The workup of diarrhea may or may not involve testing for enteric pathogens and parasites in the stool. For nosocomial diarrhea testing stool for enteric pathogens or ova and parasites rarely yields useful information. The number of unnecessary tests can further balloon since some testing algorithms recommend testing multiple times in order to detect irregular shedding.
Patient selection: diarrhea in the hospital
Nosocomial diarrhea is usually diagnosed as diarrhea starting >= 3 days after a hospital admission.
Common causes for nosocomial diarrhea may include:
(1) Clostridium difficile disease
(2) norovirus
(3) enteroviruses
(4) osmotic
(5) drug induced
(6) laxative-induced
A rule used by many hospital laboratories is to not perform stool culture or ova and parasite exams for diarrhea if the diarrhea starts > 3 days after admission.
Exceptions:
(1) immunocompromised status
(2) history of being a chronic carrier for an enteric pathogen
(3) other strong evidence of infection with an enteric pathogen (sepsis, pneumonia, etc)
(4) some unusual event such as a hospital outbreak that could explain hospital acquisition of an agent detected by this testing (food or water contamination, etc)
(5) febrile neutropenia
For Clostridium difficile testing there is also a rule to perform testing more than once a week after a positive test result.
In addition, if the hospital stay is being paid at a flat rate, then the testing may not be reimbursed. In many cases it makes more sense to defer stool testing for enteric pathogens or ova and parasites is better to defer until after discharge.
