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Irritable Bowel Syndrome (IBS)

What is Irritable Bowel Syndrome (IBS)? Irritable bowel syndrome (IBS) is a chronic, functional condition of the gastrointestinal system that is described by a group of symptoms affecting the large intestine. IBS is a common cause of gastrointestinal discomfort, affecting over 10% of the population, predominantly young female adults.

What is the cause of IBS?

The pathophysiology behind IBS has not been definitively described, but is thought to be influenced by several factors:

  • Disordered gut-brain communication causing problems in gut motility, visceral hypersensitivity, and abnormal CNS processing.
  • Genetic predisposition.
  • Changes in the gastrointestinal microbiome.
  • Dysfunctional mucosal and immune function.

Risk factors for IBS include:

  • Female gender.
  • Acute GI infection.
  • Psychological co-morbidity.
  • Co-morbid fibromyalgia, chronic fatigue syndrome, or GERD.
  • Food intolerances.

Symptoms of IBS

Common symptoms of IBS include:

  • Abdominal cramps
  • Changes in bowel habits

IBS can be classified by changes in bowel habits. IBS-D refers to the type with diarrhea as a predominant symptom, IBS-C for symptoms with constipation, and IBS-M for a mixed stool pattern.

The diagnosis of IBS requires abdominal pain with an alteration in stool pattern or frequency for at least six months. As IBS typically manifests without alarm symptoms, progression of symptoms, the onset of symptoms after the age of 50, weight loss, rectal bleeding, and iron deficiency, should prompt further testing.

Source: Ford, A. C., Sperber, A. D., Corsetti, M., & Camilleri, M. (2020). Irritable bowel syndrome. The Lancet, 396(10263), 1675–1688. https://doi.org/10.1016/s0140-6736(20)31548-8