Diagnosis of Viral Gastroenteritis (“Stomach Flu”)

How do doctors diagnose viral gastroenteritis?

Doctors often diagnose viral gastroenteritis based on your symptoms. If your symptoms are mild and last only a short time, you typically won’t need tests.

In some cases, a medical history, a physical exam, and stool tests can help diagnose viral gastroenteritis. Your doctor may perform additional tests to check for other health problems.

Medical history

Your doctor will ask you about your symptoms, for example

  • what symptoms you have
  • how long you have had symptoms
  • how often you have had symptoms

Your doctor may also ask you about

  • recent contacts with other people who are sick
  • recent travel
  • current and past medical conditions
  • prescription and over-the-counter medicines you take

Physical exam

During a physical exam, your doctor may

  • check your blood pressure and pulse for signs of dehydration
  • examine you for signs of fever or dehydration
  • use a stethoscope to listen to sounds in your abdomen
  • tap on your abdomen to check for tenderness or pain
A doctor checking a patient’s blood pressure.
During a physical exam, your doctor may check your blood pressure and pulse for signs of dehydration.

Sometimes, doctors perform a digital rectal exam. Your doctor will have you bend over a table or lie on your side while holding your knees close to your chest. After putting on a glove, the doctor will slide a lubricated finger into your anus to check for blood in your stool. Blood in your stool may be a sign of health conditions other than viral gastroenteritis that may be causing your symptoms.

Stool tests

A health care professional will give you a container for catching and storing the stool. You will receive instructions on where to send or take the container for analysis. Stool tests can show signs of infection, inflammation, and digestive diseases and disorders.

May 2018
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.