Common Test-Ordering Errors
Part 7: Overordered Microbiology Tests

Ova and Parasite

October 2010

Another overordered test is the examination of stool for ova and parasites.  O & Ps are the traditional method to identify gastrointestinal parasites. The test involves microscopic examination of specially prepared fecal samples by highly trained and experienced technologists. Although appropriate for identifying many exotic parasites, the O & P procedure actually is a less sensitive method for detecting the most common fecal parasites in the United States, namely Giardia intestinalis (also known as Giardia lamblia or Giardia duodenalis) and Cryptosporidia species. These parasites may be suspected when patients present with watery diarrhea and have a supportive exposure history.  In that setting, newer ELISA tests for Giardia and Cryptosporidium are more sensitive, can be performed more quickly, and are more cost-effective initial tests.

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Ova and Parasite

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Jump to section:

• Introduction
• Testing at Mayo Medical Laboratories
• Common MML Test-Ordering Errors
• Common Microbiology Test-Ordering Problems
• Helicobacter pylori
• H pylori IgM (and IgA) Not Useful
• H pylori Diagnostic Algorithm
• H pylori Diagnostic Algorithm
• Ova and Parasite
• Parasitic Investigation of Stool Specimens Algorithm
• Initial Testing in Patients with Watery Diarrhea
• Conclusion
• Questions?