Making an accurate and timely diagnosis of irritable bowel syndrome is critical for the proper treatment of this condition. First, an accurate diagnosis identifies and provides a name for the multiple symptoms that have been troubling the patient, sometimes for years. Second, the patient learns that there are many other people who have similar symptoms; people who have IBS often suffer in silence, not realizing that others share similar problems. Third, a definitive diagnosis provides the opportunity for the patient to become informed about this medical condition. He or she can then research the topic and talk to family members, friends, and coworkers, probably discovering that some of them also have IBS symptoms. Knowledge truly is power for anyone with a chronic medical condition, and being informed significantly improves communication between patients and their health care providers and enhances the effectiveness of treatments. Fourth, making a definitive diagnosis of IBS often ends the need for further testing (see Chapter 8) and the parade of normal results, which can be confusing (“Why are all of these tests normal if I feel so crummy?”), time consuming, expensive, and at times, even risky. Finally, and most important, once a clear diagnosis of IBS is made, appropriate treatment can be initiated.
The accurate diagnosis of any medical condition is based on three key components: a thorough review of the patient’s history, a careful physical examination, and, when necessary, appropriate diagnostic tests or studies. This principle of performing all three components is followed whenever a health care provider begins evaluating a patient for any type of medical problem. However, the amount of time spent on each component will vary greatly, depending on the type and complexity of the problem. For example, with a patient who has a simple urinary tract infection (UTI), the doctor will want to know what the symptoms are, when they started, and if the symptoms are similar to UTIs the patient had in the past. An abbreviated physical examination is usually performed, and a urine sample is sent to a laboratory for analysis (typically a urinalysis and urine culture). For a more complicated problem, such as infertility due to endometriosis, an extensive list of questions will need to be answered, a comprehensive medical examination will need to be performed, and extensive testing, possibly including exploratory surgery, will be required.
In some cases, the diagnosis of a particular problem can be made in a single office visit using only a brief focused history and physical examination, without performing any tests. Examples include a classic migraine headache, low back pain from overuse, or a sinus infection that develops after a cold. In other cases, the diagnosis of a problem may require multiple visits, with repeated and more focused examinations, and extensive and specialized testing. The latter is often the case with diseases that have vague, intermittent, or fluctuating symptoms (such as multiple sclerosis) or diseases that progress very slowly over time (like Alzheimer’s disease).
For many patients, unfortunately, the diagnosis of IBS can be an unnecessarily lengthy, difficult, and expensive experience. In part, this is because people who have IBS are often given an inaccurate diagnosis at first. It is not uncommon for patients who have IBS to be told that their symptoms represent acid reflux disease, inflammatory bowel disease (such as Crohn’s disease or ulcerative colitis), or a food allergy. This mis-diagnosis occurs because many of the symptoms of IBS (abdominal discomfort, bloating, and diarrhea) are quite “nonspecific,” that is, they are found in many different disorders rather than being specific to IBS. This is the case with many medical problems, which is why combining a careful history with a thorough physical examination and the use of appropriate tests is so important. Also, in the past, many patients who had IBS were told that their symptoms were “all in your head.” Fortunately, this statement is rarely made by doctors now. The mistaken belief that many or all IBS symptoms were imagined by a patient developed because the tests available at the time were unable to identify an organic process that could account for the patient’s symptoms, the way pneumonia can be diagnosed by a chest x-ray. This misimpression was reinforced by the fact that it is common for people who have chronic illnesses to become depressed or anxious. The unfortunate combination of diagnostic test results that were normal and symptoms of psychological distress led many frustrated doctors to believe that IBS symptoms were the result of a “nervous” disorder, like the anxiety or depression that the patient was experiencing.
