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Key Clinical Updates in Irritable Bowel Syndrome

Peppermint oil may be useful to relieve global IBS symptoms and abdominal pain.

Probiotics are not recommended for IBS treatment.

Lacy BE et al. Am J Gastroenterol. [PMID: 33315591]

ESSENTIALS OF DIAGNOSIS

  • Chronic functional disorder characterized by abdominal pain with alterations in bowel habits.

  • Symptoms usually begin in late teens to early twenties.

  • Limited evaluation to exclude organic causes of symptoms.

GENERAL CONSIDERATIONS

The functional GI disorders are characterized by a variable combination of chronic or recurrent GI symptoms not explicable by the presence of structural or biochemical abnormalities. Several clinical entities are included under this broad rubric, including chest pain of unclear origin (noncardiac chest pain), functional dyspepsia, and biliary dyskinesia (sphincter of Oddi dysfunction). There is a large overlap among these entities. For example, over 50% of patients with noncardiac chest pain and over one-third with functional dyspepsia also have symptoms compatible with IBS. In none of these disorders is there a definitive diagnostic study. Rather, the diagnosis is a subjective one based on the presence of a compatible profile and the exclusion of similar disorders.

IBS can be defined, therefore, as an idiopathic clinical entity characterized by chronic (more than 3 months) abdominal pain that occurs in association with altered bowel habits. These symptoms may be continuous or intermittent. The 2016 Rome IV consensus definition of IBS is recurrent abdominal pain that occurs an average of at least 1 day/week and is associated with two or more of the following three features: (1) related to defecation (relief or worsening), (2) associated with a change in frequency of stool, or (3) associated with a change in form (appearance) of stool. Other symptoms supporting the diagnosis include abnormal stool frequency; abnormal stool form (lumpy or hard; loose or watery); abnormal stool passage (straining, urgency, or feeling of incomplete evacuation); and abdominal bloating or a feeling of abdominal distention.

Patients may have other somatic or psychological complaints such as dyspepsia, heartburn, chest pain, headaches, fatigue, myalgias, urologic dysfunction, gynecologic symptoms, anxiety, or depression.

The disorder is a common problem presenting to both gastroenterologists and primary care physicians. Up to 5% of adults have symptoms compatible with the diagnosis, but most never seek medical attention. Approximately two-thirds of patients with IBS are women.

PATHOGENESIS

A. Abnormal Motility

A variety of abnormal myoelectrical and motor abnormalities have been identified in the colon and small intestine. In some cases, these are temporally correlated with episodes of abdominal pain or emotional stress. Differences between patients with constipation-predominant (slow intestinal transit or pelvic floor dyssynergia) and diarrhea-predominant (rapid intestinal transit, bile acid malabsorption) syndromes are reported.

B. Visceral Hypersensitivity

Patients often have a lower visceral pain threshold, reporting abdominal pain at ...

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