BMJ learning/bpac

• Diarrhoea predominant IBS far most common cause of abdo pain and diarrhoea

  • 20-40yo

• 10% UK population

• usually well between episodes

Pathophysiology

• remains unclear

• complex biopsychoscoial illness

  • psychological

    • stress

    • emotional state

  • social

    • upbringing

    • support

  • biological factosr

    • gut motility

    • viscueral sensitivity

Key symptoms

Altered gastrointestinal motility

• luminal contractions that are increased in frequency and irregularity

• shorter or prolonged transit time

• exaggerated motor response to ingestion of food

Altered sensation within GI tract

• increased sensations from GI tract in response to stimuli

• Visceral hypersensitivity

  • selective hypersensitisation

Psychosocial

• increase frequency and severity of symptoms

Diagnosis

• positive diagnosis

• presence of symptoms

• any;

  • >6mo

  • Abdominal pain or discomfort

    • varies widely

    • often made worse when eating

    • premenstrual

    • relief of pain or discomfort when defaecating characteristic of IBS

  • Bloating

    • more likely to be described by females compared to males

  • Change in bowel habit

    • most consistent symptoms

      • stool consistency

      • frequncy

      • urgency

        • after eating specific trigger foods

      • straining

      • incomplete evaculation

      • faecal incontinence

    • mucous

• more common in people with family history

• other cormorbitieis

• gastroenteritis can be a ppt. event

consider:

• coeliac disease

• IBD

• lactose intolerance

• colorectal cancer

• Small - intestinal bacterial overgrowth, microscopic colitis, diverticulitis, GI condtions

• Gynaecological conditions

  • endometriosis

  • PID

  • ovarian cancer

Rome 3 criteria

• recurrent abdominal pain or discomfort for 3d in last 3 mo associated with ≥2:

• improved with defecation

• onset associated with change in frequence of stool

• onset with a change in form, appearance of stool,

• in absence of strutural or metabolic abnormalities

Red flags

• Weight loss

• Nocturnal symptoms

• rectal bleeding not due to heamorrhoids

• FHx of colon cancer

• abnormal physical exam

• onset >50yo

• iron def. anaemia

• raised inflammatory markers

investigations

• suggest:

  • FBC

  • CRP

  • coeliac antibodies

  • consider ferritin, lft renal function, tsh

• faecol calprotectin

  • not usually indicated

  • in uncertainty

    • negative result exclusdes IBD

• yield from further investigations small but occ. of value

• 2% stool sample abnormal

• 2% colonoscopies occult IBD

• TSH abnormal in 6% ( no different than general population)

• lactose malabsorption 23% (no differnet from gen pop)

Sub types

IBS -D

• most common subgroup

IBS - C

• females > males

• prolonged colonic transit time

IBS - M

• mixed picture

treatment

• Dietry modifications in vast majority wil be effective

• British dietetic association - 3 tiered approach

  • 1. first line

       1. heathy and nutritionally adequate diet

          1. regular meals

          2. good eating behaviour: chewing food, taking time, not eating late at night

          3. regular adequate fluid intake: avoiding carbonated bev, caffeine and etoh

          4. common aggravating food

             1. caffeine

             2. eoth

             3. fatty food

             4. spicy food

             5. wheat

             6. cheese

             7. milk

             8. pure fruit juice

             9. artifical sweetner

             10. vege that increase flatus

          5. IBS - D may need to reduce fibre

    2. second line

       1. constipation:

          1. increase soluble fibre

             1. oats, psyllium husk

       2. consider low FODMAP diet

          1. refer dietician

       3. 4 week trial of probiotics

          1. may worsen in some patients

    3. 3rd line

       1. exclusion diet

• treatment should address most troublesome symptoms

  • consider TCA - target >1 symptom

Diarrhoea:

• reduce fibre

• Loperamide 2mg with each loose stool - up to 60mg/day

  • RCT relieve urgency and passage of stool in patients with diarrheoa predominant ibs

  • for urgency can take 2-4mg 20min proir to leaving house

• antispasmodiic

  • mebeverine

    • 135mg tds prn 20min prior to meals

• ondansetron (5HT3-receptor antagonist)

  • modulate effect of stressors on gut function

constipation

• increase soluble dietary fibre

• abouid eating FODMAPS

• laxatives may be required

  • stimulants avoided

  • macrogol = osmotic laxative

  • 1 sachet once daily dissolved in half a glass - increase to 2-3 sachets daily

Pain

• antispasmodics

  • mebeverine

• avoid narcotics

• domperidone

• TCA efective in reducing pain, also diarrhoea

FODMAPS;

Fermentable, Oligo-saccharides, Disaccharides, Mono-saccharides And Polyols

Fructose in fruidts

Fructans wheat, rye, onions

Artificial sweeteners

further information; monash