In addition to the problem of misdiagnosis, many people who have IBS receive a delayed diagnosis. Although many people who have IBS first note symptoms in their late teenage years or early twenties, for patients with moderate symptoms the average time between the onset of symptoms and the diagnosis of IBS is at least three years. This delay in diagnosis and treatment occurs for a number of reasons. Many patients are uncomfortable discussing bloating, diarrhea, and abdominal pain, even with their doctors. They feel awkward describing these somewhat personal and intimate bodily functions to strangers, and they are not familiar with the vocabulary commonly used to effectively discuss their symptoms. Some people hesitate to voice their fears and concerns to their doctors, not wanting to be thought of as “complainers” by their doctor, so they minimize their illness. People who do not discuss their symptoms, even with family or friends, may believe they are the only one with these worrisome symptoms and assume that there is nothing a doctor could do for them. These feelings can lead to a sense of isolation and further reluctance to discuss symptoms. Many people avoid consulting a professional about symptoms of illness because they are concerned that their symptoms represent a severe problem, such as cancer, and they don’t want to receive bad news. Finally, in the case of chronic illnesses, many patients become accustomed to their symptoms, no matter how disabling, managing them in their own way or surrendering to them, and only seek care when their typical symptoms change for the worse or become overwhelming.
The diagnosis of IBS should not be a lengthy and difficult process. With a detailed history, a careful physical examination, and appropriate tests, IBS can be accurately diagnosed at the first office visit in the vast majority of patients.
At your initial office visit with any health practitioner—internist, family practitioner, physician’s assistant, nurse practitioner, gynecologist, or gastroenterologist—the first part of the appointment will be spent reviewing your medical, surgical, medication, and family history. The doctor will also ask about your habits (exercise, diet, tobacco use, alcohol use, drug use), your social situation (single, married, widowed, separated, partnered, children), your work history (employed, working at home or volunteering, retired, disabled), and whether you have any allergies to medications or foods. However, the focus will be on your current problem. Many physicians greet their patients with an open-ended question such as “What brings you in today?” or “How can I help you today?” This is your chance to let the doctor know, in your own words, what symptoms you are currently experiencing and why you called for an appointment. It is also a good time to let the doctor know of any previous physician visits for the same problem, to express your thoughts and concerns, and to bring up any specific questions you want answered.
The first few minutes of a doctor’s visit are important, because they set the tone for the rest of the visit and for future visits as well. Here are two examples of first office visits to the same specialist; they differ dramatically in their tone, content, and outcome.
David, a 23-year-old law student, was referred to Dr. Hannah Rose, a gastroenterologist, for the evaluation of abdominal pain, bloating, and diarrhea. David had already been shown to a chair in the examination room by the nurse when Dr. Rose entered. She introduced herself: “Good morning. I’m Dr. Rose. What brings you in today?” and David replied that he had a one-year history of lower abdominal pain that appeared to be associated with diarrhea. He said that he also felt very bloated at times, despite watching his diet and working out at the gym, where he did a lot of sit-ups. He admitted that he was a little embarrassed to see a doctor about these problems because he thought he was quite healthy, but his father had died of colon cancer in his early sixties, and David wanted to make sure that he was okay.
For the next five minutes, David carefully related his symptoms, reviewed how he had tried to treat these symptoms with diet and exercise, and mentioned how the symptoms affected his everyday life. Dr. Rose listened carefully without interrupting and then asked David if there was anything else he wanted to discuss before she started asking him some specific questions about his problem. David confessed that he had brought a list of questions that he wanted answered but said he would be happy to hold them until the end of the visit, as he was sure most would be addressed during the rest of the interview.
Colin was a 27-year-old computer engineer. He was referred to Dr. Rose by his internist for evaluation of chronic abdominal pain, bloating, and diarrhea. He was seated in the examination room when Dr. Rose entered and said: “Good afternoon, I’m Dr. Rose. What brings you in today?” Colin replied, “Didn’t my doctor tell you?” “Well, yes,” said Dr. Rose, “I do have some notes from your doctor, but I always like to hear the story firsthand from the patient. Can you tell me about this pain you’ve been having?” Colin answered, “Well, it hurts a lot.” A period of awkward silence ensued while Dr. Rose waited for Colin to elaborate on this initial comment. When no further details were forthcoming, Dr. Rose asked Colin if he could tell her when the pain began. Colin replied, “A long time ago.” Again, a period of silence followed. Realizing that using open-ended questions was not likely to elicit the information she needed, Dr. Rose continued the interview with a long list of questions that could be answered with a simple “yes” or “no.”
