Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by abdominal pain and/or discomfort that resolves after a bowel movement.

These symptoms are accompanied by a change in the frequency and consistency of stool and are combined with at least two persistent symptoms of bowel dysfunction:

• change in stool frequency (more than 3 times a day or less than 3 times a week);
• changes in stool consistency (lumpy, dense stools or watery stools);
• changes in the act of defecation;
• imperative urges;
• a feeling of incomplete bowel movement;
• the need for additional effort during defecation;
• the release of mucus with feces;
• bloating, flatulence;
• rumbling in the stomach.

The duration of these disorders should be at least 12 weeks during the last 12 months. Among the disorders of the act of defecation, particular importance is attached to imperative urges, tenesmus, a feeling of incomplete emptying of the intestines, additional efforts during defecation (Rome criteria II).

The cause is unknown and the pathophysiology is not fully understood. Diagnosis is clinical. Treatment is symptomatic, consisting of dietary nutrition and drug therapy, including anticholinergic drugs and serotonin receptor activators.

Irritable bowel syndrome is a diagnosis of exclusion, i.e. its establishment is possible only after excluding organic diseases.

ICD-10 code

K58 Irritable bowel syndrome.

Epidemiology of irritable bowel syndrome

Irritable bowel syndrome is especially widespread in industrialized countries. According to world statistics, 30 to 50% of patients who visit gastroenterology offices suffer from irritable bowel syndrome; it is estimated that 20% of the world's population has symptoms of irritable bowel syndrome. Only 1/3 of patients seek medical help. Women get sick 2-4 times more often than men.

After 50 years, the ratio of men to women approaches 1:1. The occurrence of the disease after 60 years is questionable.

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What causes irritable bowel syndrome?

The cause of irritable bowel syndrome (IBS) is unknown. No pathological cause has been found. Emotional factors, diet, medications, or hormones may accelerate and aggravate gastrointestinal manifestations. Some patients experience anxiety states (especially panic, major depressive syndrome, and somatization syndrome). However, stress and emotional conflict do not always coincide with the onset of the disease and its relapse. Some patients with irritable bowel syndrome exhibit symptoms defined in the scientific literature as symptoms of atypical illness behavior (i.e., they express emotional conflict in the form of complaints of gastrointestinal disorders, usually abdominal pain). The physician examining patients with irritable bowel syndrome, especially those resistant to treatment, should explore unresolved psychological issues, including the possibility of sexual or physical abuse.

There are no persistent motility disorders. Some patients have a gastrocolic reflex disorder with delayed, prolonged colonic activity. This may be accompanied by a delay in gastric evacuation or a motility disorder of the jejunum. Some patients do not have objectively proven disorders, and in cases where disorders have been identified, there may be no direct correlation with symptoms. Passage through the small intestine is variable: sometimes the proximal segment of the small intestine shows hyperreactivity to food or to parasympathomimetics. Studies of the intracolonic pressure of the sigmoid colon have shown that functional retention of stool may be associated with hyperreactive segmentation of the haustra (i.e., increased frequency and amplitude of contractions). In contrast, diarrhea is associated with a decrease in motor function. Thus, strong contractions may from time to time accelerate or delay passage.

The excess mucus production that is often seen in irritable bowel syndrome is not due to mucosal damage. The reason is unclear, but may be related to cholinergic hyperactivity.

There is hypersensitivity to normal intestinal distension and dilation, and increased pain sensitivity with normal intestinal gas accumulation. The pain is likely due to abnormally strong contractions of intestinal smooth muscle or increased sensitivity of the intestine to distension. Hypersensitivity to the hormones gastrin and cholecystokinin may also be present. However, hormonal fluctuations do not correlate with symptoms. High-calorie foods may increase the magnitude and frequency of smooth muscle electrical activity and gastric motility. Fatty foods may cause a delayed peak in motor activity, which is significantly increased in irritable bowel syndrome. The first few days of menstruation may result in a transient increase in prostaglandin E2, which likely stimulates increased pain and diarrhea.

Symptoms of irritable bowel syndrome

Irritable bowel syndrome tends to begin in adolescents and young adults, with symptoms that are irregular and recurrent. Adult onset is not uncommon, but is not uncommon. Irritable bowel syndrome symptoms rarely occur at night, and may be triggered by stress or eating.

