Inflammatory Bowel Disease – diagnosis

• Crohn’s Disease and Ulcerative Colitis have an increasing incidence and markedly higher prevalence in the western world
• Treatment has moved to be more aggressive early on, as going gentle can make the disease worse
• The majority of patients are managed in the community, but acute admissions are common
• See sections on Ulcerative Colitis and Crohn’s Disease for a more detailed review of management

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Clinical assessment of suspected IBD (first presentation)

• Timing
  • • 20% of patients with IBD have symptoms for > 5 years before diagnosis made (therefore a long duration of symptoms does not rule it out)
    • Symptoms for > 6 weeks is more suggestive of IBD than infection (but doesn’t rule it out either)
• Symptoms
  • • Bloody diarrhoea and mucus (watery diarrhoea with no blood a bit more suggestive of infection, but could be either)
    • Faecal incontinence/urgency
    • Abdominal pain/cramping
    • Weight loss
    • Systemic symptoms/fevers
    • Nocturnal symptoms (often not present in IBS, which is a differential, although IBS can co-exist)
    • Perianal symptoms
    • Vomiting
    • Extraintestinal manifestations – joint involvement / arthralgia (24%), ocular (27%), skin (35%)
• Ask about
  • • Travel history – infectious causes
    • Sexual history – proctitis and enteric infections can be sexually transmitted
    • Unwell contacts
    • Unusual / undercooked food
    • Family history
    • Extraintestinal manifestations – swollen joints, sore eyes, rashes, mouth ulcers, jaundice
    • Previous radiotherapy
    • TB risk (mimic)
    • Drug history – especially antibiotics, NSAIDS, laxatives
    • CV risk – ischaemic gut in the differential
• Clinical exam
  • • Document nutritional status / weight as part of GI exam
    • Gastrointestinal exam – check for tenderness, masses, fever, clubbing
    • Check for extra-intestinal manifestations
      • • Skin – Erythema Nodosa (associated with flairs), pyoderma gangrenosum, sweets syndrome
        • Joints – arthritis, tendonitis, ankylosing spondylitis, sacroiliitis
          • • Type 1 arthropathy < 5 joints, self-limiting, associated other extraintestinal manifestations, alongside bowel inflammation
            • Type 2 arthropathy > 5 joints, prolonged and independent course, associated with uveitis only
        • Eyes – uveitis, episcleritis, iritis
        • Oral ulcers, stomatitis
        • Primary Sclerosing cholangitis (significantly increases risk of cancer), pancreatitis, autoimmune hepatitis, gallstones
        • Other – pleuritis, myocarditis, renal stones
• If IBD suspected but not formally diagnosed – usually best to hold off steroids and discuss with gastroenterology

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Biochemistry and cultures

• Bloods
  • • TSH, Coeliac screen, CRP (needed for scoring), LFTs, haematinics and vitamin levels, amylase or lipase, group and save, amoebic serology if relevant history
    • A very high CRP and platelets steers towards infection, but could be either IBD or infection, and could be both
• Multiple stool samples required
  • • Standard microscopy and culture
    • C Diff
    • Viral PCR
    • Cysts, ova and parasites if relevant travel – treating amoebic dysentery with steroids can be disastrous
• Faecal calprotectin
  • • Helps to differentiate IBS from any inflammation in the bowel, including IBD and cancer
    • Might also ensure some patients are seen more urgently by gastroenterology
    • Best performed in the community, less of a role as inpatient (if patient unwell enough to come to A&E, then calprotectin likely elevated whatever the cause)
    • The result won’t be back during the acute take but often worth sending if a patient is going home
    • If the patient is aged > 45 years, with change in bowel habit – they probably still need a scope (and maybe on a 2 week wait pathway) regardless of the calprotectin, to rule out cancer
    • Useful to monitor response to treatment
    • Interpretation
      • • If > 1000 μg/g extremely likely to be IBD
        • If >250 μg/g suspicious for IBD especially if bloods abnormal too. Refer urgently to gastro
        • If < 50 μg/g highly unlikely IBD (93% sensitivity and specificity), and still unlikely to be IBD if in 50-100 range. However, do not let a low level override clinical suspicion
        • If 50-250 μg/g – consider repeat testing or non-urgent referral. Could be IBD or infection
    • Sensitivity increases the more distal the pathology is
    • False negatives – it can’t reliably rule out small bowel Crohn’s
    • False positives occur with
      • • NSAIDs in last 6 weeks (avoid checking in this instance)
        • PPI use
        • Bacterial GI infection
        • Coeliac
        • Colorectal cancer
        • Other medical conditions – pancreatitis, HIV, appendicitis, diverticulitis, ankylosing spondylitis, ETOH use, GORD

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Endoscopy and imaging

• AxR sometimes indicated (see ulcerative colitis for specific indications and radiological features)
• CT scan
  • • Colitis or enteritis is not always IBD. Infections like yersinia and salmonella can cause right sided colitis too
    • CT scan doesn’t help differentiate IBD from infection however
    • Ischemic colitis always needs considering
• Scopes
  • • Bloody diarrhoea needs an urgent flexi sigmoidoscopy (with enema preparation if no dilatation on AxR). Not requested often enough
    • A flexi sigmoidoscopy only helps distinguish UC from non-UC if you have a continuous pattern (which is also seen in infections)
    • After the acute illness, patients may need a full ileocolonoscopy to delineate disease extent / severity and to exclude Crohn’s
    • Scopes can also help diagnose CMV colitis
    • An OGD is indicated if there are upper GI symptoms in young patients with suspected Crohn’s
    • Sometimes biopsies are not diagnostic
    • Colonic surveillance begins at 8 years post diagnosis
• MRI small bowel
  • • Consider MR small bowel if scope non-diagnostic
    • Always do MR small bowel if Crohn’s suspected

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Important differentials

• Careful not to misdiagnose something else as IBD (it’s a lifelong diagnosis)
• Consider
  • • Infection including C Diff (also CMV, giardia, yersinia, amoebic dysentery and others)
    • TB
    • Microscopic colitis
    • Ischaemic gut – especially if lots of pain and CV risk
    • Diverticulitis
    • Malignancy
    • IBS (including post-infectious IBS)
    • Chronic pancreatitis

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Complications

• Cancer – colonic (do surveillance colonoscopies), intestinal lymphomas, small bowel adenocarcinomas, cholangiocarcinoma (especially if co-existing PSC), skin cancers due to biologics
• Toxic megacolon (>5.5cm dilatation on AxR)
• Post-surgical complications eg pouchitis
• GI bleed
• Nutritional deficiencies – malabsorption, severe anaemia, vitamin B12 deficiency, electrolyte derangement
• VTE
  • • VTE prophylaxis is vital for all patients
    • 3-fold increase of VTE during flair compared with other hospitalised patients
    • 27 x increased risk compared with controls
    • Anticoagulation or antiplatelets are usually safe even if rectal bleeding as major bleeds are unlikely
• Extra-intestinal manifestations – see above
• Treatment side effects including infection from immunosuppression
• C Diff – not always associated with antibiotics, also associated with steroid use
• In Crohn’s – Abscesses (perianal or intestinal), perforation, obstruction, strictures, fistulas