These two cases, both involving young men with similar symptoms seeing the same doctor, reveal how important, and how much in control, the patient can be during the first part of the interview. David was open, told his story in his own words, voiced his concerns, and let the doctor know that he had some questions he wished to have answered. This turned out to be a productive visit, and David left feeling confident that Dr. Rose would be able to assist him with his problem. Colin, on the other hand, was not able to tell his story in his own words. He did have some questions and concerns, but he was never able to voice them, because Dr. Rose had to spend nearly the entire visit drawing out of him information that Colin likely could have provided in just a few minutes if he had given it some thought beforehand. Colin left the office later that afternoon feeling unsatisfied and somewhat frustrated. Dr. Rose finished the interview feeling unsatisfied and drained.
The point of describing these two interviews is to highlight three important facts about doctor-patient interviews. First, patients are in control of the interview to a large degree, within constraints like the scheduled length of the visit. Second, by being open, being prepared, voicing your concerns, and bringing a list of questions, you can ensure that the interview will be informative and productive for both you and the physician. To help you prepare, some tips are listed in Table 7.1 (see also Chapter 23). Third, some doctors do not have a good bedside manner, and you can find this out during the initial interview. If your doctor is not able to answer your questions or treats you in a rude or brusque manner, find another doctor. Ask friends and family members for names of doctors they have had good experiences with. Remember that your doctor does not need to be your best friend; however, you need to have confidence that your doctor will do her or his best on your behalf.
During history taking at an office visit to evaluate symptoms of IBS, the two key symptoms to bring to the doctor’s attention are abdominal pain and altered bowel habits. Which of these two components is emphasized by the patient usually depends on which the patient finds most disturbing. Let’s look in detail at the IBS symptoms that a patient and doctor should discuss.
The presence of abdominal pain is required for the diagnosis of IBS. Clinicians often use specific guidelines (called the Rome II criteria) to help make the diagnosis of IBS (see Table 7.2). These guidelines state that people diagnosed with IBS should experience symptoms of IBS at least six months before diagnosis and that these symptoms should be active (present) during the preceding three months. Patients frequently ask me how many days they should be experiencing abdominal pain or discomfort to be correctly diagnosed as having IBS. Somewhat surprisingly, abdominal pain does not have to be present every day to meet criteria for having IBS. Abdominal pain or discomfort should be present at least three days of the month, for the last three months. People who have IBS may have lower abdominal pain one or two days of the week, and then have one week with minimal or no discomfort, followed by a week with three to four days of severe pain or discomfort. It is common for people who have IBS to have periods of “good” days or weeks followed by periods of “bad” days or weeks. Of course, every person is different, and some people who have IBS do experience daily abdominal pain or discomfort in addition to their symptoms of constipation or diarrhea.
