Irritable bowel syndrome (IBS) affects up to 10–15% of adults. It has a significant worldwide prevalence. Although IBS is not associated with an increased risk for life-threatening illness, it is associated with a significant health care and economic burden.
Studies have shown that IBS patients have an increased number of outpatient health care visits, diagnostic tests, and surgeries. IBS can also severely compromise a person’s quality of life. IBS is second only to the common cold as a cause of absenteeism from work.
IBS is best understood as a long-term or recurrent disorder of gastrointestinal (GI) functioning. It usually involves the large intestine (colon) and small intestine with disturbances of intestinal/bowel (gut) motor function (motility) and sensation.
These gut related activities are regulated by the brain. This may also be impaired, which is why IBS is often called a brain-gut disorder.
These disturbances can produce symptoms ofabdominal pain or discomfort, bloating or a sense of gaseousness, and a change in bowel habits (diarrhea and/or constipation).
What are the symptoms of IBS?
Abdominal pain and/or discomfort is the key symptom of irritable bowel syndrome (IBS) and is associated with a change in bowel habits. This change in bowel habits may be diarrhea and/or constipation.
Individuals with IBS may either have mostly diarrhea, mostly constipation, or both diarrhea and constipation (mixed pattern). The pain is often relieved by having a bowel movement and can at times be worsened after eating.
Symptoms can change over time. There can be periods when symptoms flare up as well as periods of remission when they diminish or disappear.
In addition, the main bowel habit can vary over time. For example, some people that suffer mainly from constipation (or diarrhea) may later experience a change to constipation alternating with diarrhea.
Other common symptoms of IBS include:
- bloating (a sensation of fullness in the belly)
- urgency (the need to use a restroom in a hurry)
- mucus (white or yellow liquid) in the stool
- the sensation of incompletely passing stools
The typical features of IBS are generally recognizable by a physician.
Usually the physician will examine the abdomen of a patient with IBS and it will be normal or have tenderness. A rectal examination is also done to evaluate the functioning of the rectal floor muscles, particularly if there is incontinence or severe constipation with straining.
The most important first step is to confidently recognize the diagnosis of IBS and remove the suspicion of other diseases.
What causes IBS?
The cause of irritable bowel syndrome (IBS) is not completely understood. There are possible factors like genetics and prior adverse life experiences (e.g., infection, trauma) that can predispose someone to get IBS.
The symptoms appear to result from disturbances in colonic motility (muscle contractions) and increased sensitivity to food, gas, or stool in the bowel.
Finally, there is a tendency for the bowel to be overly reactive to various factors, which can amplify or bring about the symptoms. Examples include: eating, stress, emotional arousal, GI infections, menstrual period, or gaseous distension.
The altered patterns of colonic motility and sensation appear to be due to disruptions in the communication between the brain and gut. This interaction is known as the brain-gut axis.
These bi-directional interactions between the brain and gut are important in maintaining normal bowel function. They also respond to any potential disturbance or stressor.
In IBS, normal regulation of the brain-gut interactions become altered which leads to changes in motility and sensation within the bowel. There are a number of factors that may play a role in the alteration in the brain-gut axis.
These factors include:
- A genetic predisposition (e.g., family history of IBS) to developing IBS
- An intestinal infection prior to symptom onset
- Chronic stressful life events, or other psychosocial factors
Some of these factors may be more relevant in one individual with IBS, while other factors may be more important in another.
Does bacteria cause IBS?
There normally are trillions of bacteria in the bowel. These bacteria help break down the food we eat. They also help regulate bowel function including motility, sensation, and immune function.
The composition of these bacteria may affect aspects of health and disease.
It may be that an alteration in the number and/or the kind of bacteria in our intestines contributes to IBS symptoms in some people.
More needs to be learned about the possible role of bacteria with IBS. It is advisable to discuss this with a doctor.
How is IBS diagnosed?
The first step in making a positive diagnosis of irritable bowel syndrome (IBS) is for the doctor or other health care provider to identify if an individual has the symptoms of IBS.
This is best determined by the use of the Rome Criteria, which is a collection of the most common symptoms that typify the disorder.
This includes abdominal pain or discomfort for several months that is associated with two of the following:
- the pain or discomfort is relieved by defecation,
- the pain or discomfort is associated with an increase or decrease in stool frequency, and/or
- the pain or discomfort is associated with the stools becoming harder or softer in consistency.
The next important step is to look for signs and symptoms that are suggestive of a condition other than IBS, such as inflammatory bowel disease or celiac disease. These signs and symptoms have been referred to as “alarm signs” or “red flags.”
- anemia and other abnormal blood tests
- blood in the stool
- unexplained weight loss
- new onset of symptoms at the age of 50 or older
- family history of inflammatory bowel disease, colon cancer, or celiac disease
These alarm signs are usually not explained by IBS and can represent other medical problems. When these symptoms and signs occur, they should be brought immediately to the attention of a doctor who may perform additional tests.