Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
What are the complications of irritable bowel syndrome (IBS)?
The complications of functional diseases of the gastrointestinal tract are
relatively limited. Since the symptoms are often provoked by eating, patients
who alter their diets and reduce their intake of calories may lose weight.
Fortunately, loss of weight is unusual in functional diseases, and it should
suggest the presence of a non-functional disease. Symptoms that awaken patients
from sleep also are more
likely to be due to non-functional than functional diseases.
Most commonly, functional diseases interfere with the patients' comfort and
daily activities. For example, patients who suffer from morning diarrhea
may not leave their home until the diarrhea stops. If the diarrhea is constant,
they may go only to places where they know that a toilet is readily available.
Patients who develop pain after eating may skip lunch. Very commonly, patients
associate symptoms with specific foods, such as milk, fat, vegetables, etc.
Whether or not such associations are real, these patients will restrict their
diets accordingly. Milk is the food that is most commonly eliminated, often
unnecessarily and to the detriment of adequate calcium intake. The interference
with daily activities also can lead to problems with interpersonal
relationships, especially with spouses. However, most patients with functional
disease tend to just live with their symptoms and only infrequently visit physicians
for diagnosis and treatment.
How is irritable bowel syndrome (IBS) diagnosed?
The Rome Criteria
The symptoms of IBS are varied and inconsistent among patients. Moreover,
there are no characteristically abnormal tests that can be used to diagnose IBS.
All of this has made it difficult to define IBS and identify patients,
especially for research studies. In 1992, a group of international investigators
of gastrointestinal diseases met in Rome and developed a set of criteria
to be used for diagnosing IBS. The criteria were modified in 1999 and again in
2006. These three sets of criteria are known as the Rome, I, II, and III
criteria.
The the most recent criteria, the Rome III criteria state that in order to be
diagnosed with IBS, a patient should have
abdominal
discomfort or discomfort (not described as pain) at least once weekly for at
least two months. The discomfort should be associated with two out of three of
the following features:
Relief with a bowel movement
Onset associated with a change in the frequency of bowel movement
Onset associated with a change in the form (appearance) of stool
There should be no evidence of an inflammatory, anatomic (obstructive), metabolic, or neoplastic (tumorous) cause of the symptoms.
Symptoms of dyspepsia (defined by Rome III criteria as abdominal discomfort or pain in the upper abdomen), abdominal distention, and increased flatus (passing gas, or flatulence) do not fall within this definition. Nevertheless, many patients have these symptoms along with the symptoms of IBS. It is not clear if these patients have one problem (IBS) or more than one problem.
Exclusion of non-functional gastrointestinal disease
As mentioned previously, the exclusion of non-functional disease in patients
with suspected IBS is an important concern. There are many tests designed to exclude
non-functional diseases. The primary issue, however, is to decide which tests
are reasonable to perform. Tests are selected individually since each case different. Nevertheless, there are some basic tests that
are often performed to exclude non-functional gastrointestinal disease. These
tests identify anatomic (structural) and histological (microscopic) diseases of
the intestines.
As always, a detailed history from the patient and a physical
examination frequently will suggest the cause of the symptoms.
Routine screening
blood tests are performed looking for clues to unsuspected diseases.
Examination of stool also is a part of the evaluation since it may reveal
infection, signs of inflammation, or blood and direct further diagnostic
testing. Sensitive stool testing (antigen/antibody) for
Giardia lamblia would be
reasonable because this parasitic infection is common and can be acute or
chronic.
Some physicians do blood testing for celiac disease (sprue), but the
value of doing this is unclear. Moreover, if an EGD is planned, biopsies (taking
samples of tissue) of the
duodenum usually will make the diagnosis of celiac disease.
Both X-rays and
endoscopies can identify anatomic diseases. Only endoscopies, however, can
diagnose histological diseases because biopsies can
be taken during the procedure. The X-ray tests include:
The esophagram and video-fluoroscopic swallowing
study to examine the esophagus
The upper gastrointestinal series to examine the
stomach and duodenum
The small bowel series to examine the small
intestine
The barium enema
to examine the colon and terminal ileum.
Colonoscopy to examine
the colon and terminal ileum
Endoscopy also is available to examine the small intestine, but this
type of endoscopy is complex, not widely available, and of unproven value in
suspected IBS.
For examination of the small intestine, there is also a capsule containing a
tiny camera that can be swallowed (capsule
endoscopy). As the capsule travels through the
intestines, it sends pictures of the inside of the intestines to an external
recorder for later review. However, the capsule is not widely available and its
value in IBS has not yet been proven.
X-rays are easier to perform and are less costly than endoscopies. The skills
necessary to perform X-rays, however, are becoming rarer among radiologists
because they are doing them less often. Therefore, the quality of the X-rays
often is not as high as it used to be. As noted above, endoscopies have an
advantage over X-rays because at the time of endoscopies, biopsies can be taken
to diagnose or exclude histological diseases, something that X-rays cannot do.