Table 7.1. Tips to Maximize Your First Visit to Your Doctor
• Bring a list of the prescription and over-the-counter medications you take and any vitamins and herbal supplements you may use. Note the dosages and the time of day when you take them. • If you have taken other medications in the past for the same symptoms, bring a list of those as well. Note the dosages and how long you took the medications, if you remember. • If you have seen other doctors for the same problem, bring a list of their names and specialties. • If you have had any tests for this problem in the past, have your other doctor(s) send them to this doctor in advance of your arrival. These might include the results of blood work, x-ray studies, endoscopy reports, or more specialized testing. If the tests were done recently, you may be able to avoid having to repeat them. • Think about your symptoms before you come in for your appointment. Make a list of your symptoms. Try to answer the following questions: When did the symptom start? How would you describe the symptom? What makes your symptoms better? What makes them worse? • Bring a list of your concerns or fears. You may think they would never leave your mind, but for many reasons they might not get discussed without such a reminder. • Bring a list of questions that you want answered. Put these questions in the order of importance to you. Because of time limitations, the doctor may be able to get to only some of the questions on the first visit, although other questions on the list can be addressed at follow-up appointments. |
Table 7.2. The Rome III Criteria Defining Irritable Bowel Syndrome
• Recurrent abdominal pain or discomfort • Onset of symptoms at least six months earlier • Symptoms must be present at least three days per month within the last three months • Symptoms of abdominal pain or discomfort must be associated with at least two of the following:
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To be accurately diagnosed with IBS, patients should note an association with abdominal pain or discomfort and altered bowel habits. People who have IBS experience abdominal pain or discomfort with at least two of the three following symptoms: changes in stool frequency, changes in stool consistency, and improvement in pain or discomfort after having had a bowel movement. In less scientific terms, abdominal pain should be related in some way to having a bowel movement. For many patients who have IBS, the abdominal pain happens just before having a bowel movement. The pain may occur as a crampy sensation or discomfort in the left lower quadrant of the abdomen, along with the urge to empty the bowels. Often this pain goes away after evacuation. Sometimes the pain develops during, or is made worse by, having a bowel movement. The exact reason why this pain develops is unknown, and it may represent any of a variety of processes, including spasm in the colon, persistent contractions in the colon, stretching of the colon, or increased awareness of normal peristalsis (the concept of increased vigilance or hypersensitivity in the gut).
For other patients who have IBS, however, the pain occurs unpredictably, without any rhyme or reason, at any time of the day. This unpredictability is frustrating to patients and can be quite worrisome and socially inhibiting. Finally, although some patients who have IBS have disordered sleep, many patients who have IBS note that pain occurs immediately on awakening in the morning but is absent at night. Physiologically, this makes sense, since the GI tract is quietest at night, because most food is eaten during the day and first half of the evening.
Although the chronic abdominal pain of IBS can be discouraging, frustrating, exhausting, and even depressing to some patients, it is not dangerous. However, the presence of abdominal pain can, in some situations, mean that something dangerous is developing in the abdominal cavity (or elsewhere, in unusual circumstances). For example, in a teenager, the development of new abdominal pain in the lower right portion of the abdomen along with fever and an elevated white blood cell count often indicates the presence of appendicitis. Abdominal pain in the right upper quadrant of the abdomen with nausea, vomiting, and abnormal liver tests may indicate hepatitis (inflammation in the liver) or gall bladder disease. The careful history and physical examination performed by the health care provider helps differentiate the abdominal pain of IBS from that caused by a variety of other medical conditions.
The second most common complaint voiced by patients who have IBS is that of abnormal bowel habits. Large-population studies conducted over the years have shown that the majority of healthy people report having anywhere from three bowel movements per week to three bowel movements per day. For most people who do not have IBS, their individual pattern of bowel habits is fairly consistent for a given individual over time. In people who have IBS, one of the first symptoms they notice is a change in their usual bowel pattern. This is worrisome to many patients, because they’ve heard that a change in their bowel habits could indicate colon cancer. In addition, nearly a quarter of patients who have IBS have fluctuating bowel habits during the course of the year. Keeping track of bowel habits is important, because if the patient alternates between symptoms of constipation and diarrhea, it is difficult to decide which type of treatment will be best. (Part 3 of this book discusses treatments.)
People who have IBS usually have one of three patterns of defecation: constipation predominant, diarrhea predominant, or alternating constipation and diarrhea, sometimes called a mixed pattern. Patients who have IBS and constipation often report the passage of rock-hard, pellet-like stool called scybala. In addition, they may describe excessive straining in an attempt to move their bowels, prolonged time spent in the bathroom (hours in some cases), feelings of incomplete evacuation, and pain or discomfort with defecation.
