History and exam

Key diagnostic factors

common

Key risk factors include female sex, age <50 years, previous enteric infection, and history of physical or sexual abuse.

Generally cramping in nature and in the lower and/or mid-abdomen. Can be mild or severe.

There may be diarrhoea or more frequent soft stool, constipation, or alternating diarrhoea and constipation. The passage of stool relieves the abdominal pain.

This increases during the day and is not associated with nausea and vomiting. It is improved with defecation or passage of flatus.

There are no significant findings. Mild tenderness may be found in the right lower quadrant or left lower quadrant.

Other diagnostic factors

uncommon

Occurs when the patient is symptomatic and is not accompanied by blood.

This symptom is more prevalent in Asian populations.[10]

Risk factors

strong

Several studies have shown that a history of physical and/or sexual abuse is more common in patients with IBS than in patients with other gastrointestinal disorders. Abuse has been reported in 32% to 44% of patients with IBS.[20][21][22]

One meta-analysis found that PTSD is associated with an increased likelihood of IBS (pooled odds ratio 2.80, 95% CI 2.06 to 3.54, P <0.001).[31]

Symptoms of IBS can begin in adolescence or early adulthood. The onset of IBS in patients aged >50 years is unusual, and patients in this group need to be evaluated carefully for other aetiologies of their symptoms.[15][16]

There is a 2:1 female/male ratio among adults who seek help for symptoms of IBS.[14]

Symptoms of IBS may occur in up to 30% of patients following acute bacterial gastroenteritis.​[24][32]

The odds of having IBS increase (odds ratio 2.75) if a first-degree relative has IBS.[19]

weak

Stressful life events sometimes correlate with symptom exacerbation, but the nature of this link is unclear.​[2]​

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