Exclusion of non-intestinal disease
Patients with suspected IBS often undergo abdominal ultrasonography (US),
computerized tomography (CT or CAT scans), or
magnetic resonance imaging
(MRI). These tests are used primarily to diagnose non-intestinal diseases.
(Although these tests also may diagnose intestinal diseases, their value for
this purpose is limited. As described above, X-ray and endoscopy are better
tests.) It also is important to realize that US, CT, and MRI are powerful tests
and will uncover abnormalities that are unrelated to IBS. The most common
example is the finding of
gallstones that, in fact, often cause no symptoms. This finding can cause a
problem if the gallstones are assumed to be the source of the IBS symptoms. The
problem is that surgical removal of the gallbladder with its gallstones
(cholecystectomy) is unlikely
to relieve the symptoms of IBS. (Cholecystectomy would be expected to relieve
only the characteristic symptoms that gallstones sometimes can cause.) Tests to
exclude non-intestinal diseases may be appropriate in specific situations,
although certainly not in most patients.
Evaluation of intestinal transportation
If abnormal function of the muscles of the small intestine is suspected,
tests to evaluate transportation through the small intestine or the colon (small
intestinal and colonic transit studies, respectively) are available. These
studies are done with either radioactive compounds or markers that can be seen
on X-rays of the abdomen. It also is possible to pass catheters into the stomach
and small intestine or the colon to determine if the muscles of these organs are
working normally (antro-duodenal and colonic motility studies, respectively).
Finally, constipation due to malfunction of the anal muscles can be diagnosed by
ano-rectal motility studies.
Psychiatric illness
The possibility of a psychiatric (psychosomatic) illness often arises in
patients with IBS because the symptoms frequently are subjective, and no
objective abnormalities can be identified. Psychiatric illness may complicate
IBS, but it is unclear if psychiatric illness causes IBS. If there is a
possibility of psychiatric illness, a psychiatric evaluation is appropriate.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
Gas or "intestinal gas" means different things to different people. Everyone has gas and eliminates it by belching or farting (passing it through the rectum).
Constipation is defined medically as fewer than three stools per week and severe constipation as less than one stool per week. Constipation usually is caused by the slow movement of stool through the colon. There are many causes of constipation including medications, poor bowel habits, low fiber diets, abuse of laxatives, hormonal disorders, and diseases primarily of other parts of the body that also affect the colon.
Fibromyalgia, formerly
known as fibrositis, causes chronic pain, stiffness, and
tenderness of muscles, tendons, and joints without detectable inflammation. Fibromyalgia patients have an unusually low pain threshold. Symptoms of fibromyalgia include fatigue, abnormal sleep, mental/emotional disturbances, abdominal pain, migraine and tension headaches, and irritable bladder. Treatment of fibromyalgia involves patient education, medication, exercise, and stress reduction.
In lactose intolerance, the digestive system cannot digest lactose (the main sugar in milk). Symptoms of lactose intolerance include diarrhea, flatulence, abdominal pain, abdominal bloating, abdominal distention, and nausea. There are several tests to diagnose lactose intolerance. Treatment is generally made with dietary changes, supplements, and adaptation to small amounts of milk.
Small intestinal bacterial overgrowth (SIBO) refers to a condition in which abnormally large numbers of bacteria (at least 100,000 bacteria per ml of fluid) are present in the small intestine and the types of bacteria in the small intestine resemble more the bacteria of the colon than the small intestine. There are many conditions associated with small intestinal bacterial overgrowth, to include: diabetes, scleroderma, Crohn's disease, and others. There is a striking similarity between the symptoms of irritable bowel syndrome and SIBO. It has been theorized that SIBO may be responsible for the symptoms of at least some patients with irritable bowel syndrome. Symptoms of SIBO include: excess gas, abdominal bloating, diarrhea, and abdominal pain.
Dyspepsia (indigestion) is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fluctuate infrequency and intensity. Symptoms of dyspepsia include upper abdominal pain, belching, nausea, vomiting, abdominal bloating, early satiety, and abdominal distention (swelling). These symptoms are most often provoked by eating.
Digestion is the complex process of turning food you eat into the energy you need to survive. The digestive process also involves creating waste to be eliminated, and is made of a series of muscles that coordinate the movement of food.
Irritable bowel syndrome (IBS) is a functional disease that can affect the quality of those who suffer from this condition. Individuals with IBS can make lifestyle changes that may modify or control the number and severity of episodes. Certain foods, medications, and hormone levels may trigger IBS episodes. Learn how to prevent the number and severity of IBS episodes of diarrhea and constipation.
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