IBS patients prone to diarrhea often find that the first bowel movement in the morning is of normal consistency but subsequent bowel movements become increasingly loose and are accompanied by significant urgency and gassiness. Urgency is best defined as the feeling of having to race to the bathroom out of fear of having an accident. The urgency and cramps may be temporarily relieved by the passage of stool; however, these feelings may quickly return and precipitate yet another bowel movement. Mucus may cover the stools or be passed alone. As described previously, patients who have IBS often have fecal urgency and lower abdominal discomfort during the period following a meal (the postprandial period). This reflects an exaggerated or heightened gastrocolic reflex (see Chapter 6).
Bloating and abdominal distention are also common symptoms experienced by people who have IBS. Bloating is a sense of gassiness or fullness throughout the abdomen. Distention is enlargement or stretching of the abdomen. Patients often say that their abdomen feels “tight” and that on days when they are very bloated they can’t wear certain form-fitting clothes because their belly is so distended. These symptoms may reflect the presence of increased amounts of abdominal gas or an increased sensitivity to normal amounts of intestinal gas. Increased gas production can occur in patients who have lactose or fructose intolerance, in people who ingest large amounts of fiber (whether dietary fiber or a fiber supplement), and in those who ingest legumes (beans, for example) that contain stachyose and raffinose (see Chapters 10 and 19). Some patients who have IBS also suffer from aerophagia, an uncommon condition in which air is inadvertently swallowed rather than inhaled.
Although bloating and distention are frequent and troubling symptoms, they rarely reflect a dangerous problem. Contrary to popular belief, most people who have IBS do not produce more intestinal gas than people who do not have IBS. People with IBS do, however, have a decreased tolerance of distention from normal amounts of intestinal gas. Some studies have shown that patients who have IBS have difficulty evacuating intestinal gas, so the gas remains in the GI tract longer, leading to feelings of fullness, bloatedness, and tightness across the abdomen.
During the history-taking part of your office visit, your doctor may ask you a series of questions that do not immediately seem relevant to your problem. These questions are designed to see if you have a dangerous organic problem, such as a bleeding ulcer, liver disease, or cancer, rather than the troublesome but nondangerous condition of IBS. The doctor may ask you about your weight. When people lose weight without trying to, it may reflect a serious medical problem, especially in older patients. Weight loss is not associated with IBS, and thus unintentional weight loss cannot be blamed on IBS and always warrants further investigation by your doctor. Your doctor will also ask about symptoms that would indicate anemia (a low red blood cell count), about evidence of blood in your stool, and about prior episodes of bleeding from your gastrointestinal tract. Anemia and bleeding are also not directly associated with IBS, and thus any evidence of bleeding or anemia will trigger an investigation to determine the underlying cause. If you have diarrhea, your doctor will take a careful travel history to look for evidence of a recent viral, bacterial, or parasitic infection, including giardia and entamoeba histolytica (amebiasis). In addition, your doctor will ask about your diet, recent antibiotic use, and medications, because all of these can cause diarrhea.
As the interview progresses, your doctor may ask you about the presence of what are called “constitutional symptoms.” These symptoms include: fatigue, myalgias (muscle aches), arthralgias (joint aches), fevers, chills, and night sweats. Although occasionally present in patients who have IBS, these symptoms can occur for a variety of reasons. There is no evidence that IBS directly causes these symptoms; typically they result from other medical problems, such as a viral infection, fibromyalgia, arthritis, hypothyroidism, or, rarely, cancer.
The doctor will ask you about your family history and pay particular attention to whether any first (mother, father, sister, brother) or second degree (grandparent, aunt, uncle, cousin) relatives in your family had inflammatory bowel disease, celiac disease, or any type of gastrointestinal cancer (colon cancer, stomach cancer, esophageal cancer). Patients with symptoms of IBS who have a first degree relative with any of these diseases may need to have specialized laboratory or diagnostic tests.