The clinical features of irritable bowel syndrome include abdominal pain associated with delayed stool movement, changes in stool frequency or consistency, bloating, mucus in the stool, and a feeling of incomplete evacuation of the rectum after stool. In general, the nature and location of pain, triggers, and stool patterns vary from patient to patient. Changes or deviations from usual symptoms suggest an intercurrent disorder, and these patients should undergo a full evaluation. Patients with irritable bowel syndrome may also have extraintestinal symptoms of irritable bowel syndrome (eg, fibromyalgia, headaches, dysuria, temporomandibular joint syndrome).

Two main clinical types of irritable bowel syndrome have been described.

In constipation-predominant irritable bowel syndrome (IBS-predominant irritable bowel syndrome), most patients have pain in more than one area of the colon, with periods of constipation alternating with normal bowel movements. The stools often contain clear or white mucus. The pain is colicky in nature or a constant, aching pain that may be relieved by defecation. Eating usually triggers symptoms. Bloating, frequent flatulence, nausea, dyspepsia, and heartburn may also occur.

Diarrhea-predominant irritable bowel syndrome is characterized by urgency diarrhea that occurs immediately during or after meals, especially when eating quickly. Nocturnal diarrhea is uncommon. Pain, bloating, and a sudden urge to defecate are typical, and fecal incontinence may develop. Painless diarrhea is uncommon and should prompt the physician to consider other possible causes (e.g., malabsorption, osmotic diarrhea).

Diagnosis of irritable bowel syndrome

Diagnosis of irritable bowel syndrome is based on characteristic intestinal manifestations, the nature and time of pain onset, and exclusion of other diseases during physical and standard instrumental examination. Diagnostic testing should be as rapid as possible in the case of risk factors ("alarm symptoms"): old age, weight loss, rectal bleeding, vomiting. The main diseases that can simulate irritable bowel syndrome include lactose intolerance, diverticular disease, drug-induced diarrhea, biliary tract disease, laxative abuse, parasitic diseases, bacterial enteritis, eosinophilic gastritis or enteritis, microscopic colitis, and inflammatory bowel disease.

Hyperthyroidism, carcinoid syndrome, medullary thyroid carcinoma, VIPoma, and Zollinger-Ellison syndrome are additional possible causes of diarrhea in patients with diarrhea. A bimodal age distribution of patients with inflammatory bowel disease allows for the assessment of groups of young and old patients. In patients over 60 years of age, ischemic colitis should be excluded. Patients with stool retention and no anatomical cause should be evaluated for hypothyroidism and hyperparathyroidism. If symptoms suggest malabsorption, sprue, celiac disease, and Whipple's disease, further evaluation is necessary. Stool retention in patients complaining of the need to strain during defecation (eg, pelvic floor dysfunction) requires evaluation.

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Anamnesis

Particular attention should be paid to the nature of the pain, bowel characteristics, family history, medications used and diet. It is also important to assess the patient's individual problems and emotional status. The doctor's patience and persistence are the keys to effective diagnosis and treatment.

Based on symptoms, the Rome criteria for the diagnosis of irritable bowel syndrome have been developed and standardized; the criteria are based on the presence of the following signs for at least 3 months:

1. abdominal pain or discomfort that is relieved by bowel movements or is associated with a change in stool frequency or consistency,
2. a bowel movement disorder characterized by at least two of the following: change in stool frequency, change in stool form, change in stool pattern, presence of mucus and bloating, or a feeling of incomplete evacuation of the rectum after defecation.

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Physical examination

In general, patients are in good condition. Abdominal palpation may reveal tenderness, particularly in the left lower quadrant, associated with palpation of the sigmoid colon. All patients should have a digital rectal examination, including a stool test for occult blood. In women, a pelvic examination (bimanual vaginal examination) helps to exclude ovarian tumors and cysts or endometriosis, which can simulate irritable bowel syndrome.

Instrumental diagnostics of irritable bowel syndrome

A flexible sigmoidoscopy should be performed. Insertion of the sigmoidoscope and air insufflation often cause intestinal spasm and pain. The mucosal and vascular pattern in irritable bowel syndrome is usually normal. Colonoscopy is preferable in patients over 40 years of age with complaints suggesting changes in the colon and especially in patients without previous symptoms of irritable bowel syndrome to exclude polyposis and colonic tumor. In patients with chronic diarrhea, especially elderly women, a mucosal biopsy can exclude possible microscopic colitis.

Many patients with irritable bowel syndrome tend to be over-diagnosed. In patients whose clinical picture meets the Rome criteria but who have no other symptoms or signs suggestive of another pathology, laboratory test results do not influence the diagnosis. If the diagnosis is in doubt, the following tests should be performed: complete blood count, ESR, blood chemistry (including liver function tests and serum amylase ), urinalysis, and thyroid-stimulating hormone levels.

