✓ Evidence Based

Irritable Bowel Syndrome (IBS) Test and Diagnosis

IBS or the Irritable Bowel Syndrome is a gastrointestinal disorder that affects up to 15% of the world’s population. Statistics show that a grand number of the visits to both primary care physicians and gastroenterologists are caused by symptoms of IBS> If you are experiencing any of the common Irritable Bowel Syndrome symptoms, you should seek medical attention in order to get an accurate IBS diagnosis.

In order to receive a clear explanation, prognosis, and treatment of the syndrome, you need to visit your doctor’s office. Your doctor may decide to use the principle of ‘diagnosis of exclusion’, where they exclude other known conditions and come to the conclusion that you are suffering from IBS. Considering that there is no such thing as a specific IBS test, an Irritable Bowel Syndrome diagnosis is most often made after excluding disorders that may be the cause of the symptoms the patient is experiencing.

Irritable Bowel Syndrome (IBS) Test and Diagnosis

Irritable Bowel Syndrome Diagnosis

Irritable Bowel Syndrome Diagnosis

The diagnosis of IBS can consist of two parts: medical history and diagnostic testing.

The medical history questions a doctor may ask in order to diagnose these conditions may include questions about:

  • Symptoms, their frequency, and severity
  • Family history of similar or equal disorders
  • Medications and duration of consuming medications
  • Recent infections
  • Events that may be related to the time when the symptoms started

A doctor may decide on an IBS diagnosis without making an irritable bowel syndrome test, solely based on the medical history and current condition of the patient. If the symptoms have lasted for a minimum of 6 months, the patient is very likely to be suffering from this condition. Additionally, these symptoms most often include discomfort or pain in the abdomen, occurring at least three times every month, for a duration of 3 months.

When a doctor decides to make a diagnosis based on medical history, then the abdominal discomfort or pain is characterized in the following way:

  • There is a change in bowel movement
  • There is a change in the appearance of the stool
  • The pain improves after a bowel movement

Furthermore, a doctor may decide on a physical exam in order to place a diagnosis of IBS. During such exams, doctors listen to sounds in the abdomen of the patient with the aid of a stethoscope, check for abdominal bloating, pain or tenderness of the abdomen.

In the majority of cases, doctors decide on the diagnosis and treatment without making tests to diagnose the condition. However, they may decide to perform some tests to check for other problems or conditions and exclude them from the diagnosis. Such problems include:

  • A fever
  • Anemia
  • Family history of celiac disease
  • Family history of colon cancer
  • Rectum bleeding
  • Family history of inflammatory bowel disease
  • Unexplained weight loss

In order to help the doctor make the right diagnosis, you must give them a clear picture of your symptoms and current condition. The symptoms for this condition have changed the diagnosis criteria for ages now, starting from the year of 1978.

Two years after, the ‘Rome Criteria’ was developed. We are speaking of a classification system that we still use for gastrointestinal infections diagnosis, including the Irritable Bowel Syndrome. Such criteria is based on the symptoms and modified into the latest revision published in 2016, called Rome IV.

For a doctor to start considering IBS, they must hear of some of the most typical symptoms. Generally, the essential symptom that distinguishes this condition from others is abdominal pain. This is more complex since it may mean IBS with constipation, with diarrhea or a mix of the two. In addition, symptoms depend on the individual.


According to the latest Rome Diagnostic Criteria, a patient is suffering from IBS if they are experiencing recurrent abdominal pain that occurs at least once per week in the last three months. Additionally, this pain must be associated with at least two of the following criteria:

  • Change of stool
  • Frequency of stool
  • Defecation

This criterion is set into motion in cases where patients do not have an abnormality in the intestinal anatomy or the metabolic process that would explain the symptoms they are experiencing. Additionally, there are several things that are increasing the odds of such diagnosis, such as:

  • Abnormal blood tests such as anemia
  • Blood in the stool
  • Unexplained weight loss
  • Change in symptoms
  • Family history of GI diseases
  • New onset of symptoms in patients aged 50 or older
  • Nighttime symptoms that lead to bad quality of sleep or insomnia

Not all these symptoms are an automatic cause for alarm, but a combination of these is a step forward into diagnosis a patient with IBS. However, excluding other conditions such as hemorrhoids as a cause of rectal bleeding, is extremely important.

Some people can suffer from IBS and other chronic conditions, which must be treated separately because cause symptoms that are more serious and problems one to the other. Such problems include dyspepsia, chest pain, insomnia, anxiety, depression, urinary symptoms, gynecological symptoms, headaches, and fibromyalgia.

If all these things do not help the doctor clearly diagnose IBS, diagnostic testing comes as the next option. Such tests include:

  • Blood tests

Blood tests are used to check for blood abnormalities, such as anemia. Also, there are certain blood tests that are used to check for tissue inflammation and damage, or for celiac disease.

  • Sigmoidoscopy and Colonoscopy

Checking the rectum and the large bowel visually with a scope is another testing that may exclude IBS. This test is done when there is unexplained weight loss or rectal bleeding, or in cases where the doctor wants to screen for colon cancer if the patient is over 50.

  • Stool tests

Doctors do stool tests to exclude an intestinal parasite, bacterial infection or blood in the stool.

  • Barium Enema

The barium enema test examines the large bowel by coating it with barium and taking x-rays of it.

  • Psychological tests

Doctors may use questionnaires or tests to detect psychological problems that can be used in the diagnosis.

A good diagnosis of IBS is performed when a doctor carefully reviews the symptoms, medical history of the patient and does a physical examination that may or may not include diagnostic tests. The diagnostic procedures rarely include tests, but may do so in order to exclude other conditions that may cause the symptoms in the patients.