As the interview progresses your doctor will likely ask a series of questions related to other parts of the gastrointestinal tract, such as, Do you have burning in your chest that moves up into the mouth or throat? (acid reflux); Have you ever had pancreatitis? Have you ever been jaundiced? (liver problems). In addition, he or she will do what is commonly referred to as a “review of systems.” These questions are a way to quickly review a patient’s general medical condition and locate any other medical problems that may need to be addressed. This list includes questions related to the heart, lungs, kidneys, musculoskeletal system, vascular system (arteries and veins), central nervous system, endocrine system (glands like the thyroid and pituitary), and genitourinary system.
Your doctor may also ask whether you have ever suffered any type of abuse. The term abuse is not limited to just physical abuse but also includes any form of mental, emotional, or sexual abuse. Although this question surprises many patients, many research studies have shown that patients who have functional bowel disorders like IBS are more likely to have a history of abuse than patients who have other medical conditions. Some doctors will raise this issue at the time of the first office visit, while others may wait until a doctor-patient relationship has been established, after several visits. If you have experienced abuse, you can improve your doctor’s ability to care for you by bringing this to his or her attention. The timing of this discussion depends on both the patient and the physician. When you decide to bring this issue to your doctor’s attention, it should be done when there is enough time for the issue to be dealt with carefully, not at the end of the visit as you are walking out the door.
The next part of the office visit is the physical examination. The physical generally starts with some simple measurements, such as height, weight, blood pressure, heart rate, and respiratory rate. The extent of the physical examination will depend on whether you are seeing your primary care doctor (internist, nurse practitioner, physician assistant, obstetrician, gynecologist, or family practitioner) or a specialist (for suspected IBS, a gastroenterologist). In addition, the extent and complexity of the examination will depend on the nature of your symptoms and whether this is your first visit or a follow-up visit.
The physical exam is important for many reasons. It is a critical part of the search for the cause of your symptoms; it can determine that another condition, not IBS, is causing your problems. For example, patients who have celiac disease may also have diarrhea and bloating, but a careful physical examination may reveal evidence of anemia and characteristic skin lesions, often seen in people who have a wheat allergy but not in people who have IBS. Patients who have inflammatory bowel disease (IBD) will exhibit symptoms of abdominal pain and diarrhea, just like those who have IBS, but will often reveal characteristic changes in the mouth, skin, eyes, or skeletal system that people who have IBS do not have. Also, people can have more than one disease at the same time. Although a single unifying diagnosis would be easier for both doctor and patient, it is not uncommon for patients to have several ongoing processes at once. Thus, a physical examination for symptoms of IBS may uncover a malignant skin lesion or an enlarged lymph node that otherwise would have gone unrecognized. Even if a patient has been diagnosed with IBS in the past, a repeat examination is important to verify the response to treatment and to see whether or not new problems have developed.
The physical examination of patients being evaluated for IBS is safe, and many people find a careful exam by an experienced doctor reassuring. Your doctor will probably examine your head and neck first, inspect your mouth, and then focus on your heart, lungs, skin, extremities (arms and legs), and nervous system. The nervous system is assessed by checking your reflexes and determining whether you can feel different sensations, such as pressure, in your extremities. Most doctors, especially gastroenterologists, will center their examination on the abdomen. This is appropriate, because all of the symptoms of IBS are related to the abdomen. The initial part of the examination begins with the doctor simply looking at your abdomen. This is done to check for scars, to check for asymmetry (generally the abdomen is fairly symmetrical, meaning that the left and the right side look alike; if it is asymmetrical it could indicate some underlying problem), and to look for evidence of obvious structural problems such as a mass or tumor. Then, putting a stethoscope to your abdomen, the doctor will listen for the normal sounds associated with peristalsis in the intestinal tract. These sounds will reveal if there is an obstruction of the intestinal tract. The doctor will also be able to hear the blood pulsating through some of the arteries in your abdominal cavity; if partially blocked, these arteries sound very different from arteries that are wide open.