Additional research

(Ultrasound, CG, barium enema, esophagogastroduodenoscopy, and small bowel radiography are also indicated if the diagnosis of irritable bowel syndrome is uncertain or if other symptoms and dysfunctions are detected. If structural changes in the small bowel are diagnosed, an H2 breath test is indicated. Stool culture or stool examination for helminthic and parasitic infestations is rarely positive in the absence of a history of previous travel or specific signs (e.g., fever, bloody diarrhea, acute onset of severe diarrhea).

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Intercurrent disease

The patient may develop other gastrointestinal symptoms that are not typical of irritable bowel syndrome, and the clinician should consider these complaints. Changes in symptoms (eg, location, nature, or intensity of pain; bowel habits; palpable constipation and diarrhea) and new signs or complaints (eg, nocturnal diarrhea) may suggest another disorder. New symptoms that require further investigation include new blood in the stool, weight loss, severe abdominal pain or unusual abdominal enlargement, steatorrhea or foul-smelling stools, fever, chills, persistent vomiting, hematemesis, symptoms that interfere with sleep (eg, pain, urgency), and persistent progressive deterioration. Patients over 40 years of age are more likely to develop medical disorders than younger patients.

Treatment of irritable bowel syndrome

Treatment of irritable bowel syndrome is symptomatic and palliative. Empathy and psychotherapy are of the utmost importance. The physician must explain the underlying causes and reassure the patient that there is no somatic pathology. This includes explaining the normal physiology of the intestine, paying particular attention to intestinal hypersensitivity, the influence of food or medication. Such explanations form the basis for prescribing regular, standard, but individual therapy. The prevalence, chronicity, and need for continued treatment should be emphasized.

Psychological stress, anxiety or mood changes require assessment and appropriate therapy. Regular physical activity helps reduce stress and improve bowel function, especially in patients with constipation.

Nutrition and Irritable Bowel Syndrome

In general, a normal diet should be maintained. Meals should not be excessively abundant, and eating should be slow and measured. Patients with abdominal distension and increased gas formation should limit or exclude the consumption of beans, cabbage, and other foods containing carbohydrates that are susceptible to intestinal microbial fermentation. Reducing the consumption of apples and grape juice, bananas, nuts, and raisins may also reduce flatulence. Patients with signs of lactose intolerance should reduce the consumption of milk and dairy products. Intestinal dysfunction may be caused by the intake of foods containing sorbitol, mannitol, or fructose. Sorbitol and mannitol are artificial sweeteners used in dietetic foods and chewing gum, while fructose is a common element of fruits, berries, and plants. Patients with postprandial abdominal pain may be advised to follow a low-fat, high-protein diet.

Dietary fibre can be effective because it absorbs water and softens stool. It is indicated for patients with constipation. Soft stool-forming substances can be used [e.g. raw bran, starting with 15 ml (1 tablespoon) at each meal, with increasing fluid intake]. Alternatively, hydrophilic mucilloid psyllium with two glasses of water can be used. However, excessive use of fibre can lead to bloating and diarrhoea. Therefore, the amount of fibre should be adapted to individual needs.

Drug treatment of irritable bowel syndrome

Drug treatment of irritable bowel syndrome is not recommended except for short-term use during periods of exacerbation. Anticholinergic drugs (eg, hyoscyamine 0.125 mg 30-60 minutes before meals) may be used as antispasmodics. The new selective M muscarinic receptor antagonists, including zamifenacin and darifenacin, have fewer cardiac and gastrointestinal side effects.

Serotonin receptor modulation may be effective. The 5HT4 receptor agonists tegaserod and prucalopride may be effective in patients with stool retention. 5HT4 receptor antagonists (eg, alosetron) may be of benefit to patients with diarrhea.

Patients with diarrhea may be given diphenoxylate 2.5-5 mg or loperamide 2-4 mg orally before meals. However, chronic use of antidiarrheal drugs is undesirable because of the development of tolerance to the drugs. In many patients, tricyclic antidepressants (eg, desipramine, imipramine, amitriptyline 50-150 mg orally once a day) reduce symptoms of constipation and diarrhea, abdominal pain, and flatulence. These drugs are thought to reduce pain through postregulatory activation of the spinal cord and cortical afferents from the intestine. Finally, certain essential oils may help relieve irritable bowel syndrome by promoting gas passage, relieving smooth muscle spasm, and reducing pain in some patients. Peppermint oil is the most commonly used agent in this group.

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