Medical history: To diagnosis IBS, a doctor must first rule out all other disease possibilities. Typically, the diagnosis begins with a medical history, including questions about the duration, severity, and characteristics of symptoms. The physician will ask about diet, stress, any medications currently being taken, and changes in bowel function. Most people with IBS have mild symptoms. Talking about bowel movements is not an easy subject for some to discuss, but it is very important to tell a doctor about symptoms.
Laboratory tests: Laboratory tests, including complete blood count, food allergy tests, thyroid function, blood sugar levels, erythrocyte sedimentation rate (ESR), liver and kidney function tests, and fecal examination, may be performed to rule out other potential causes. The thyroid, adrenal glands, and pancreas are examined for disease. Depending on symptoms, additional testing may include a lactose tolerance test and a check for the presence of blood, bacteria, and parasites in feces. Celiac disease (non-tropical sprue) is sensitivity to wheat protein that also may cause symptoms similar to those of IBS. Blood tests may help rule out that disorder.
Sigmoidoscopy or colonoscopy: An examination of the rectum and lower (sigmoid) colon is called a sigmoidoscopy. An examination of the rectum and entire colon is called a colonoscopy. The individual will have a liquid dinner the night before a colonoscopy or sigmoidoscopy. A liquid diet means fat-free bouillon or broth, gelatin, strained fruit juice, water, plain coffee, plain tea, or diet soft drinks. Whole bowel irrigation with large quantities of fluid (usually one gallon) is performed using a solution of polyethylene glycol and electrolytes (GoLYTELY®). Then, an enema (Fleet's Enema®) is used early the next morning to ensure all contents are out of the colon. An enema an hour before the test may also be necessary. During a sigmoidoscopy, a long, flexible tube with a light on the end (called a sigmoidoscope) is used to view the rectum and lower colon. The patient may be lightly sedated before the exam (usually Versed® or midazolam) and can even watch the procedure on a screen. The procedure may cause abdominal pressure and a mild sensation of wanting to have a bowel movement. Air injected into the colon can cause cramping and gas.
During a colonoscopy, a flexible tube with a light on the end (called a colonoscope) is used to view the entire colon. This tube is longer than a sigmoidoscope. The patient lies on his or her side sedated, and a tube is inserted through the anus and rectum into the colon. If an abnormality is seen, the doctor can use the colonoscope to remove a small piece of tissue for examination (biopsy). Gas and bloating are common side effects with a colonoscopy. The individual would not be able to drive home alone after sedation.
CT scan (computed tomography): A CT scan uses x-rays to take many pictures of the body that are then combined by a computer to give a detailed picture. A CT scan can often show whether the cancer has spread to the liver, lungs, or other organs. CT scans can also be used to help guide a biopsy needle into a tumor. A new way to use a CT scan is to do a "virtual colonoscopy." After stool is cleaned from the colon and the colon is filled with air, a computer can put together a picture of the inside of the colon. This method requires the same preparation as for a colonoscopy and there is some discomfort from the bowel being filled with air. If anything abnormal is seen, a follow-up colonoscopy will be needed.
Barium enema: A barium enema, also called a lower GI or gastrointestinal series, is an x-ray study in which liquid barium is inserted into the rectum and colon through the anus. Thorough cleaning of the large intestine is necessary for accurate pictures. Test preparations include a clear liquid diet, drinking a bottle of magnesium citrate (a laxative), and warm water enemas to clear out any stool particles. This test may be done in a hospital or clinic radiology department. The patient lies on the X-ray table and a preliminary X-ray is taken. The patient is then asked to lie on the side while a well lubricated enema tube is inserted into the rectum. As the enema enters the body, the patient might have the sensation that their stomach is being filled. The barium, a radiopaque (shows up on X-ray) contrast medium, is then allowed to flow into the colon. A small balloon at the tip of the enema tube may be inflated to help keep the barium inside. The flow of the barium is monitored by the health care provider on an X-ray fluoroscope screen (like a TV monitor). Air may be puffed into the colon to distend it and provide better images (often called a "double-contrast" exam). If air is used, the enema tube will be reinserted (if it had been removed; whether it is depends on who does the exam) and a small amount of air will be introduced into the colon, and more X-ray pictures are taken.
Lactose intolerance tests: Lactase is an enzyme needed to digest sugars found in dairy products. If an individual lacks this enzyme, they may have problems similar to those caused by irritable bowel syndrome, including abdominal pain, gas and diarrhea. Removing milk and dairy products from the diet for several weeks will rule out lactose intolerance. Also, a hydrogen breath test may be given. If the lactose cannot be digested, bacteria metabolize it and produce the gas hydrogen. This can be detected in the exhaled air. So a presence of hydrogen shows that lactose intolerance exists.
Rome II Criteria:
Because there are usually no physical signs to definitively diagnose irritable bowel syndrome, diagnosis is often a process of elimination. To help in this process, researchers have developed diagnostic criteria, known as Rome criteria for IBS and other functional gastrointestinal disorders (conditions in which the bowel appears normal but does not function normally). The most important symptoms to have for a diagnosis of IBS are abdominal pain and diarrhea or constipation lasting at least 12 weeks, though they do not have to occur consecutively. Other criteria include a change in the frequency or consistency of the stool, straining, urgency or a feeling that the bowels cannot be emptied completely, mucus in the stool, and bloating or abdominal distension.