The doctor will then “palpate” the abdomen, gently pressing with her or his hands. Palpation may reveal some tenderness or firmness, especially in the left lower quadrant over the sigmoid colon. (The anatomy of the GI tract is discussed in Chapter 6.) Stool is often present in the sigmoid colon, in patients who have and do not have IBS, and this can usually be felt. Patients who have IBS often have spasms in the sigmoid colon, which may account for tenderness. If the examination is very painful, or if the doctor finds evidence of an enlarged liver or spleen or evidence of fluid in the abdominal cavity (ascites), then further investigation will be called for, since these findings are not compatible with the diagnosis of IBS and will need to be explained. The doctor may tap on (“percuss”) your abdomen, listening for different sounds. This gives information about the size of organs and whether the area under the skin is hollow, solid, or fluid filled.
Although not the most popular part of the examination for patients, a rectal exam should be performed at the initial office visit (unless recently performed by another doctor and completely normal). This part of the exam is important because it can detect a variety of medical problems that have symptoms that mimic those of IBS. Most doctors perform this part of the examination with the patient lying on his or her left side (on the left hip and shoulder) with both knees partially drawn up toward the chest. This allows the doctor to get a clear look at the area around the anus (the muscular area at the end of the rectum [see Chapter 6]). Some doctors prefer to perform this examination with the patient on the right side or standing up. During the rectal examination, hemorrhoids (dilated blood vessels) may be seen; these are especially likely in patients who strain significantly during bowel movements. Fissures, or small tears, may be seen, which might indicate the passage of hard stool or an alternative diagnosis, such as Crohn’s disease, a form of inflammatory bowel disease. The presence of an anal fissure may explain a history of rectal bleeding, especially in patients who have constipation and straining. The doctor may test sensation in the anal area and check to see if reflexes are normal in this area. With a lubricated, gloved finger, the doctor will check the anal canal and the rectum for signs of bleeding, internal hemorrhoids, a blockage from impacted stool, a stricture (narrowing), or a mass. Patients who have IBS often have some tenderness in the rectum, due to visceral hypersensitivity and muscular spasms. Significant tenderness, evidence of a mass, or the presence of blood in the rectum warrants further investigation.
The third component of the initial office visit involves diagnostic tests. Most people who have IBS do not need extensive laboratory, radiological, or invasive testing. In the past, patients were often subjected to multiple diagnostic studies in an attempt to find out why they were suffering from abdominal pain, bloating, and constipation. It was not unusual for a patient who has IBS to have undergone a whole series of tests, only to be told that everything was normal and that nothing was wrong. These studies often included blood tests, x-rays of the abdomen and chest, an ultrasound of the gall bladder, an x-ray of the small intestine, a CT scan of the abdomen and pelvis, a barium enema or colonoscopy, and an upper GI series or upper endoscopy. That these tests usually all had normal results confirms what we now know, that IBS is a functional disorder of the gut and is not caused by an organic lesion or structural problem in the GI tract.
Our greater understanding of IBS has led to a dramatic change in the way doctors evaluate patients for this condition. We now realize that extensive testing rarely turns up a cause of patients’ chronic symptoms of abdominal pain, bloating, constipation, or diarrhea. Several studies have shown that extensive testing of all patients who have IBS rarely provides a new diagnosis or uncovers a different medical problem.
We generally recommend a few simple tests as part of the initial evaluation of a patient with symptoms of IBS (as long as the studies have not recently been performed elsewhere). These tests include simple laboratory tests, many of which can be done with a single blood sample, such as red and white blood cell counts and tests to measure blood sugar, kidney function, and electrolytes in the blood. For patients who have severe symptoms of constipation, blood testing for thyroid disorders is reasonable, and for patients who have persistent diarrhea, checking the erythrocyte sedimentation rate (ESR) is a simple way to look for evidence of inflammation in the body (an abnormal ESR will be seen in patients who have IBD but not in those who have IBS). In addition, patients who have persistent diarrhea will be asked to collect stool samples with a simple specially designed kit. These samples will be checked for white blood cells (fecal leukocytes). If that test is positive, the stool samples should be sent for further tests, to check for the presence of bacteria or parasites that might explain the diarrhea. (People who have persistent diarrhea who do not respond to standard IBS therapy should have their blood tested for celiac disease, because celiac disease can occasionally mimic IBS.)
