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ulcerative_colitis

ulcerative colitis

introduction

epidemiology

  • annual incidence in USA 1 case per 1000 white adults and rising
  • affects all age groups, esp. 3rd & 4th decades of life
  • almost exclusive to industrialised nations with urban > rural
  • FH UC in 10-15%
  • whites 4x risk cf non-whites
  • M=F although increased risk if on OCP
  • outside the tropics, it is the commonest cause of prolonged bloody diarrhoea

pathology

  • inflammatory reaction of the mucosa of the colon:
    • always arises 1st in the rectum
    • rectum is only part involved in 10-38% cases
    • pancolitis occurs in 10% cases
    • uniformly continuous disease process with no skip lesions
  • mucosal appearance:
    • thick inflammatory exudate of pus, blood, mucus covering irregular shallow ulcers interspersed with islands of swollen mucosa (“pseudopolyps”)
    • increased mucosal friability
    • microscopic “crypt abscesses”
  • chronic disease results in colon becoming rigid, foreshortened tube lacking haustral markings

associations:

  • sacroiliitis, ankylosing spondylitis, cholangitis, hepatitis, hepatitis, amyloid
  • colonic Ca

clinical features

initial presentation:

  • chronic insidious recurrent abdominal pain, anorexia, weight loss, mild diarrhoea
  • acute onset of bloody diarrhoea, abdo. pain, +/- tenesmus, vomiting & fever

recurrences:

  • often associated with:
    • emotional stress, infections, other acute illnesses
    • pregnancy, dietary indiscretions, use of cathartics or antibiotics
    • withdrawal of anti-inflammatory or steroid Rx
  • extraGIT manifestations may be present in up to 20% cases:
    • peripheral arthritis, apthous ulcers, erythema nodosum, pyoderma gangrenosum

complications:

fulminant colitis

  • occurs in 10-15% pts
  • parameters suggestive of this:
    • > 6-8 stools per day
    • anaemia - H'crit < 30% (may not be evident until after rehydration)
    • T > 38deg C
    • LOW > 10% of premorbid weight
    • tachycardia
    • se albumin < 30g/L
    • failure of usually effective Rx regimes
    • failure of 5-7 day course of intensive outpatient Rx

toxic megacolon

  • a manifestation of fulminant disease which usually occurs during initial acute episode
  • mainly involves transverse colon causing:
    • septic, apathetic, lethargic looking pt
    • high fever, chills, tachycardia
    • progressive abdoinal pain, tenderness & distension
  • 25% result in perforation
  • precipitants may include:
    • use of anti-diarrhoeal agents
    • vigorous use of cathartics/enemas or barium enema

perforation

  • 50% occur in pts with fulminant disease without toxic megacolon
  • 50% occur in pts with toxic megacolon

large bowel obstruction due to stricture formation

  • 10% pts

massive GI haemorrhage (<1% pts)

  • <1% of patients

perirectal abscess / anal fistula

  • 15% pts
  • tend to occur in 1st year of disease & correlate with severity

colon carcinoma:

  • risk related to severity & duration of disease esp. over last 10-15 years
  • risk appears to be 1% per person per year if have pancolitis
  • overall risk 11% after 26yrs

diagnosis of UC:

confirmed by:

  • if acute, non-fulminating disease:
    • colonoscopy (C/I in fulminating disease as risk of perforation) & evaluation of biopsies
  • chronic disease:
    • barium enema no longer Ix of choice (C/I in fulminating disease as may cause toxic megacolon or perforation if toxic megacolon is present) but may show:
      • rigid, shortened colon with loss of haustrations & destruction of mucosal pattern ⇒ “hoselike” colon
  • if acute, fulminating disease:
    • gentle sigmoidoscopy may be diagnostic as rectum always involved in UC but is indistinguishable from infectious causes
    • plain AXR & erect CXR to exclude:
      • toxic megacolon:
        • transverse colon dilated > 6cm (usually > 8cm)
        • islands of necrotic tissue or gas in the bowel wall may be seen
      • perforation:
        • free gas under diaphragm

differential diagnosis of UC:

  • infectious colitis - Campylobacter, Shigella, enterohaemorrhagic E. coli, C. difficile (colitis_pseudomembranous)
  • acute ameobiasis - can be difficult to detect in stool, so do serology too
  • Crohn's disease - 20% of cases cannot de distinguished histologically or clinically from Crohn's
  • in AIDS pts:
    • chronic diarrhoea & diffuse colonic involvement of Kaposi's sarcoma
  • in elderly pts in particular:

management of UC:

  • admit any new patient suspected of acute UC for Ix and initial control of disease if confirmed:
  • Ix:
    • gentle sigmoidoscopy
    • U&E, FBE, ESR, stool m/c/s ('hot' stool for amoebiasis), serology for amoebiasis
    • AXR, erect CXR
  • Mx in ED:
    • inform surgeons/gastro. unit
    • if severe disease then 5 day regime:
      • nil orally
      • IV maintenance fluids
      • twice daily physical examination - inform surgeons of progress
      • record stool frequency & character as well as TPR,BP
      • daily: FBE, U&E, plain XRs, abdo. girth
      • IV hydrocortisone 100mg 6h (reduce dose after a week according to response)
      • hydrocortisone acetate foam enema 125mg x ii/day (reduce after a week prn)
      • IM vitamins
      • consider need for TPN
    • AVOID anti-diarrhoeals (may cause toxic megacolon)
  • indications for proctocolectomy & ileostomy (total surgical mortality 2-7%):
    • deteriorating colitis after 5 days
    • toxic megacolon
    • perforation
  • less severely ill:
    • steroids po / PR
  • maintaining remission:
    • 5-amino-salicylic acid Rx either:
      • sulphasalazine 1g bd po reduces relapse rate by 65%
        • SE: rash, infertility
      • mesalazine 400-800mg tds po is s effective as sulphasalazine but without the sulphonamide side effects

steroids prn

  • azathioprine for 6months may reduce need for steroids
    • monitor FBE
  • carcinoma surveillance:
  • 1-2yrly colonoscopy (more frequent if high grade dysplasia)
  • if known UC with mild exacerbations or isolated proctitis then can be Mx as outpatients

prognosis of UC:

  • poor if early severe illness or extensive disease
ulcerative_colitis.txt · Last modified: 2009/09/10 20:33 (external edit)