The aetiology of IBS is multifactorial and is thought to involve the interaction of genetic, environmental, and psychosocial factors. IBS poses a significant burden on the affected individuals and the healthcare system.

Diagnosis

The diagnosis of IBS is based on the characteristic symptoms and the exclusion of organic diseases. The Rome IV criteria are widely used for the diagnosis of IBS. According to these criteria, a patient must have recurrent abdominal pain on average at least one day per week in the last three months, associated with two or more of the following symptoms: improvement with defecation, onset associated with a change in stool frequency, or onset associated with a change in stool form.

The diagnosis of IBS should be considered in patients who present with these symptoms, and the evaluation should focus on ruling out organic diseases such as inflammatory bowel disease, celiac disease, and colorectal cancer.

Management

The management of IBS is based on the individual's symptoms and the severity of the condition. The treatment options include lifestyle modifications, dietary changes, pharmacotherapy, and psychological interventions. Lifestyle modifications include regular exercise, stress reduction, and adequate sleep. Patients with IBS should also avoid trigger foods such as lactose, fructose, and fatty foods. A low FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diet may also be beneficial in some patients.

Pharmacotherapy for IBS includes several classes of drugs such as antispasmodics, laxatives, and antidepressants. Antispasmodics such as hyoscine and dicyclomine can provide relief from abdominal pain and bloating. Laxatives such as polyethylene glycol can be used in patients with constipation-predominant IBS.

Antidepressants such as tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs) can be beneficial in patients with IBS with predominant pain or diarrhoea. Cholestyramine, loperamide and antihistamines (for food allergy) are also used. Psychological interventions such as cognitive-behavioural therapy (CBT) and hypnotherapy have also shown promise in the management of IBS. CBT focuses on identifying and changing negative thoughts and behaviours that contribute to the symptoms of IBS. Hypnotherapy involves inducing a state of relaxation and using suggestion to improve the symptoms of IBS.

Recent advances

Recent advances in the understanding of IBS include the role of gut microbiota, visceral hypersensitivity, and immune activation. Dysbiosis, or an imbalance in the gut microbiota, has been implicated in the pathogenesis of IBS. Alterations in the gut microbiota can lead to increased intestinal permeability, inflammation, and changes in motility. Several studies have shown that probiotics and prebiotics can improve the symptoms of IBS.

Visceral hypersensitivity, or increased sensitivity of the gut to distension, has also been implicated in the pathogenesis of IBS. This hypersensitivity can lead to increased pain and discomfort in response to normal gut stimuli. Studies have shown that medications such as tricyclic antidepressants and SSRIs can reduce visceral hypersensitivity and improve the symptoms of IBS. Immune activation has also been implicated in the pathogenesis of IBS.

References available on request.