Irritable Bowel Syndrome

Question 1

How common is it?

Answer 1

10-20% of population

Question 2

Who does it affect?

Answer 2

Age at onset <40 yrs; M:F ratio = 1:2.

Question 3

What causes it?

Answer 3

IBS denotes a mixed group of abdominal symptoms for which no organic cause can be found. Most are probably due to disorders of intestinal motility or enhanced visceral perception (the ‘brain-gut’ axis).

Question 4

What risk factors are there?

Answer 4

Young, female, family history.

Question 5

How does it present?

Answer 5

Symptoms

• Diagnosed if: Abdominal pain (or discomfort) relieved by defecation or associated with altered stool form or bowel frequency (constipation and diarrhoea may alternate and there are >2 of: urgency, incomplete evacuation, abdominal bloating/distension, mucous PR, worsening of symptoms after food.
• Symptoms are chronic (>6 months) and exacerbated by stress, menstruation or gastroenteritis.

Signs
- Examination often normal, but general abdo tenderness is common. Insufflation of air during sigmoidoscopy (not usually needed) may reproduce the pain.

Question 6

What other conditions may present similarly?

Answer 6

Think of other diagnoses if: Age >40 yrs (esp male); history of <6 months, anorexia, weight loss, waking at night with pain/diarrhoea, mouth ulcers, abnormal CRP/ESR/Hb/coealic serology.

Investigate PR bleeding urgently.

Question 7

Investigations?

Answer 7

Make a positive diagnosis (OPPOSITE) but aso try to exclude other diagnoses, so:

• If history is classic – FBC, ESR, CRP, LFT and coealiac serology sufficient.
• If >50yrs or any marker or organic disease (inc temp, blood pr, weight loss): colonoscopy.
• Have a low threshold for referring if family history of ovarian or bowel cancer.
• Excluding ovarian ca may need serum CA-125.
• If diarrhoea prominent do: LFT, stool culture, B12/folate, anti-endomysial antibodies, TSH, consider referral ± barium follow-through (if symptoms suggest small bowel disease) ± rectal biopsy.

Further investigations guided by symptoms:

• Upper GI endoscopy (dyspepsia, reflux) or small bowel radiology (Crohn’s).
• Duodenal biopsy (coeliac disease)
• Giardia ests
• ERCP (chronic pancreatitis) or MRCP if active pancreatitis.
• Transit studies and anorectal physiological studies

Question 8

Treatments?

Answer 8

• Treatment generally ineffective.
• Explanation and reassurance vital.
• Food intolerance generally not thought of as cause of IBS but ensure a healthy balanced diet.
• Further treatment depends on which symptoms predominate:
• Constipation – diet. Bisacodyl, sodium picosulfate, ispaghula.
• Diarrhoea – bulking agent (loperamide) after each loose stool.
• Colic/bloating – Oral antispasmodics.
• Psychological.