

Selected References

Mohapatra, S., Singh, D. P., Alcid, D., & Pitchumoni, C. S. (2018). Beyond O&P Times Three. American Journal of Gastroenterology, 113(6), 805–818.

Otto, C. C., Shuptar, S. L., Milord, P., Essick, C. J., et al. (2015). Reducing Unnecessary and Duplicate Ordering for Ovum and Parasite Examinations and Clostridium difficile PCR in Immunocompromised Patients by Using an Alert at the Time of Request in the Order Management System. Journal of Clinical Microbiology, 53(8), 2745–2748.