Irritable Bowel Syndrome (IBS)
Irritable bowel syndrome (IBS) is a common condition characterized by abdominal discomfort associated with altered bowel movements and is currently diagnosed according to the new Rome IV criteria.
Recent research has shown that many symptoms of IBS are related to hypersensitivity of the nerves found in the wall of the gastrointestinal tract. These nerves are distinct from those in your spinal cord and brain. For some people, IBS may arise from how the gut nerves communicate with the brain, or how the brain processes that information.
In Western countries, IBS seems to affect women twice as often as men. IBS is very common, occurring in up to 15 percent of the United States population. Most people with IBS develop their first symptoms before the age of 40, with many patients recalling the onset of symptoms during childhood or young adulthood. There appears to be a familial component, as many IBS patients report having a family member with similar symptoms. Less commonly, the symptoms of IBS develop after a severe intestinal infection; this is called post-infectious IBS.
It is important to note that IBS is very different than the similarly named disease inflammatory bowel disease (IBD).
Irritable Bowel Syndrome Types
There are four subcategories of IBS, each with equal prevalence:
- Mostly diarrhea and abdominal discomfort (IBS-D).
- Mostly constipation and abdominal discomfort (IBS-C).
- Alternating loose stools and constipation with abdominal discomfort (IBS-mixed).
- Undefined subtype (IBS-U) — symptoms vary.
Irritable Bowel Syndrome Symptoms
The main symptom of IBS is abdominal pain or discomfort associated with a change in your bowel habits. Patients with IBS may describe the abdominal discomfort in different ways, such as sharp pain, cramping, bloating, distention, fullness or even burning. The pain may be triggered by eating specific foods, following a meal, emotional stress, constipation or diarrhea.
Other symptoms include:
- Mucus in stool.
- Feeling of incomplete evacuation.
People with IBS may also experience symptoms unrelated to the intestine, including:
- Migraine headaches.
- Sleep disturbances.
- Anxiety or depression.
- Chronic pelvic pain.
Some people with IBS are able to tolerate their symptoms very well and go about their regular routine. Others find that their symptoms prevent them from experiencing a full quality of life, even including going to work or doing other important activities.
Often, stress is associated with the onset of symptoms; the symptoms then improve when the stress is gone. Other patients may experience random IBS episodes that have no obvious triggers. Still others may have long periods of symptoms, followed by long symptom-free periods.
A doctor diagnoses IBS based solely on the presence of specific symptoms and the patient’s clinical history. International research groups have helped define the symptoms for IBS diagnosis. There are currently no laboratory tests or imaging tests to diagnose IBS. A trained and experienced gastroenterologist can distinguish the classic symptoms of IBS from other symptoms that might prompt an evaluation to exclude other diseases.
Physical Exam and Blood Test
A diagnosis of IBS begins with a comprehensive physical exam during which you describe your symptoms and medical history. Your doctor may diagnose IBS based on your symptoms and history, but will also look for red flags that suggest the need to look for a different diagnosis. Red flags include:
- Onset of symptoms in someone who is more than 50 years of age.
- Unexplained weight loss.
- Anemia (low iron).
- Evidence of gastrointestinal bleeding.
- Pain or other symptoms that awaken you in the middle of the night.
If you have symptoms of IBS and a red flag symptom, you will probably need a more complete investigation. You may require further testing, depending on what your symptoms are.