Irritable bowel syndrome (IBS) is a disorder of the large bowel (colon) in which the bowel overreacts to a mild stimulus – such as eating or the presence of gas by going into spasm. It is also known as spastic colon. IBS is characterised by abdominal pain, bloating and irregular bowel habits – including alternating diarrhoea and constipation.
IBS is present in 10% to 20% of adults in the US. One study conducted in a health maintenance organisation population showed the prevalence of IBS symptoms in respondents to be 19.5%.The prevalence is similar in Europe, although it may be lower in Asia and Africa. In the UK, a cross-sectional postal survey conducted in a sample of British adults (4476 people aged 20-69 years) reported a prevalence of IBS (defined as ≥6 episodes during the previous year plus Manning ≥2 criteria) equivalent to 16.7%, with a higher rate among women (22.8%) compared to men (10.5%). In Australia, a postal questionnaire (4500 people aged ≥18 years) showed prevalence for IBS according to Manning, Rome I and Rome II criteria to be 13.6%, 6.9%, and 4.4%, respectively. Equivalent types of postal surveys conducted in Asia found similarly lower IBS prevalence rates in Singapore (11.0%, 10.4%, and 8.6% according to Manning (>1 criteria), Rome I and Rome II criteria, respectively) and in China (11.5%, and 5.7% according to Manning and modified Rome II criteria), this last one showing a higher prevalence in women. Among those who seek medical help, females outnumber males at a ratio of 2:1. There are no data to suggest that there are any trends in the prevalence of the disease. A history of physical or sexual abuse has been reported in 32% to 44% of patients. IBS symptoms may also develop following enteric infections. IBS is seen in adolescents and in all adult age groups. The onset of symptoms after 50 years of age is unusual.
There are three types of irritable bowel syndrome, or IBS. They include:
IBS with constipation: This comes with stomach pain and discomfort, bloating, abnormally delayed or infrequent bowel movement, or lumpy/hard stool.
IBS with diarrhoea: This comes with stomach pain and discomfort, an urgent need to move your bowels, abnormally frequent bowel movements, or loose/watery stool.
IBS with alternating constipation and diarrhoea.
There are about an equal number of people with IBS in each category. There is also evidence that most people with IBS will alternate between types over time.
Risk factors for IBS include:
- Abnormal (too fast or slow, or too strong) movements of the colon and small intestines
- Hypersensitivity to pain caused by gas or full bowels
- A viral or bacterial infection of the stomach and intestines (gastroenteritis)
- Small intestinal bacterial overgrowth (SIBO)
- Reproductive hormones or neurotransmitters may be off-balance in people with IBS.
Anxiety or depression may accompany IBS, though these have not been found to be a direct cause of IBS.
- The exact cause of IBS is unknown. Potential causes may include sensitivity of the GI tract to gas and bloating, alteration of the fecal flora (bacteria) within the intestines, or altered levels of specific compounds or chemicals within the body, such as serotonin.
- Having a recent GI track infection and having a history of IBD may also be a risk factor for IBS. Although stress does not cause IBS, many people with IBS indicate that stress does aggravate their symptoms.
- Hormones may also play a role. For example, many women often report more symptoms when they are menstruating.
- In addition, many people with IBS report more symptoms after eating specific foods and beverages, such as spicy foods, certain fruits and vegetables, foods containing wheat, coffee, alcohol and milk.
The main symptoms of IBS are:
- Abdominal pain or discomfort that is often relieved by passing wind or faeces
- Stomach bloating
- Chronic diarrhoea or constipation, or alternating between the two
Symptoms of IBS
Other symptoms are:
- Whitish mucus in the stool/poo
- The feeling that you have not finished a bowel movement
IBS can be painful; however, it does not damage the colon or other parts of the digestive system. IBS does not lead to other health problems.