When patients have symptoms that are severe enough or confusing enough, or if symptoms fail to respond to what is thought to be appropriate treatment, the doctor will want to have a look inside the intestinal tract. Direct visual examination can be performed using either a flexible sigmoidoscope or a colonoscope (see Chapter 8). Both of these devices are lighted tubes with a miniature camera attached.
During the initial office visit, your doctor will be generating what is called a “differential diagnosis,” a list of medical conditions that could account for your symptoms. One reason for preparing for the initial visit and giving your doctor as much information as possible is that the list of disorders that can cause symptoms of abdominal pain and altered bowel habits is long. Table 7.3 provides just some of these possibilities. As the interview progresses and the physical examination is performed, the doctor is able to narrow the list because of the presence or absence of certain information and findings. In the case of a patient who has IBS, when the interview establishes the chronic nature of the symptoms and the physical examination appears to rule out organic disease, the differential diagnosis narrows considerably. In most cases, given enough information, the diagnosis of IBS can be made at the time of the first office visit.
Table 7.3. A Brief Differential Diagnosis of IBS Symptoms
Inflammatory bowel disease |
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Crohn’s disease |
Ulcerative colitis |
Microscopic colitis |
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Collagenous colitis |
Lymphocytic colitis |
Malabsorption |
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Celiac disease |
Small intestine bacterial overgrowth |
Tropical sprue |
Lymphoma |
Pancreatic insufficiency |
Amyloidosis |
Lactose, fructose, or gluten intolerance |
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Food sensitivities |
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Food allergies |
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Urologic sources of pain |
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Kidney stones (nephrolithiasis) |
Prostatitis |
Interstitial cystitis |
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Gynecologic sources of pain |
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Ovarian cysts |
Uterine fibroids |
Endometriosis |
Pelvic inflammatory disease |
Interstitial cystitis |
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Other disorders |
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Colonic inertia |
Mastocytosis |
Viral gastroenteritis |
HIV enteropathy |
Diabetic diarrhea |
Whipple’s disease |
Intestinal ischemia |
Eosinophilic enteritis |
Cancer |
Pelvic floor dysfunction |
Early diagnosis of IBS is an important goal, because it allows appropriate treatment to begin right away and minimizes expensive, time-consuming, and sometimes risky testing. In several good research studies, patients diagnosed with IBS based on a normal physical examination and a predefined definition of IBS were followed for several years. In these studies, the accuracy of the diagnosis was more than 97 percent. In one study, patients were followed for nearly 30 years, and the initial diagnosis of IBS remained accurate during that long follow-up period. The high accuracy of making a diagnosis resulting from a simple definition and a careful history and physical examination should be reassuring to people who think they may have IBS. Although this combination of definition, history, and examination for diagnosis is not perfect, in the few cases where a patient had not been correctly diagnosed with IBS, nothing serious was missed, such as colon cancer or inflammatory bowel disease. These results support our contention that IBS can be safely, efficiently, and accurately diagnosed in the office.
• The average patient who has IBS sees three different doctors during three years before the diagnosis of IBS is made.
• IBS can be accurately diagnosed by using a formal definition of IBS (the Rome criteria), taking a careful medical history, performing a thorough physical examination, and using selected diagnostic tests, as appropriate.
• IBS cannot be diagnosed by a CT scan, an ultrasound, or a colonos-copy. Because IBS is a functional bowel disorder, the GI tract may look normal but not function normally.
• For patients who have IBS with chronic symptoms, repeated testing is seldom helpful and rarely leads to a change in diagnosis or treatment.
Improvement with defecation, and/or