Tests and Diagnosis

The American College of Gastroenterology reports that an estimated 10 to 15 percent of American adults suffer from irritable bowel syndrome (IBS). However, only half of those will seek medical attention and receive a diagnosis (ACG, 2012). Proper diagnosis from a medical professional is important because it allows you to receive appropriate treatment and relief.

Do you experience abdominal pain and constipation? Click here to learn about IBS‐C Partner Content

IBS is a collection of symptoms that vary from one person to the next, as opposed to a defined physical condition. To help make a proper diagnosis, many specialists use the Rome diagnostic criteria. This requires you to have experienced IBS symptoms of unusual bowel habits and abdominal pain for at least three months within the previous year.

The Diagnosis Process

Your doctor will begin by compiling a complete medical history and performing a physical examination. They’ll take a full medical history to learn more about your health, such as:  

  • possible stressors in your life
  • infections
  • symptoms
  • family history of the condition
  • medications that might be worsening your symptoms 

It’s important to let your doctor know when the symptoms started and how frequently you experience them. This will help them identify patterns between behavior and discomfort.


Your doctor may order a variety of diagnostic tests if you’re experiencing severe or additional symptoms such as weight loss, anemia, and blood in the stool. Although these tests are not required for a diagnosis of IBS, they can rule out other, potentially serious conditions.

Blood Tests

A blood test can help rule out the possibility of celiac disease, a wheat allergy that produces symptoms similar to IBS, such as cramping and intestinal distress.

Stool Test

A stool sample can check for the presence of blood or parasites, which can indicate infection.

Lower GI Series

Doctors insert barium into the intestine via a tube in the anus. Then they use an X-ray to check for possible blockages. You may have some discomfort and discolored stools for a day or two after this exam.

Flexible Sigmoidoscopy or Colonoscopy

These tests allow the physician to view the rectum and colon by use of a small camera, which is inserted into the anus via a tube. As with the lower GI series, you’re usually required to undergo a liquid diet and enema before the examination. A sedative can help you relax during the procedure.

Your doctor will recommend a colonoscopy to rule out the possibility of colon cancer if you fall into a certain risk group based on age, race, or family history.

CT Scan

A CT scan of the pelvic region can help rule out other possible causes of your discomfort, such as pancreatic or gall bladder problems.

Lactose Intolerance Tests

You may experience symptoms similar to IBS, such abdominal bloating, gas, and diarrhea if you’re unable to digest dairy products. Lactose intolerance can be diagnosed through a breath test or by eliminating dairy products from your diet for several weeks.