Functional Bowel Disorders Classification and Diagnostic Criteria Epidemiology Pathophysiology Role of psychosocial factors. Diagnosis Treatment recommendations When or if to refer.
Definitions No objective biological markers exist. Spectrum of FGD defined by symptoms in the absence of structural pathology. Manning Criteria Rome I and II
Manning criteria Pain relieved by defaecation Looser stools with pain More frequent stools with pain Abdominal distension Passage of mucus Sensation of incomplete evacuation
Rome II criteria At least 12 weeks or more in preceding 12months of abdominal discomfort or pain with 2 of the following Relieved by defaecation Onset associated with change in frequency of stool Onset associated with change in consistency of stool. Supportive features
Altered stool frequency Altered stool form Altered stool passage (straining, urgency, incomplete evacuation) Passage of mucus Bloating
Prevalence of IBS as judged by Manning Criteria No of symptoms 123456 Male2710.75.02.31.30.9 Female46.82418.104.22.168
Epidemiology Prevalence 14-24% women, 5-19% men Any age but decrease after 60 15% seek medical attention 25-50% of all referrals to gastroenterologists 2 nd highest cause of work absenteeism Direct cost in USA $1.7billion in 2000
Social Impact Social activities restricted Fear of travel Work absenteeism (14.8 days per year v 8.7) Anxiety Extreme lethargy In extreme virtually housebound. Unnecessary surgery
Gastrointestinal motility Basal motility is not consistently altered in IBS patients Gastro-colonic response in IBS results in increased duration of rectosigmoid contractions, compared with controls. Stress and anger increase colonic motility in IBS. In general motility studies are inconsistent and the normal range is wide.
Visceral Hypersensitivity Patients with bloating do not have increased quantities of gas in GI tract. Many have lowered tolerance of balloon distension in rectum (and elsewhere). Repetitive stimulation of the sigmoid can induce visceral hyperalgesia in IBS patient but not in controls. Stress and meals increase sigmoid contractions and hence may induce transient hyperalgesia in IBS.
Visceral Hypersensitivity BUT no increased visceral hypersensitivity is found in IBS non-presenters Visceral hypersensitivity is also found in patients with other chronic pain syndromes. Recent work involving functional MRI suggests that visceral hypersensitivity probably results from altered CNS processing of sensory information.
Psychosocial Factors IBS patients referred to hospital have an increased prevalence of anxiety, depression, phobias and somatisation. 25% think they have cancer. Increased history of abuse in this group (20- 30%). Non-presenters have same prevalence of these as controls. Psychological distress thus appears to influence experience of IBS rather than cause it.
Stress Acute stress mimicked by CRF infusion Increased colon motility Decreased upper gut motility Induces abdominal pain Chronic stress >50% link onset to stressful life-event In one study 60% of patients without chronic stressor improved compared with 0% with.
Postinfectious IBS found in 20-30% after acute bacterial infection RR of IBS after proven infection =14 (nested case-control of 318 pts with bacterial gastroenteritis and 584,308 controls) Risk increased if long duration initial attack, female, younger age.
Postsurgical Hysterectomy, cholecystectomy, appendicectomy and any other abdomino- pelvic surgery may precipitate IBS. Prospective studies show about 10% develop new bowel symptoms within 6 months, usually constipation predominant IBS.
Mechanisms include Altered bowel flora after antibiotics, Neural damage with subsequent aberrant regeneration. Bile salt diarrhoea. Misdiagnosis of original problem.
Diet Intolerance 30-60% have specific intolerance Wheat, dairy, potato, corn, coffee, onions, beef, oats, white wine Allergy Much less common Asthma, urticaria, angioedema RAST or pinprick
Diagnosis in General Practice Careful detailed history over time Examination including rectal examination where relevant. If typical features,
Further tests Colonoscopy if>45y or FH Barium enema Barium follow through Ultrasound rarely helpful
Treatment of IBS General principles Therapeutic relationship Patient education Dietary modification Psychological approaches Simple drugs Complicated drugs
General Principles No known cure but benign disease Focus on symptom relief Alleviate concerns Simple explanation Consider hidden agenda Identify exacerbating factors Identify psychiatric comorbidity
Dietary Modification Fibre Lactose avoidance Avoidance of foods that increase flatulence Beans, onions, carrots, sprouts, prunes etc Modified exclusion diet ( eg as per Hunter), >50% remission in 2 studies.
Modified Exclusion Diet Meat Fish Fruit (not citrus) Vegetables (not sweetcorn, onion, potato) Rice
Simple Drugs symptom based Antispasmodics Antimuscarinics- dicyclomine, hyoscine Others- alverine, mebeverine, peppermint Meta-analysis of 23 controlled trials found a small but significant benefit (53 v 41%) Mebeverine failed to show improvement in pain but did result in global improvement. Dicyclomine was best for pain.