IBS - definition
Irritable bowel syndrome (IBS) is a chronic condition characterised by abdominal pain associated with bowel dysfunction. The pain is often relieved by defecation and is sometimes accompanied by abdominal bloating. There are no structural abnormalities to explain the pain (it is a functional disorder)
IBS - criteria (6 months of?)
6 months of:
- Abdominal pain or discomfort
- Bloating
- Change in bowel habit
IBS - epidemiology
- F > M (2:1)
- most commonly affects ages 20 - 30 years
- Prevalence in the general population 10- 20%.
- Significant prevalence of IBS in older people
Possible causes
Causes of IBS unknown: could be
- gut hypersensitivity
- disturbed colonic motility
- post-infective bowel dysfunction (can start after episode of gastroenteritis)
- defective anti-nociceptive system
- Stress commonly aggravates the disorder
Clinical features
- chronic, relapsing, often life-long
- crampy abdo pain/discomfort relieved by defecation or passing wind
- change in bowel habit together with disordered defaecation (constipation or diarrhoea or both)
- sensation of abdominal distension/bloating
- sensation of incomplete evacuation or urgency
- sometimes worse post prandial
- psychological issues eg stress/anxiety
Other complaints
dehydration, lack of sleep, anxiety and lethargy, time off work, avoidance of stressful or social situations and reduction in quality of life.
IBS - differential diagnoses
- IBS
- IBD
- colorectal cancer
- coeliac’s
- ovarian cancer
also consider pregnancy/PID/endometriosis in younger women
Colorectal cancer - red flags
- Rectal bleeding and looser stool and/or increased frequency of ≥ 3 weeks duration (age 40 and over)
- Rectal bleeding without change in bowel habit ≥ 3 weeks duration (age 50 years and over)
- Change of bowel habit (tendency to looser stools) for ≥ 3 weeks without bleeding (age 50 years and over)
- Abdominal mass thought to be large bowel cancer (any age)
- Palpable rectal mass (any age)
- Males of any age with Hb ≤ 11g/100ml; Ferritin ≤30 mg/dL; MCV ≤ 79 (iron deficiency picture)
- Non menstruating female with Hb ≤ 10g/100ml; Ferritin ≤30 mg/dL; MCV ≤ 79 (iron deficiency picture)
Ovarian cancer - red flags
- women > 50 usually
- frequent or persistent bloating
- feeling full, reduced appetite
- pelvic or abdo pain
- increased urgency, frequency of PU.
- > 50 with new onset IBS
- IMB/PMB
IBS - diagnostic criteria
abdominal pain/discomfort relieved by defaecation or a/w altered bowel frequency or stool form.
With at least 2 of 4 symptoms:
1. Altered stool passage (straining, urgency, incomplete evacuation)
2. Abdominal bloating (more common in women than men), distension, tension or hardness
3. Symptoms made worse by eating
4. Passage of mucus.
suspected IBS - first investigations
In people who meet the IBS diagnostic criteria investigate with:
- FBC (normal; anaemia suggests non-IBS disease)
- ESR/CRP (elevated in IBD)
- Antibody testing for coeliac disease: anti endomysial antibodies (EMA) or anti tissue transglutaminase (TTG).
other investigations to consider
- stool studies (if diarrhea) - can exclude presence of parasites, particularly Giardia lamblia
- fecal calprotectin (<40 micrograms/g makes IBD unlikely (and IBS more likely)
- colonoscopy (rule out colorectal cancer)
- serum Ca125 (rule out ovarian cancer)
Treatment - conservative
- Patient education, Self help, Relaxation
- low FODMAP diet
- reduction of stress
what is a low FODMAP diet?
Diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols - eg some fruits, sweeteners, lactose, honey, some veg, legumes
Eating/drinking FODMAPs increases the delivery of readily fermentable substrates and water to the distal small intestine and colon—which results in luminal distention and gas—the reduction of FODMAPs may improve functional GI symptoms.
Treatment - pharmacological
- antispasmodics: hyoscine butylbromide (buscopan), mebeverine
- constipation-predominant: laxatives but avoid lactulose
- diarrhea-predominant: loperamide (imodium)
- consider peppermint oil
- consider antidepressants (TCA- amitryptiline, SSRI- sertraline)
- consider linaclotide if other laxative haven’t helped and they have had constipation for > 12 months
