Stomach Flu Diagnosis
When making a stomach flu diagnosis, a doctor performs a physical exam and considers the patient's symptoms. Normally in the case of stomach flu, diagnosis does not include identifying the virus that is causing stomach flu (the exception is rotavirus). Before a doctor diagnoses stomach flu, he or she may rule out other conditions first, such as intussusception.
In order to make a stomach flu diagnosis (the medical term is viral gastroenteritis), the doctor will ask a number of questions about a person's medical history, including questions about:
- Current medical conditions
- Current medications
- Family history of any medical conditions
- Recent travel history
- Recent food and liquid consumption.
The doctor will also usually perform a physical exam, looking for signs and symptoms of stomach flu.
In most cases, based on the medical history and physical exam, the doctor will make a stomach flu diagnosis, but will not be able to say specifically which virus is causing the stomach flu symptoms. This is because there is no routine lab test that can detect most stomach flu viruses. The exception to this is rotavirus. A rotavirus diagnosis may be made by testing the stool for the virus using rapid antigen detection tests. Your doctor may also ask for a stool sample to rule out bacteria or parasites as the cause of your symptoms.
In special cases, such as when there is an outbreak of gastroenteritis, there is a need to identify which stomach flu virus or type of bacteria is the cause of the illness. In these cases, stomach flu viruses can often be found in stool samples of infected people by using special tests. Sometimes, blood tests looking for stomach flu antibodies are also performed when the stool tests are inconclusive or were not done. Food handlers will often be asked for a stool sample or even a blood sample to help investigate the cause of an outbreak.