Despite the best efforts of clinicians, certain diseases are difficult to diagnose. Many conditions share common symptoms like inflammation, diarrhea, nausea, headache, constipation, and more, leaving physicians to make educated guesses based on the probability of given diseases. Under this framework, physicians are more inclined to diagnose common yet relatively less harmful diseases first, then correct their diagnosis to a more serious disease later if necessary.
While physicians are generally skilled at separating symptom clusters which occur in different diseases, irritable bowel syndrome (IBS) is a particularly common misdiagnosis due to the breadth of its symptoms and its prevalence as a disease. When added to the fact that IBS is nonfatal and its treatments are typically easy to tolerate, doctors are at high risk of making an incorrect IBS diagnosis; an IBS diagnosis is unlikely to stigmatize the patient, and the diagnosis is unlikely to traumatize the patient inherently when compared to some other possible diagnoses. Unfortunately, an incorrect diagnosis of IBS can result in protracted treatment cycling which fails to treat the underlying non-IBS pathology, leaving patients to struggle with distressing and potentially dangerous symptoms.
Being an informed patient with an IBS diagnosis or other gastrointestinal pathology means staying abreast of the various conditions which may be mistaken for irritable bowel syndrome. Likewise, being a skilled practitioner means understanding the ways in which other diseases might present similarly to IBS in the clinic. Furthermore, both patients and physicians should reassess the IBS diagnostic process such that the right disease ends up being treated.
Understanding the Diagnosis Of IBS
IBS can be challenging to diagnose properly in part because it it is not a well-understood or easily identified disease. There are no blood tests for IBS, nor does visual examination or equipment-assisted imaging provide any answers. Furthermore, IBS symptoms have no single identifiable trigger, which means that they can appear to be transient and without cause or incorrectly associated with a benign stimulus like certain foods. This also leads to confident yet incorrect diagnoses, as corrective action like refraining from consuming suspected trigger foods may coincide with a long period without a flare up of IBS.
Without objective diagnostic methods, doctors are left to diagnose IBS using their own judgment, which they are trained to supplement with several clinical diagnostic rubrics. Like elsewhere in medicine, diagnostic rubrics for IBS are pioneered by clinicians, substantiated by research studies, and then refined and eventually replaced by subsequent cooperation between physicians and researchers. The original diagnostic rubric for IBS states that there are several core symptoms which always occur:
- Belly distention
- Pain that subsides after a bowel movement
- Frequent bowel movements
- Looser stools
- Pain during bowel movements
Since the publication of this rubric, a number of others have emerged, each of which has its own advantages and disadvantages, with some being better at proving IBS specifically and others more effective at ruling out other diseases. Physicians typically use the rubric they were trained with, barring hospital policy to use a specific rubric. Rubrics also place different weights on different symptoms; where mucus and the feeling of incomplete bowel evacuation may be core symptoms to one rubric, they may only be attendant symptoms to another. This inconsistency allows for a wide degree in variation of diagnostic practices.
The tests called for by these diagnostic guidelines are not consistently applied either. According to one study on IBS diagnosis, 0% of 149 patients were diagnosed using all of the tests required by the most recent guidelines. Even the most common tests—including a basic blood test, a chemistry panel, blood sedimentation rate testing, and a serum thyroxine assay—were inconsistently performed. The researchers found that only 42% had a basic blood test, and 41% underwent colon imaging. Because IBS is typically diagnosed via exclusion of other similar diseases, insufficient testing leaves a larger area for misdiagnoses to occur. Certain diseases might only show up on a blood test, whereas others might only show up via an imaging study. Other conditions like mental health disorders or illnesses which cause a minority of gastrointestinal symptoms might only be correctly diagnosed instead of IBS if a specific questionnaire regarding that condition was administered to the patient, a highly unlikely possibility if the patient is complaining predominantly of their gastrointestinal symptoms. Building a basic understanding of these alternative health conditions is necessary for clinicians who want to cut down on their misdiagnosis rate and patients who want to ensure their own diagnosis is correct.
Conditions Often Misdiagnosed as IBS
Diagnosing IBS correctly is difficult, and that difficulty spills over into making correct diagnoses of other diseases affecting the gastrointestinal tract. In the absence of biopsies or lab results confirming another condition, IBS is an easy go-to diagnosis for clinicians to make because of its transient symptoms, which tend to be of moderate severity. Thanks to the inherent ambiguity of the language that patients use to describe their issues to their doctors, complaints about gastrointestinal symptoms that aren’t severe enough to be viral and aren’t mild enough to be associated with a non-gastrointestinal disease are at high risk of misdiagnosis as IBS.
