IBD- Crohn's Disease Flashcards
What is Crohn’s Disease?
Crohn’s disease is a chronic inflammatory disorder, which can affect any part of the gastrointestinal tract from mouth to anus.
What is the cause of CD?
CD is thought to result from an abnormal immunological response to one or more aetiological factors within a genetically susceptible individual.
What are the risk factors of CD?
Genetics:
- polygenic disease
Immune system:
Some research suggests that there may be an abnormal immunological response to normal intestinal microflora. Typically, a Th1 helper cell predominant response is seen leading to increased levels of pro-inflammatory cytokines (e.g. TNF-alpha)
Environmental:
- Smoking increases the risk of Crohn’s, while it appears to be protective UC. Western diets, antibiotics and contraceptive use are also implicated.
What is the percentage distribution of CD patients in terms of where Crohn’s affects them in their bodies?
- 80% patients have evidence of small bowel disease which occurs mostly in the distal ileum (terminal ileitis)
- 50%- small bowel and colonic disease
- 33% have small bowel disease only
- 20% have colonic disease only (making it harder to distinguish between UC and CD)
- 33% patients suffer from perianal CD, which includes a variety of conditions that affect the perianal area (skin tags, fissures, fistulae, abscesses, anal canal stenosis)
What are the macroscopic and microscopic changes seen in CD?
Macroscopic:
- cobblestone appearance, caused by small superficial ulcers which become deep and serpiginous
- bowel wall thickening, lumen narrowing, deep ulcers, fistulae and fissures
Microscopic:
- lymphoid hyperplasia
- non-caseating granulomas
- skip lesions and transmural ulceration
What are the signs and symptoms of CD?
Symptoms:
-Nausea & vomiting
-Fatigue
-Low-grade fever
-Weight loss
-Abdominal pain
-Diarrhoea (+/- blood)
-Rectal bleeding
-Perianal disease
Signs
-Pyrexia
-Dehydration
-Angular stomatitis
-Aphthous ulcers
-Pallor
-Tachycardia
-Hypotension
-Abdominal pain, mass and distension
What is perianal disease, and what are its symptoms?
Perianal Crohn’s disease refers to a collection of perianal pathology commonly associated with the condition. Skin tags, fissures, fistulae, abscesses and anal canal stenosis may all be seen.
Perianal symptoms are typically non-specific and inspection of the perineum is critical. Symptoms include rectal bleeding, pruritus and pain
What are the extra-intestinal manifestations of CD in the musculoskeletal system, Skin, eyes &mouth, hepatobiliary system, and others?
Musculoskeletal System:
- Type 1 pauciarticular peripheral arthritis related to intestinal disease activity.
- Type 2 polyarticular peripheral arthritis independent of intestinal disease activity.
- ankylosing spondylitis
- sacroilitis
Skin:
- erythema nodosum- reddened, raised, tender nodules
- pyoderma gangrenosum- ulcerating nodules characterised by black (gangrenosum) edges and central pus (pyoderma)
Eyes:
- episcleritis, uvitis, conjunctivitis
Mouth:
- apthous ulcers
Hepatobiliary system:
- PSC
- fatty liver disease
- gall stones
Others:
-Renal calculi
-Osteoporosis
-B12 deficiency
-Pulmonary disease
-Venous thrombosis
-Anaemia
What investigation would you do in CD?
Bedside:
-Observations
-ECG
-Urinalysis
-Stool microscopy, culture & sensitivities + ova, cysts & parasites + C. diff toxin (CDT)
-Faecal calprotectin:
Sensitive marker of intestinal inflammation. Released following degranulation of neutrophils.
Bloods:
-FBC
-LFTS
-Urea & electrolytes
-CRP
-Magnesium
-Haematinics
-Bone profile
-Clotting
Imaging:
Abdominal X-ray: reveals bowel dilatation and perforation in the acute setting. Abdominal USS can be used to assess for wall thickening, free-fluid or abscess formation.
CT: demonstrates bowel wall thickening, bowel obstruction, abscesses, or fistulae. It is good at the assessment of extra-mural complications. Usually completed during acute presentation or looking for complications.
MRI small bowel: evaluation of small bowel and perianal disease. looking at extent of small bowel disease including extent of inflammation and any strictures.
Barium follow through: helps to assess the extent of small bowel disease, particularly strictures.
- Endoscopy- assess the colon & terminal ileum. It provides an opportunity for tissue biopsy with a positive predictive value of 100%.
- surgery- Examination under anaesthetic (EUA): allows the thorough assessment of CD associated perianal fistula’s.
How do you treat CD to induce remission?
In first-time patients or those who develop a flare of CD:
- nutritional alterations
- corticosteroids
In mild-moderate CD:
- Exclusive enteral nutrition over an 8-week period
In mild-moderate ileocecal CD patients:
- budesonide 9mg once daily for 8 weeks
- for patients who fail to respond to this, systemic corticosteroids (prednisolone) should be prescribed for 8 weeks
In moderate-severe patients:
- early introduction of immunosuppressive therapy (azathioprine or methotrexate)
- If patients have evidence of significant and/or extensive disease or other poor prognostic features early introduction of biologic therapy (e.g. infliximab) is recommended.
What can be given to CD patients as maintenance therapy?
- thiopurines (azathiopurine & mercaptopurine)- major side effects can include pancreatitis and hepatotoxicity
- Methotrexate- must check renal and lier function before use. Major side effects include bone marrow suppression, hepatotoxicity, and pulmonary toxicity
- Biologics- infliximad, adalimumab, vedolizumab
Surgical management in the management of CD.
Surgery still forms a key part of management in CD. It is estimated that 8 out of 10 patients will have at least one operation during the course of their disease.
How is surveillance colonoscopy used in the management of CD?
Currently, patients with IBD in the UK are offered surveillance ileocolonoscopy between 6-10 years following diagnosis to screen for dysplasia. Patients with primary sclerosing cholangitis (PSC) are at a particularly high risk of cancer.
