i.e. in exam question land- a young woman, who is probably a lawyer, is stressed at work and comes to the GP complaining of diarrhoea.
Irritable Bowel Syndrome (IBS)
Definition: a chronic mixed group of abdominal symptoms for which no organic cause can be found.
Several diagnostic criteria exist that evaluate symptoms and their duration e.g. Manning, Rome.
Aetiology/ risk factors:
-Visceral sensory abnormalities, gut motility abnormalities, psychosocial factors (particularly stress), food intolerance (e.g. lactose) are all implicated
-Stress or depression is seen in ≥ 50%
Epidemiology: Prevalence = 10-20%
Age at onset ≲ 40 years
> 2x more common in females
–Abdominal pain/ discomfort (often colicky, in lower abdomen)
-that may be relieved by defecation OR
-that may be associated with altered stool form or bowel frequency
–Constipation and diarrhoea may alternate
And 2+ of
–Worsening of symptoms after food
-Other: Nausea, bladder symptoms, backache
–Symptoms are chronic (>6M) and exacerbated by stress, menstruation, or gastroenteritis (post-infection IBS)
⇒Screen for red flag features, which would prompt referral to exclude colon cancer: weight loss, anaemia, PR bleeding, late onset (> 60).
-Examination often normal
-General abdominal tenderness common
⇒Things that would point towards alternative diagnosis: > 40 years old (esp Male), < 6M history, anorexia, weight loss, waking up at night with pain/diarrhoea, mouth ulcers, abnormal CRP, ESR, Hb, coeliac serology.
No specific investigations for IBS but need to do relevant investigations to rule out other differential causes of symptoms, such as UC, Crohn’s, infectious colitis, coeliac disease:
-Bloods- FBC (anaemia?), ESR, CRP, LFTs, Coeliac Serology are enough if the history is classic.
–Colonoscopy (will be normal if IBS):
-If ≳ 50yrs or any marker of organic disease e.g. fever, PR bleed, weight loss
-If family history of ovarian (serum marker CA-125 to help exclude) or bowel cancer have lower threshold
-If diarrhoea prominent:
–Stool culture (for parasites, cysts and infection)
–Anti-endomysial antibodies (coeliac disease)
-Consider barium follow-through (if symptoms suggest small bowel disease) +/- rectal biopsy
-Further investigations, guided by symptoms:
–Upper GI endoscopy (reflux, dyspepsia)
–Small bowel radiology (Crohn’s)
–Duodenal biopsy (Coeliac disease)
–Giardia tests (parasite that often triggers IBS)
-Changing symptoms in ‘known IBS’
-Rectal mucosal prolapse ⇒⇒surgeon
-Food intolerance ⇒⇒ dietician
-Stress or depression or refractory symptoms ⇒⇒ hypnotherapist or psychotherapist
-Cyclical pain, dyspareunia, dysmenorrhoea, raised Ca-125, endometriosis often mimics IBS ⇒⇒ gynaecologist
-Co-existing atopy- IBS 3x more common in atopy ⇒⇒ dermatologist
-Chronic pain overlap syndromes (fibromyalgia + chronic fatigue + chronic pelvic pain) or detrusor problems ⇒⇒Pain clinic
-Ensure a healthy diet. Fibre, lactose, fructose, wheat, starch, caffeine, sorbitol, alcohol and fizzy drinks may worsen symptoms. Probiotics and water-soluble fibre may be ok.
–FODMAP = “Fermentable, Oligo-, Di- (lactose), Mono-saccharides (fructose) And Polyols (sorbitol). FODMAP restriction has been found to improve symptom control in people with IBS.
Depending on predominating symptoms
–Constipation Bisacodyl and sodium picosulfate can help.
Ispaghula has non-fermentable water-soluble fibre (better than lactulose which ferments, exacerbating bloating)
Increasing fibre is not a good solution as it can worsen flatulence/bloating, so insoluble fibre should be avoided.
–Diarrhoea Avoid sorbitol sweeteners
Bulking agent +/- loperamide (2mg after each loose stool, max 16mg/d)
–Colic/bloating Oral antispasmodics: mebeverine, alverine citrate, dicycloverine
Adding Simeticone improves spasm (anti-foaming agent)
Probiotic strains: Bacillus coagulans GBI-30, B.infantis 35624, E.coli DSM17252, L.acidophilus
Cognitive behavioural therapy (CBT)
Tricyclics e.g. amitriptyline
-physical and psychological morbidity
-increased incidence of colonic diverticulosis
Prognosis: in 50% symptoms go or improve after 1 year. Less than 5% worsen.