The Manning Criteria: The Manning Criteria is another set of criteria established to distinguish organic causes for symptoms from those of IBS. Symptoms more likely to be found in IBS than in organic abdominal disease include pain eased after bowel movement, looser stools at onset of pain, more frequent bowel movements at onset of pain, abdominal distension, mucus per rectum, and a feeling of incomplete emptying.
signs and symptoms
IBS symptoms include abdominal pain and occasional diarrhea, often alternating with constipation, rapid transit of food with frequent bowel movements, a sense of fullness (bloating), abdominal tenderness and swelling, a lack of awareness of the bowel action (the need to "go"), and often headache and anxiety. The pain is usually felt in one of the four corners of the abdomen, especially the lower left corner.
IBS may make bowel activity much more noisy than normal. Bowel noises, such as rumblings and squeaking caused by gases being propelled through the intestines by peristalsis (contraction of muscles in the intestines that move food through it) are called borborygmi. This may be embarrassing to people with the syndrome.
The stools are often ribbon-like or pellet-like and may contain mucus. They may also be large, dry stools which are hard to pass.
Other symptoms may include burping and bad breath.
Diarrhea-predominant IBS (IBS-D): Symptoms associated with IBS-D include more than three bowel movements per day, loose watery stools, and urgency.
Symptoms associated with pain-predominant IBS include abdominal pain, cramping or aching that is relieved by a bowel movement or flatulence (gas) and cramping or aching that is relieved by a bowel movement or gas.
Bloating-predominant IBS: Symptoms associated with bloating-predominant IBS include feeling full or bloated and excessive gas.
Predominant rectal dissatisfaction: Predominant rectal dissatisfaction is a feeling of incomplete evacuation of the colon contents.
Constipation-predominant IBS (IBS-C): Symptoms associated with IBS-C include fewer than three bowel movements per week, lumpy hard stools, and straining during bowel movements.
IBS with alternating bowel habit (IBS-A): Symptoms associated with IBS-A includes alternating episodes of diarrhea and constipation.
Although the signs and symptoms for IBS may disappear for long periods of time, for most people IBS is a chronic (long lasting) condition.
Red flag symptoms that are not typical of IBS include pain that awakens/interferes with sleep, uncontrollable defecation, diarrhea that awakens/interferes with sleep, blood in the stool (visible or occult), weight loss, fever, and abnormal physical examination.
People may experience symptoms from more than one of these categories, or their classification of IBS may change over time.
risk factors and causes
Although the exact cause of irritable bowel syndrome (IBS) is unknown, contributors may include poor dietary choices, neurotransmitter imbalances, and infection.
Neurotransmitter imbalance: Up to 60% of individuals with the syndrome have psychological symptoms such as anxiety and depression. Research has reported that serotonin (a neurochemical for mood and intestinal movement) is linked with normal gastrointestinal (GI) functioning. Serotonin is a specialized type chemical called a neurotransmitter that delivers messages from one part of the body to another. Ninety-five percent of the serotonin in the body is located in the gastrointestinal tract (GIT), and the other 5% is found in the brain. Cells that line the inside of the bowel work as transporters and carry the serotonin out of the GIT. People with IBS, however, have fewer places for serotonin to bind, causing abnormal levels of serotonin to exist in the GI tract. As a result, people with IBS experience problems with bowel movement, motility, and sensation. In addition, people with IBS frequently suffer from depression and anxiety, which can worsen symptoms. Similarly, the symptoms associated with IBS may cause a person to feel depressed and anxious.
Infection: IBS may develop after a gastrointestinal infection caused by bacteria (such as Salmonella or Shigella) or parasites (such as Giardia). Infection and treatment with antibiotics can disturb the digestive flora ("good" bacteria that live in the colon) that are necessary to help break down remaining nutrients (from foods) in the colon. These disturbances in normal flora may also decrease the immune response, which helps to keep the body healthy, and as a result a patient may be more prone to illness after the antibiotic is stopped.
Age and Gender: Gender plays a clear role, as more than 80% of IBS patients in the United States are women, according to the American College of Gastroenterology. Women with IBS appear to have more symptoms during their menstrual periods, suggesting that an imbalance of reproductive hormones such as estrogen and progesterone may increase symptoms of IBS. Age also seems to be a factor. IBS usually begins during the late teens or early 20s. Metabolism (the breaking down) of female hormones occurs in the intestines and is dependent upon the "good" bacteria for proper function. Disturbances in the "good" bacteria, such as with antibiotic use, may cause the hormones to not be broken down properly, leading to hormonal imbalances.
Diet: An increased sensitivity or intolerance to certain foods may trigger or worsen symptoms of IBS. The digestive system must work hard to break down large meals, meats, or meals eaten too quickly. Fatty foods, artificial sweeteners (sucralose or Splenda® and saccharine or Sweet and Low®), chemical additives (dyes and preservatives), red meat, dairy products (milk, cheese, sour cream), chocolate, alcohol, and carbonated beverages (sodas) may trigger or aggravate episodes. Gluten contained in wheat and barley is also a common trigger for IBS. IBS may affect the absorption of nutrients, causing many individuals to have less of these nutrients available for use in the body.
Other illnesses: Sometimes another illness, such as an acute episode of infectious diarrhea (gastroenteritis) may trigger IBS.
Health complications arising from IBS include hemorrhoids (aggravated by diarrhea and/or constipation), depression, weight loss, vitamin and mineral deficiencies, and psychosocial problems such as interference with work, relationships, friends and family.