IRRITABLE BOWEL SYNDROME IBS

RAHNA66

DEFINITION EPIDEMOLOGY ETIOPATHOGENESIS CLINICAL FEATURES DIAGNOSIS RED FLAG SIGNS INVESTIGATIONS TREATMENT

DEFINITION It is a functional bowel disorder characterized by abdominal pain or discomfort and altered bowel movements in the absence of detectable structural abnormalities

Chronic, recurrent ,relapsing and often lifelongOften overlap with other functional disorders like fibromyalgia, headache, backache and genitourinary symptoms

EPIDEMIOLOGY Prevalence : 1-20% worldwide (10% to 20% - US and Europe 5% - Asian countries) Incidence : 1-2% per year 2-3 times more common in women Most patients have their first symptoms before 45 years of ageINDIA Prevalence is 4-8% More common in men

ETIOPATHOGENESIS Etiology is uncertain and maybe multifactorial

Pathogenesis in IBS is poorly understoodGI Motor AbnormalitiesVisceral HypersensitivityBrain gut axis DysregulationAbnormal Psychological features

Postinfectious IBSRisk factors- young females,prololged duration of initial illness, toxicity of infecting bacterial strain

Microbes involved in initial infection – Campylobacter ,salmonella and shigella

Immune activation and low grade mucosal inflammationAltered gut floraAbnormal serotonin pathways

Serotonin plays an important role in regulation of GI motility and visceral perception

IBS –D patients show increased 5HT containing enterochromaffin cells in colon

CLINICAL FEATURES• Abdominal pain

and discomfort• Altered bowel

habits• Gas and

flatulence• Upper GI

symptoms

Abdominal pain or discomfort A prerequisite for the diagnosis of IBS It is episodic and crampy & highly variable in intensity and location

Sleep deprivation and malnutrition is uncommon Pain exacerbated by eating and emotional stress and improved by passing stools or flatus

In females symptoms worsen during premenstrual and menstrual phases

Altered bowel habits- Alteration in bowel habits most consistent clinical feature Most common pattern is constipation alternating with diarrhea At first constipation is episodic but later becomes continuous and unresponsive to laxatives

Stools are usually hard with narrowed caliber Sense of incomplete evacuation Pts. with diarrhea have a stool volume <200ml and maybe associated with passage of mucus but not blood

Nocturnal diarrhea not seen

Gas and flatulence- Pts complain of abdominal distention and increased belching or flatulence

Upper GI symptoms- 25-50% complain of dyspepsia, heartburn, nausea and vomiting

Indian patients have more of upper GI symptoms

TYPES IBS-D (Diarrhoea predominant) IBS-C (Constipation predominant) IBS-M (Mixed diarrhoea and constipation)

Usefulness of subtypes debatable Within 1 yr 75% change subtypes & 29% switch between IBS-C and IBS-D

DIAGNOSIS No clear diagnostic markers exist for IBS

So diagnosis depends on positive clinical features and ruling out organic diseases by careful clinical examination and investigations

Diagnosis can be made confidently in most patients using Rome III criteria + absence of red flag signs + supportive symptomswhich include defecation straining, urgency or a feeling of incomplete bowel movement ,passing mucus and bloating

Sensitivity 17% Specificity 95%

RED FLAG SIGNS & SYMPTOMS Unintentional and unexplained wt. loss Rectal bleeding Family h/o bowel/ovarian cancer A change in bowel habit to loose and/or more frequent stools persisting for

more than 6 wks in a person aged over 60yrs. Anemia Abdominal masses Rectal masses Inflammatory markers for IBD

INVESTIGATIONSTo rule out organic causes CBC ESR CRP Stool examination for ova and parasites Antibodies for Coeliac Disease Hydrogen breath test Sigmoidoscopy when more than 50 years/ red flag signs present Younger individual with mild symptoms – minimal diagnostic evaluation, Older – undergo more thorough evaluations

DIFFERENTIAL DIAGNOSIS IBD COLORECTAL CANCER COLONIC TB FRUCTOS/LACTOSE INTOLERENCE’ CELIAC SPRUE Endocrinopathies- HYPOTHYROIDISM ,HYPERTHYROIDUSM INFECTIOUS COLITIS ACUTE INTERMITTENT PORPHYRIA and LEAD POISONING PHYCOLOGICAL –ANXIETY,DEPRESSION

TREATMENT Patient education and counselling Dietary alteration Pharmacotherapy Psychotherapy

PATIENT COUNSELLING Reassuring the patient is the most successful form of treatment for IBS

Many are concerned that they have developed cancer – more anxiety -more colonic symptoms

Explain functional nature of disorder and how to avoid obvious food precipitants

Emphasise on expected chronicity of symptoms with periodic exacerbations

DIET MODIFICATION Eliminate food stuffs that appear to produce symptoms Consume high fibre diet – IBS-C Exclude wheat ,diary and gluten –Pain and bloating Avoid legumes and excess dietary fibre - IBS-D Diet low in FODMAPs(Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) FODMAPs areshort chain carbs poorly absorbed in small intestine and fermented by bacteria in colon to produce gas

DRUGS

Antidiarrheal agents Delay faecal transit , increase colonic segmentaion contractions and reduce

rectal perceptionSerotonin receptor agonist and antagonist

5 HT3 receptor agonist –5 HT release increases secretions and reduces GI transit time and cause constipation and hence useful in IBS-D. Eg:- Alosetron

s/e-Causes ischemic colitis and severe constipation

5 HT4 agonist – are prokinetic eg Tegaserod- Suspended due to CVS events.

Stool bulking agents Fibre speeds up colonic transit and prevent excessive hydration and

dehydration of stool Chloride channel activators

Chloride secretion induce passive movement of Na and water into bowel lumen and improve bowel function

Guanylate Cyclase-C Agonist Activation of GC-C generates cGMP which triggers secretion of fluid, sodium

and bicarbonate

Antidepressant drugs TCAs reduce visceral hypersensitivity Their antimuscarinic effects cause constipation. Useful in IBS-D SSRIs are secretagogues and stimulate GI motility. Helpful in IBS-C

Modulation of gut flora- Rifamixin , probioticsAntispasmodics

provide temporary relief for painful cramps related to intestinal spasm Inhibit gastrocolic reflux and reduce postprandial pain s/e –xerostomia, urinary retention ,blurred vision ,drowsiness

PSYCHOLOGICAL THERAPY Psychological therapy is effective in two thirds of patients with IBS who do

not respond to standard medical treatment Cognitive behavioral therapy Hypnotherapy Dynamic therapy

TO CONCLUDE  Chronic relapsing condition with considerable financial burden and impacts overall quality of life

At present only symptomatic therapy available Drugs don’t alter the clinical course Treatment should be tailored to the individual patient and should be a combination of therapies

No serious complications Haemorrhoids - aggravated by constipation and diarrhoea Vitamin and mineral deficiencies – because of avoiding certain foods

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