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What is Crohns

Crohns Disease is a chronic Inflammatory Disorder caused by overreaction of the immune system to gut bacteria. Crohns, along with UC, is an inflammatory bowel condition.

Crohns is associated with granulomatous inflammation (as opposed to UC that does not form granulomas) that can affect any part of the GI tract (Most commonly terminal ileum and colon). It affects all layers of the gut wall (transmural) and the areas affected are not continuous (skip lesions) with a typical Cobblestone appearance. Crohns is a lifelong condition that undergoes periods of periods of flare ups, interspersed with remissions or less active disease.

Patients with Crohns disease are at risk of small bowel obstruction, and abscess formation. Some patients can get a toxic megacolon; however, this is rare and mainly associated with UC. Chronic complications include an increased risk of colorectal cancer, Osteoporosis (from long term steroid use), Fatty Liver disease and Cholangiocarcinoma


What will you find on a history taking of Crohns Disease?

Diarrhoea – May be bloody but not necessarily
Abdominal Pain
Weight Loss
Perianal Disease – Abscess, Fistula
Fistulae - Colo-vaginal, perianal, entercutaneous
Extra intestinal manifestation – Erythema Nodosum, Pyoderma Gangrenosum, Conjunctivitis/Episcleritis/Iritis, Large Joint arthritis, Sacroiliitis, Ankylosing Spondylitis, Fatty Liver, Malnutrition
Systemic - Fatigue, Malaise, Anorexia, Fever

Risk Factors:
Age peaks between 15-40 and 60-80
Uncommon in black or Asian people

Specific Questions to ask:
Need to assess smoking history as this makes Crohns worse
Family History
How is patient dealing with hard disease?
Need to rule out infective cause - Recent travel, antibiotic use, affected friends/family, night sweats etc
Recent antibiotic use/hospital admission - Looking for C. diff

GI questions to ask:
Nausea and vomiting
Weight loss
Abdominal Pain
Change in bowel habit

Ulcerative colitis - No small bowel involvement or perianal disease, more bleeding. Differentiated by biopsy
C. diff infection - Recent hospital stay
Colorectal cancer - Older age and a positive FH
Diverticulitis - Commonly presents with left-sided abdominal pain in patients aged 50 years and older.
IBS - Bloating relieved by defecation
Coeliac Disease – May have very similar presentation, there will not be blood in coeliac disease. Differentiated by Anti TTG blood test and biopsy
Intestinal tuberculosis - Consider in patients from endemic areas who present with suggestive symptoms, such weight loss and night sweats. Look for pulmonary symptoms of TB (Ileocecal biopsy shows caseating granulomata). This is rare but important to exclude
Gastroenteritis - History of sick contacts and travel to endemic areas
Ischaemic Colitis - Most patients have risk factors such as atherosclerotic diseases, pain will be much worse and may be one big bleed
TB spread to GI system
Differential for Perianal Disease – Peri-anal sepsis, Diverticular Disease, Anorectal Cancer


What are the signs of Crohns

End of the bed:
Large Joint Arthritis
Reduced Schober’s Test - Ankylosing Spondylitis
Signs of anaemia or malnutrition
Mouth Ulcers
Eye Problems - Conjunctivitis, Episcleritis, Iritis
Abdominal Tenderness - Generally in the LRQ with a possible abdominal mass
Abscess and abdominal sepsis if peritonitis
Abscess/Fistulae/Skin Tags
Digital rectal examination for occult blood and exclusion of a mass should be performed
Erythema Nodosum
Pyoderma Gangrenosum
During Flare ups:


What are the investigations used for Crohns and what will they show?

Stool cultures (send multiple samples)– A negative stool culture is required for diagnosis, also helps to rule out infective causes.
Test stool sample for C. diff
Full set of observations

FBC – Looking for an underlying infection or Anaemia due to chronic disease/malnutrition
ESR/CRP - Correlate with disease activity
U&E – Looking for any signs of Dehydration (or secondary AKI), Diarrhoea may cause low electrolyte levels, specifically hypokalaemia
LFT - Looking for any underlying disease and hypalbuminaemia from malabsorption
Total Iron Binding Capacity/Ferritin - Iron deficiency associated with GI bleeding or malabsorption of iron.
B12/Folate - Malnutrition

Abdominal X-ray - To look for colonic/small bowel dilation, may show sacroiliitis or intra-abdominal abscess
CT Scan - Skip lesions, bowel wall thickening, surrounding inflammation, abscess, fistulae
Ileocolonoscopy with biopsies - Biopsy of terminal ileum (most commonly affected site) and all other affected sites
Upper GI endoscopy with biopsies – In patients with upper GI symptoms
Pelvic MRI – In patients with Perianal Disease (Not required in simple fistulae)
Capsule Endoscopy or MRI to assess small bowel and rest of GI tract if affected, including fistulae, pelvic disease or strictures

Special Tests:
Faecal Calprotectin – Used to differentiate IBS and IBD. Faecal calprotectin will only be raised in IBD


What is treatment of Crohns Flare Ups

A-E approach
Get IV Access/Give O2 to maintain sats of 94+ /Attach 12 lead ECG
Assessment with AMPLE history and brief examination
Get help - Medical reg on call
Frequent Observations - Constant or 15 minutely
Daily Abdominal X-ray and examination looking for complications such as perforation or peritoneal abscess formation

Mild (Symptomatic with no Systemic Signs):
Oral Steroids - Prednisolone for 1 week then taper down for next 7 weeks

Severe (Systemic Signs, Fever, Weight Loss, >4 stool per day or severe abdominal pain):
Admit Patient and give IV fluids and electrolyte replacement as indicated
IV steroids - Hydrocortisone (Once improving consider changing to Oral Prednisolone)
If the patient has had >2 flare ups in the last year, consider adding azathioprine or mercaptopurine to the steroids to induce remission.
If not improving after that try Methotrexate or Biologics (E.g. Anti TNF)
Can use an elemental diet to induce remission
VTE prophylaxis (IBD patients are at increased risk of VTE – Unknown cause)

Perianal Disease:
MRI and Examination under anaesthesia
Fistula - Fistulotomy and excision. High fistulas are closed with a “Seton Suture” and low sutures are left to heal by secondary intention
Abscess - Incisions and drainage under anaesthetic


What is the treatment for Crohns Maintenance

Quit Smoking
Optimise Nutrition and BMI
1-5 yearly colonoscopy surveillance for colorectal cancer
Educate patients on when to present to hospital - unintended weight loss, abdominal pain, diarrhoea, general ill health

Azathioprine or Mercaptopurine – Used to maintain remission, generally offered if >2 flare ups per year but this is a joint decision and need to weigh up side effects vs risk of flare ups.
Methotrexate 2nd Line - If the above do not work or if methotrexate was needed to induce remission

Inform the patient this will be non-curative
Indications – Disease limited to the Distal Ileum, Complications that require surgery e.g. Abscess, Obstruction, Strictures
Most patients will require a surgery eventually