From the Guidelines
Stool studies should be ordered for patients with diarrhea accompanied by fever, bloody or mucoid stools, severe abdominal cramping or tenderness, or signs of sepsis, as well as for immunocompromised individuals, healthcare workers, food handlers, daycare attendees, or during suspected outbreaks. These tests typically include stool culture for bacterial pathogens (Salmonella, Shigella, Campylobacter, Yersinia, C. difficile, and STEC) 1. The indications for stool studies also include patients with persistent abdominal pain, especially school-aged children with right lower quadrant pain mimicking appendicitis, and people with fever at epidemiologic risk for yersiniosis 1. Additionally, stool specimens should be tested for Vibrio species in people with large volume rice water stools or exposure to salty or brackish waters, consumption of raw or undercooked shellfish, or travel to cholera-endemic regions within 3 days prior to onset of diarrhea 1.
- The following patient populations should be considered for stool testing:
- Immunocompromised individuals, especially those with moderate and severe primary or secondary immune deficiencies 1
- People with acquired immune deficiency syndrome (AIDS) with persistent diarrhea, who should undergo additional testing for other organisms including Cryptosporidium, Cyclospora, Cystoisospora, microsporidia, Mycobacterium avium complex, and cytomegalovirus 1
- Travelers returning from endemic areas with diarrhea, who should undergo specific parasite testing 1
- The timing of specimen collection is important, with ideally three separate stool samples collected on different days for parasitic examinations, while fresh specimens are crucial for bacterial cultures 1.
- Patients should be instructed to avoid contaminating specimens with urine or toilet water and to refrigerate samples if immediate transport to the laboratory isn't possible 1.
- These tests help distinguish infectious from non-infectious causes of gastrointestinal symptoms, guiding appropriate treatment decisions and preventing unnecessary antibiotic use 1.
From the Research
Indications for Ordering Stool Studies
The following are indications for ordering stool studies:
- Severe dehydration 2, 3
- Bloody stools 2, 3, 4
- Persistent fever 2, 3
- Immunocompromised patients 2, 3
- Suspected nosocomial infection or outbreak 2
- Red flag symptoms such as weight loss, clinical and laboratory signs of anemia, and palpable mass in the abdomen 3
- Chronic diarrhea with unknown cause 4
- Inflammatory bowel diseases with diarrhea 5
- Malabsorption syndromes 6, 4
- Gastrointestinal infections 6
Stool Tests
Stool tests can include: