bowel disease. the criteria for selecting tests and investigations also depends on the level of available medical resources. rome criteria the rome criteria are consensus guidelines, initially released in 1994 and updated periodically since then. these may pertain more closely to clinical trials as in practice, patient symptoms may vary considerably. the rome iv criteria (2016) for ibs include recurrent abdominal pain, on average, at least one day/week in the last three months, associated with additional stool- or defecation-related criteria. the algorithm may include additional tests to guard against misdiagnosis of other diseases as ibs. such "red flag" symptoms may include weight loss, gastrointestinal bleeding, anemia, or nocturnal symptoms. however, red flag conditions may not always contribute to accuracy in diagnosis; for instance, as many as 31% of people with ibs have blood in their stool, many possibly from hemorrhoidal bleeding. the diagnostic algorithm identifies a name that can be applied to the person's condition based on the combination of symptoms of diarrhea, abdominal pain, and constipation. for example, the statement "50% of returning travellers had developed functional diarrhea while 25% had developed ibs" would mean half the travellers had diarrhea while a quarter had diarrhea with abdominal pain. while some researchers believe this categorization system will help physicians understand ibs, others have questioned the value of the system and suggested all people with ibs have the same underlying disease but with different symptoms. differential diagnosis colon cancer, inflammatory bowel disease, thyroid disorders (hyperthyroidism or hypothyroidism), and giardiasis can all feature abnormal defecation and abdominal pain. less common causes of this symptom profile are carcinoid syndrome, microscopic colitis, bacterial overgrowth, and eosinophilic gastroenteritis; ibs is, however, a common presentation, and testing for these conditions would yield low numbers of positive results, so it is considered difficult to justify the expense. conditions that may present similarly include celiac disease, bile acid malabsorption, colon cancer, and dyssynergic defecation. ruling out parasitic infections, lactose intolerance, small intestinal bacterial overgrowth, and celiac disease is recommended before a diagnosis of irritable bowel syndrome is made. an upper endoscopy with small bowel biopsies is necessary to identify the presence of celiac disease. an ileocolonoscopy with biopsies is useful to exclude crohn's disease and ulcerative colitis (inflammatory bowel disease). some people, managed for years for ibs, may have non-celiac gluten sensitivity (ncgs). gastrointestinal symptoms of ibs are clinically indistinguishable from those of ncgs, but the presence of any of the following non-intestinal manifestations suggest a possible ncgs: headache or migraine, "foggy mind", chronic fatigue, fibromyalgia, joint and muscle pain, leg or arm numbness, tingling of the extremities, dermatitis (eczema or skin rash), atopic disorders, allergy to one or more inhalants, foods or metals (such as mites, graminaceae, parietaria, cat or dog hair/dander, shellfish, or nickel), depression, anxiety, anemia, iron-deficiency anemia, folate deficiency, asthma, rhinitis, eating disorders, neuropsychiatric disorders (such as schizophrenia, autism, peripheral neuropathy, ataxia, attention deficit hyperactivity disorder) or autoimmune diseases. an improvement with a gluten-free diet of immune-mediated symptoms, including autoimmune diseases, once having reasonably ruled out celiac disease and wheat allergy, is another way to realize a differential diagnosis. investigations investigations are performed to exclude other conditions: stool microscopy and culture (to exclude infectious conditions) blood tests: full blood examination, liver function tests, erythrocyte sedimentation rate, and serological testing for coeliac disease abdominal ultrasound (to exclude gallstones and other biliary tract diseases) endoscopy and biopsies (to exclude peptic ulcer disease, coeliac disease, inflammatory bowel disease, and malignancies) hydrogen breath testing (to exclude fructose and lactose malabsorption) misdiagnosis people with ibs are at increased risk of being given inappropriate surgeries such as appendectomy, cholecystectomy, and hysterectomy due to being misdiagnosed as other medical conditions. some common examples of misdiagnosis include infectious diseases, coeliac disease, helicobacter pylori, parasites (non-protozoal). the american college of gastroenterology recommends all people with symptoms of ibs be tested for coeliac disease. bile acid malabsorption is also sometimes missed in people with diarrhea-predominant ibs. sehcat tests suggest around 30% of people with d-ibs have this condition, and most respond to bile acid sequestrants. comorbidities several medical conditions, or comorbidities, appear with greater frequency in people with ibs. neurological/psychiatric: a study of 97,593 individuals with ibs identified comorbidities such as headache, fibromyalgia, and depression. ibs occurs in 51% of people with chronic fatigue syndrome and 49% of people with fibromyalgia, and psychiatric disorders occur in 94% of people with ibs. channelopathy and muscular dystrophy: ibs and functional gi diseases are comorbidities of genetic channelopathies that cause cardiac conduction defects and neuromuscular dysfunction, and result also in alterations in gi motility, secretion, and sensation. similarly, ibs and fbd are highly prevalent in myotonic muscle dystrophies. digestive symptoms may be the first sign of dystrophic disease and may precede the musculo-skeletal features by up to 10 years. inflammatory bowel disease: ibs may be marginally associated with inflammatory bowel disease. researchers have found some correlation between ibs and ibd, noting that people with ibd experience ibs-like symptoms when their ibd is in remission. a three-year study found that patients diagnosed with ibs were 16.3 times more likely to be diagnosed with ibd during the study period, although this is likely due to an initial misdiagnosis. abdominal surgery: people with ibs were at increased risk of having unnecessary gall bladder removal surgery not due to an increased risk of gallstones, but rather to abdominal pain, awareness of having gallstones, and inappropriate surgical indications. these people also are 87% more likely to undergo abdominal and pelvic surgery and three times more likely to undergo gallbladder surgery. also, people with ibs were twice as likely to undergo hysterectomy. endometriosis: one study reported a statistically significant link between migraine headaches, ibs, and endometriosis. other chronic disorders: interstitial cystitis may be associated with other chronic pain syndromes, such as irritable bowel syndrome and fibromyalgia. the connection between these syndromes is unknown. management a number of treatments have been found to be effective, including fiber, talk therapy, antispasmodic and antidepressant medication, and peppermint oil. fodmap fodmaps are short-chain carbohydrates that are poorly absorbed in the small intestine. a 2018 systematic review found that although there is evidence of improved ibs symptoms with a low fodmap diet, the evidence is of very low quality. symptoms most likely to improve on this type of diet include urgency, flatulence, bloating, abdominal pain, and altered stool output. one national guideline advises a low fodmap diet for managing ibs when other dietary and lifestyle measures have been unsuccessful. the diet restricts various carbohydrates which are poorly absorbed in the small intestine, as well as fructose and lactose, which are similarly poorly absorbed in those with intolerances to them. reduction of fructose and fructan has been shown to reduce ibs symptoms in a dose-dependent manner in people with fructose malabsorption and ibs. fodmaps are fermentable oligo-, di-, monosaccharides and polyols, which are poorly absorbed in the small intestine and subsequently fermented by the bacteria in the distal small and proximal large intestine. this is a normal phenomenon, common to everyone. the resultant production of gas potentially results in bloating and flatulence. although fodmaps can produce certain digestive discomfort in some people, not only do they not cause intestinal inflammation, but they help avoid it, because they produce beneficial alterations in the intestinal flora that contribute to maintaining the good health of the colon. fodmaps are not the cause of irritable bowel syndrome nor other functional gastrointestinal disorders, but rather a person develops symptoms when the underlying bowel response is exaggerated or abnormal. a low-fodmap diet consists of restricting them from the diet. they are globally trimmed, rather than individually, which is more successful than for example restricting only fructose and fructans, which are also fodmaps, as is recommended for those with fructose malabsorption. a low-fodmap diet might help to improve short-term digestive symptoms in adults with irritable bowel syndrome, but its long-term follow-up can have negative effects because it causes a detrimental impact on the gut microbiota and metabolome. it should only be used for short periods of time and under the advice of a specialist. a low-fodmap diet is highly restrictive in various groups of nutrients and can be impractical to follow in the long-term. more studies are needed to assess the true impact of this diet on health. in addition, the use of a low-fodmap diet without verifying the diagnosis of ibs may result in misdiagnosis of other conditions such as celiac disease. since the consumption of gluten is suppressed or reduced with a low-fodmap diet, the improvement of the digestive symptoms with this diet may not be related to the withdrawal of the fodmaps, but of gluten, indicating the presence of unrecognized celiac disease, avoiding its diagnosis and correct treatment, with the consequent risk of several serious health complications, including various types of cancer. fiber some evidence suggests soluble fiber supplementation (e.g., psyllium/ispagula husk) is effective. it acts as a bulking agent, and for many people with ibs-d, allows for a more consistent stool. for people with ibs-c, it seems to allow for a softer, moister, more easily passable stool. however, insoluble fiber (e.g., bran) has not been found to be effective for ibs. in some people, insoluble fiber supplementation may aggravate symptoms. fiber might be beneficial in those who have a predominance of constipation. in people who have ibs-c, soluble fiber can reduce overall symptoms but will not reduce pain. the research supporting dietary fiber contains conflicting small studies complicated by the heterogeneity of types of fiber and doses used. one meta-analysis found only soluble fiber improved global symptoms of irritable bowel, but neither type of fiber reduced pain. an updated meta-analysis by the same authors also found soluble fiber reduced symptoms, while insoluble fiber worsened symptoms in some cases. positive studies have used 10–30 grams per day of ispaghula (psyllium). one study specifically examined the effect of dose, and found 20 g of ispaghula (psyllium) were better than 10 g and equivalent to 30 g per day. physical activity recent studies have demonstrated the potential beneficial effects of physical activity on irritable bowel syndrome. some randomised controlled trials (rcts) have demonstrated a beneficial effect of physical activity on ibs symptoms. three rcts showed a significant improvement in irritable bowel syndrome – severity scoring system, while 1 rct showed a significant improvement only in symptoms of constipation. in light of this, the latest british society of gastroenterology guidelines on the management of ibs have stated that all patients with ibs should be advised to take regular exercise (strong recommendation, weak certainty evidence), whereas the american college of gastroenterology guidelines have suggested with a lower certainty of evidence. exercise is medicine recently provided simple practical indications based on world health organization guidelines, which should be followed when physicians prescribing exercise training. as shown by the previous studies, a good physical activity prescription during the visit could significantly improve patients’ adherence and, consequently, lead to a significant clinical benefit for symptoms of irritable bowel syndrome. medication medications that may be useful include antispasmodics such as dicyclomine and antidepressants. both h1-antihistamines and mast cell stabilizers have shown efficacy in reducing pain associated with visceral hypersensitivity in ibs. serotonergic agents a number of 5-ht3 antagonists or 5-ht4 agonists were proposed clinically to treat diarrhea-predominant ibs and constipation-predominant ibs, respectively. however, severe side effects have resulted in its withdrawal by food and drug administration and are now prescribed under emergency investigational drug protocol. other 5-ht receptor subtypes, such as 5-ht7 receptor, have yet to be developed. laxatives for people who do not adequately respond to dietary fiber, osmotic laxatives such as polyethylene glycol, sorbitol, and lactulose can help avoid "cathartic colon" which has been associated with stimulant laxatives. lubiprostone is a gastrointestinal agent used for the treatment of constipation-predominant ibs. antispasmodics the use of antispasmodic drugs (e.g., anticholinergics such as hyoscyamine or dicyclomine) may help people who have cramps or diarrhea. a meta-analysis by the cochrane collaboration concludes if seven people are treated with antispasmodics, one of them will benefit. antispasmodics can be divided into two groups: neurotropics and musculotropics. musculotropics, such as mebeverine, act directly at the smooth muscle of the gastrointestinal tract, relieving spasm without affecting normal gut motility. since this action is not mediated by the autonomic nervous system, the usual anticholinergic side effects are absent. the antispasmodic otilonium may also be useful. discontinuation