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Gastroenteritis (cont.)

Exams and Tests

Gastroenteritis is often self-limiting, and the care is supportive to control symptoms and prevent dehydration. Tests may not be needed.

If the symptoms persist for a prolonged period of time, the physician may want to consider blood and stool tests to determine the cause of the vomiting and diarrhea.

As always, taking a thorough history is of great value, as is the physical examination.

The patient will be asked if other family or friends have similar exposure or symptoms. The doctor will want to know about the duration, frequency, and description of the patient's bowel movements and whether they are vomiting. The patient will be asked how often and the amount they are urinating to help the doctor determine if fluid loss is causing dehydration. Has the patient lost any weight?

The doctor also will take a medical history, including the following:

Travel history: Travel may suggest E. coli bacterial infection or a parasite infection from something the patient ate or drank.
Exposure to poisons or other irritants: Swimming in contaminated water or drinking from suspicious fresh water such as mountain streams or wells may indicate infection from Giardia - an organism found in water that causes diarrhea.
Diet change, food preparation habits, and storage: When the disease occurs following exposure to undercooked or improperly stored or prepared food such as potato salad at a picnic, food poisoning must be considered. In general, symptoms caused by bacteria or their toxins will become apparent after the following amount of time:
- Staphylococcus aureus in 2-6 hours
- Clostridium 8-10 hours
- Salmonella in 12-72 hours
Medications: If the patient has used broad-spectrum or multiple antibiotics recently, they may have antibiotic-associated irritation of the gastrointestinal tract.

Physical examination will look for the reasons for symptoms that may not be related to infection. If there are specific tender areas in the abdomen, the doctor will want to determine if the patient has appendicitis, gallbladder disease, pancreatitis, diverticulitis, or other conditions that may be the cause of the patient's symptoms.

Other noninfectious gastrointestinal diseases like Crohn's disease or ulcerative colitis must also be considered. The doctor also will feel the abdomen for masses. A rectal examination may be considered, in which the physician inspects the anus for any abnormalities and then inserts a finger in to the rectum to feel for masses. Stool obtained during this test may be tested for the presence of blood.

The doctor may perform other lab tests, including a complete blood count, electrolytes, and kidney function tests. Stool samples may be tested for blood and different types of infection,