Diagnosis and test
During a physical exam, your doctor usually
- Checks for abdominal bloating
- Listens to sounds within your abdomen using a stethoscope
- Taps on your abdomen checking for tenderness or pain
In most cases, doctors don’t need to perform tests to diagnose IBS. Your doctor may perform a blood test to check for other conditions or problems. Your doctor may perform more tests based on the results of the blood test.
Doctors use blood tests to check for conditions or problems other than IBS. A health care professional sends your blood sample to a lab.
A stool test is the analysis of a sample of stool. Your doctor will give you a container for catching and holding a stool sample. You will receive instructions on where to send or take the kit for analysis, to check for blood or parasites. Your doctor may also check for blood in your stool by examining your rectum during your physical exam.
Flexible sigmoidoscopy is a procedure that uses a flexible, narrow tube with a light and tiny camera (called a sigmoidoscope) on one end to look inside your rectum and lower colon.
This procedure can show signs of conditions or problems in the lower GI tract. During the procedure, the doctor can take a biopsy. You won’t feel the biopsy.
Colonoscopy is a procedure that uses a long, flexible, narrow tube with a light and tiny camera (called a colonoscope) on one end to look inside your rectum and colon. Colonoscopy can show irritated or swollen tissue, ulcers, polyps, and cancer. A trained specialist performs this procedure.
Lower GI series
A lower GI series, also called a Barium Enema, uses x-rays to look at your large intestine. During a lower GI series, you’ll be asked to lie on a table while the doctor inserts a flexible tube into your anus. The doctor will fill your large intestine with barium. You may be asked to change positions several times during the test.
Treatment and medications
Discussions between you and your doctor can help decide the appropriate treatment plan for your specific needs. Different treatments work for different types of IBS. Avoiding individual triggers can help many people with IBS. Others choose to take medications at times when their IBS is ‘playing up’.
- Anti-diarrhoeal agents (e.g. Imodium, Lomotil, fibre supplements) can be an essential part of management in those with diarrhoea-predominant IBS
- Pain-relieving medications (e.g. opiates such as codeine) can provide effective pain relief. One of their most common side effects, constipation, may also relieve the diarrhoea of diarrhoea-predominant IBS. Pain relief may also be obtained from medications that reduce bowel spasms
- Constipation treatments (e.g. fibre supplements or laxatives) may provide relief for constipation predominant IBS
- Antispasmodic agents (e.g. mebeverine, belladonna, hyoscine and peppermint oil capsules) may ease cramping
- Tricyclic antidepressants can be effective in treating the pain of IBS, but are best prescribed for a trial period with monitoring of symptoms. Use of these medications does not mean that IBS is caused by depression
- Establishing eating routines and avoiding sudden changes of routine.
Anyone can experience digestive upset from worry or anxiety. But if you have irritable bowel syndrome, stress-related problems such as abdominal pain and diarrhoea tend to occur more often and be more severe. Finding ways to deal with stress may help prevent or ease symptoms:
Counseling. In some cases, a psychologist or psychiatrist can help you learn to reduce stress by looking at how you respond to events and then working with you to modify or change that response.
Biofeedback. This stress-reduction technique helps you reduce muscle tension and slow your heart rate with the feedback help of a machine. You’re then taught how to produce these changes yourself. The goal is to help you enter a relaxed state so that you can cope more easily with stress.
Progressive relaxation exercises. These help you relax muscles in your body, one by one. Start by tightening the muscles in your feet, then concentrate on slowly letting all of the tension go. Next, tighten and relax your calves. Continue until the muscles in your body, including those in your eyes and scalp, are relaxed.
Deep breathing. Most adults breathe from their chests. But you become calmer when you breathe from your diaphragm, the muscle that separates your chest from your abdomen. When you inhale, allow your belly to expand. When you exhale, your belly naturally contracts. Deep breathing can also help relax your abdominal muscles, which may lead to more-normal bowel activity.
Mindfulness training. This stress-reduction technique helps you focus on being in the moment and letting go of worries and distractions.
Other techniques. Set aside at least 20 minutes a day for any activity you find relaxing listening to music, reading, playing computer games or just soaking in a warm bath.