Inflammatory Bowel Diseases
Inflammatory bowel diseases (IBDs) like Crohn’s disease and ulcerative colitis are often initially misdiagnosed as IBS. IBDs are characterized by inflammation, bloating, gas, pain, and often rectal bleeding, all symptoms shared with IBS to some degree. These symptoms are accompanied by disturbances to the microbiome, a propensity for inflammatory episodes, and diminished quality of life. The reasons for misdiagnosis are simple: IBS symptoms often overlap with IBD symptoms, IBS can be comorbid with IBDs, and IBS is a much less serious diagnosis. In the event of a patient with both IBS and an IBD, it may be impossible for doctors to separate the symptoms of IBS from the symptoms of the IBD, especially if the IBD’s onset is relatively recent. Without a history of severe gastrointestinal issues, the diagnosis of IBS is more expedient.
Unfortunately, the differences between IBS and IBDs can often be difficult for clinicians to spot even when both are confirmed. However, unlike IBS, IBDs are clinically diagnosable with a variety of blood tests, biopsies, and imaging tests thanks to their telltale inflammation and physical damage to the gastrointestinal tract. Notably, IBDs improve with pharmaceutical treatments targeted at the gut, whereas IBS may not. It’s easy to imagine that a patient could be diagnosed with IBS during the early development of their IBD and fruitlessly spend months or longer trying to treat it.
Due to the large degree of overlap between celiac disease and IBS symptoms, physicians diagnosing a patient with both conditions may fail to recognize the presence of celiac, focusing solely on the IBS diagnosis. This problem is widespread and may be complicated by coincidence of other pathologies which more strongly suggest IBS than a diagnosis of celiac disease. One study found that of 200 patients with IBS, 54 patients also had celiac disease that was diagnosable via a blood test. Notably, if these patients were initially diagnosed with IBS using a clinical rubric alone, they might never have received the blood test necessary to detect celiac disease, leaving them to suffer with celiac symptoms without understanding why. While the diagnostic history of these 54 patients is unknown, it’s likely that at least several of them faced an initial IBS diagnosis before their celiac disease was subsequently diagnosed after their symptoms failed to improve.
Additionally, patients with celiac disease may not have IBS whatsoever, but may receive a fundamentally incorrect diagnosis as the result of misattributed symptomatology and an absence of testing.
Gluten sensitivity is an increasingly common disorder in which patients experience indigestion, pain, bloating, and gas after consuming foods rich in gluten, such as bread and most starchy vegetables. Though gluten sensitivity is traditionally thought to primarily be a consequence of celiac disease, a new scientific understanding of gluten sensitivity has shown that it can occur independently of other disorders. Today, gluten sensitivity is increasingly associated with IBS, though inconsistently so within the dietary history of a single person. Therefore, a person with gluten sensitivity may or may not have IBS, but a person with IBS is more likely than a healthy control to have some degree of gluten sensitivity. This complicates diagnosis substantially. Because of its seemingly unpredictable gastrointestinal symptoms and transient flare-ups, gluten sensitivity is at high risk of being misdiagnosed as IBS in patients who do not have IBS and missed in patients who have comorbid IBS and gluten sensitivity.
As noted in a study connecting IBS to gluten sensitivity and IBDs, gluten sensitivity is prone to induce symptoms similar to IBS. This is the case whether the gluten sensitivity is associated with another pathology like celiac disease or whether it is in isolation. The consequences of gluten sensitivity misdiagnosed as IBS are clear: incorrectly diagnosed patients will continue to consume gluten and have flare-ups despite ongoing treatment for IBS. Treatment for IBS will do little to address the gastrointestinal intolerance of gluten, and patients will suffer.
Anxiety and Depression
Doctors have long thought that IBS has a psychiatric component. Indeed, most accounts of IBS consider anxious, depressive, and obsessive symptoms to be features of the condition. Whether these components cause IBS or are themselves caused by IBS is unclear, however, which places them at high risk of misdiagnosis. As found in one study from 2007, 46 of 95 patients diagnosed with depression and IBS experienced no IBS symptoms when their depression was in remission, suggesting that IBS symptom presence and severity are closely tied to psychiatric phenomena. Unfortunately, it also means that when the patients were having a depressive episode but complained predominantly to their physician about their gastrointestinal symptoms, their depression was likely to be missed even as IBS was identified.
Because depression manifests differently in different people, it’s already a disease at very high risk for misdiagnosis. Furthermore, depression and anxiety are very likely to be comorbid with IBS, even though their symptoms are not commonly understood to be as viscerally uncomfortable. Patients with anxiety may also have gastrointestinal systems which may either indicate IBS or be subclinical and not severe enough to truly meet diagnostic criteria for IBS. Given that patients are more likely to go to the doctor and complain about viscerally discomforting pathologies than psychological distress, however, IBS is an easy diagnosis to make when it’s masking emotional illnesses which are the root cause of symptoms. In fact, the same 2007 study mentioned above found that depression, anxiety, and IBS held a correlation of 54%—an astronomically high percentage of correlation between phenomena in the world of biomedical science. The growing medical consensus on IBS is thus that it is a predominantly psychosomatic disorder that may be inseparable from these other common psychiatric conditions. The takeaway is that patients diagnosed with IBS who also have low mood, excessive worry, or other symptoms consistent with depression or anxiety should seriously consider getting a second opinion.
Stomach and Colon Cancer
Of the diagnoses that an IBS diagnosis can mask, one of the most serious is that of stomach cancer. Stomach cancer is characterized by heartburn, nausea, blood in stools, indigestion, pain, diarrhea, loss of appetite, and constipation. This condition is difficult to diagnose under ideal conditions and often does not present itself symptomatically until it is in an advanced stage, at which point survival rates are extremely low; less than 10% of patients survive more than five years upon late stage diagnosis. Nonetheless, if the cancer is caught early and action is quickly taken, stomach cancer is survivable and even curable with the help of surgery. Under these conditions, an incorrect IBS diagnosis could easily be fatal, however.
Notably, the symptoms which differentiate true IBS from stomach cancer are likely the associated emotional disorders; stomach cancer pre-diagnosis is not associated with any emotional disturbances like anxiety, or depression, whereas IBS is. If an IBS diagnosis is made without a brief mental health inventory, blood test, or biopsy, there’s a chance that it could be hiding a much more pernicious disease.
Colon cancer may be yet another serious disease that may be hiding beneath an incorrect IBS diagnosis. Much like with stomach cancer, colon cancer’s symptoms include bloody stools, pain, fatigue, indigestion, and discomfort. Bloody stools are typically the symptom which doctors would use to easily differentiate IBS from a more serious illness like colorectal cancer, which means that patients going to the doctor before experiencing that symptom may be misdiagnosed. Patients with inflammatory bowel diseases are at a much higher risk of colon cancer, which means that an initial missed diagnosis or misdiagnosis could cause physicians to miss critical signs of subsequent cancer.
Colon cancer is more treatable than stomach cancer, however. Patients who are misdiagnosed with IBS may have a greater chance of survival thanks to a plethora of surgical and chemotherapy options which are effective enough to rescue patients with somewhat late diagnoses. Furthermore, unlike with stomach cancer, failure to make a colorectal cancer diagnosis is likely to be addressed in a subsequent screen as part of general adult health maintenance for patients that are at risk.
Toward Diagnostic Accuracy
Most of the diseases that are commonly misdiagnosed as IBS are chronic and unlikely to respond to IBS treatments. Likewise, IBS itself is chronic and may not always respond to treatments specifically targeted at it after a correct diagnosis. Patients and doctors are thus left in a difficult position where they are forced to act on incomplete and potentially incorrect information under the best of circumstances. If an incorrect IBS diagnosis—or missed diagnosis in the presence of comorbid conditions—prevents treatment of another disease that can carry permanent damage, the chance of long-term consequences is very high. In the case of Crohn’s disease, for example, scarring to the gastrointestinal tract may be impossible to repair even after the diagnosis is rectified, causing chronic difficulty with bowel movements, nutrient absorption, and comfortable digestion.
Not all hope is lost, however. Diligence and awareness of IBS’ common position as a first and incorrect diagnosis can mitigate the danger of prolonged misdiagnosis. This means that patients need to ensure that their physicians have ruled out the most common misdiagnoses after receiving an IBS diagnosis. Patients also need to remain vigilant even after they leave the clinic; if patients receive an IBS diagnosis and their symptoms do not reside quickly, they must follow up with their practitioner immediately. Doing so will minimize the damage caused by a misdiagnosis and get treatment on the right track. Rather than hoping for a correct initial diagnosis, patients will need to take an active role in their care.
For their part, physicians need to use differential diagnostic techniques that take into account the possibility of comorbidities or non-IBS root causes. Following up with the patient regularly will also help to confirm or refute the initial diagnosis. Likewise, physicians must endeavour to be consistent and comprehensive in their diagnostic practices of IBS lest they damage the therapeutic relationship and tarnish their reputations. With a strong therapeutic alliance and careful application of diagnostic guidelines for a panorama of diseases, moving beyond systemic IBS scapegoating is possible.
Karling P, Danielsson A, Adolfsson R, Norrback KF. 2007. No difference in symptoms of irritable bowel syndrome between healthy subjects and patients with recurrent depression in remission. Neurogastroenterol Motil. 19:896–904. http://europepmc.org/abstract/MED/17973640
Manning AP, Thompson WG, Heaton KW, Morris AF. 1978. Towards positive diagnosis of the irritable bowel. Br Med J. 2:653–654. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1607467/
Yawn BP, Lydick E, Locke GR, Wollan PC, Bertram SL, et al. 2001. Do published guidelines for evaluation of Irritable Bowel Syndrome reflect practice? BMC Gastroenterol. 1:11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC59674/
Zwolińska-Wcisło M, Galicka-Latała D, Rozpondek P, Rudnicka-Sosin L, Mach T. 2009. Frequency of celiac disease and irritable bowel syndrome coexistance and its influence on the disease course. Przegl Lek. 66:126–129. http://europepmc.org/abstract/med/19689036