5.4. Intestinal Disease - Crohn's Disease (IBD) Flashcards
What is the Aetiology of Crohn’s Disease?
This is unknown, but it is clear that there is an interaction between several co-factors
What co-factors are thought to cause Crohn’s Disease
- Genetic Susceptibility - This is a Complex Polygenic Disease
- Environmental Factors
- Intestinal Microbiota - The number of Mucosal Adherent Bacteria is Increased
What are the Risk Factors which make up the Genetic Susceptibility to Crohn’s?
- Family History - the largest independent risk factor
- People with mutations of the (Chromosome 16) NOD2 gene - expressed on the Epithelial/Endothelial Cells, and Macrophages
What are the Risk Factors which make up the Environmental Factors for the Susceptibility of Crohn’s?
- Smoking
- NSAID
- Hygiene
- Nutritional Factors
- Phsychological Factors
- Appendectomy
How is Smoking associated with the Aetiology of Crohn’s Disease?
It has been shown to exacerbate the disease
How are NSAID’s associated with the Aetiology of Crohn’s Disease?
This is associated with the Onset and Flaring of the disease
How is Hygiene associated with the Aetiology of Crohn’s Disease?
Good Domestic Hygiene has been shown to be a risk factor - A constantly clean environment may not expose the Intestinal Immune System to (Non-)Pathogenic Organisms
How is Nutrition associated with the Aetiology of Crohn’s Disease?
- Some foods are suggested to play a role but none have been proven
- Breast feeding may provide protection against the developing within offspring
How are Psychological Factors associated with the Aetiology of Crohn’s Disease?
Chronic Stress / Depression increase relapses in patients
How is having had an Appendectomy associated with the Aetiology of Crohn’s Disease?
This increases the Risk of the Disease
What are the Risk Factors which make up the Intestinal Microbiota for the Susceptibility of Crohn’s?
- Intestinal Dysbiosis
- Pathogenic Organisms
- Bacterial Antigens
- A Defective Chemical Barrier
- An Impaired Mucosal Barrier
- Butyrate
How is Intestinal Dysbiosis associated with the Aetiology of Crohn’s Disease?
There is an Altercation in the Bacterial Flora of those with Crohn’s:
- There are Higher Concentrations of Bacteroides and E. Coli
- There are Lower Concentrations of F. Prausnitzii
How are Pathogenic Organisms associated with the Aetiology of Crohn’s Disease?
There is an increase in E. Coli (Intestinal Dysbiosis) adherence to the Ileal Epithelial Cells, which has been shown to be related to Invasion of the Mucosa, of people with Crohn’s Disease exacerbations
How are Bacterial Antigens associated with the Aetiology of Crohn’s Disease?
There is an increase of Bacteria which exert their influence by Ligands, which interact with Host-Pattern Receptors in Crohn’s Disease exacerbations
How is a Defective Chemical Barrier associated with the Aetiology of Crohn’s Disease?
Evidence suggests a decrease in Human Intestinal Defensin “Alpha-Defensin-1” (HD-1) as well as a lack of induction of other Defensins can lead to Crohn’s Disease exacerbations
How is a Impaired Mucosal Barrier associated with the Aetiology of Crohn’s Disease?
This can explain the presence of unusual and potentially pathogenic bacteria, which can lead to Crohn’s Disease exacerbations
What is Butyrate?
A type of fatty acid which helps with Intestinal Function
How is a Butyrate associated with the Aetiology of Crohn’s Disease?
- A Sulphate-Producing Bacteria which increases Luminal Levels of Hydrogen Sulphide
- This decreases Butyrate Oxidation in the Colonic Mucosa
- This leads to Mucosal Inflammation which can precede Crohn’s Disease exacerbations
What is the Pathology of Crohn’s Disease?
This is a Chronic Inflammatory Condition
Where can Chron’s Disease effect?
Any part of the Alimentary Tract - From the Mouth to the Anus
Where does Chron’s Disease tend to effect?
- The Terminal Ileum
2. The Ascending Colon
Why does the inflammation in Chron’s Disease occur?
Due to the Mucosal Immune System exerting an inappropriate Response to Luminal Antigens (e.g. Bacteria). These Bacteria may enter into the Mucosa via a Leaky Epithelium
What are the different presentation areas which Chron’s Disease can involve?
- One small area of the Gut
- Multiple areas, with Relatively normal Bowel between them
- The Whole Colon, sometimes without Microscopic Small Bowel involvement
What is the name of the Area of Normal Bowel between 2 effected areas?
Skip Lesions
What is the name of Crohn’s Disease which effects the Whole Colon/
Total Collitis
What are the Macroscopic Changes which occur in Crohn’s Disease?
- Thickened (often Narrowed) Bowel
- Aphthoid Ulceration - usually seen on Colonoscopy (Early Sign)
- Deep Ulcers / Fissures in the Mucosa (Later Sign) - producing a Cobblestone Appearance
- Fistulae and Abscesses - which reflect Penetrating Disease
What are the Microscopic Changes which occur in Crohn’s Disease?
- Inflammation which extends through all layers of the Bowel (Transmural)
- Increase in Chronic Inflammatory Cells
- Lymphoid Hyperplasia
- Ganulomas may be present - Non-caeseating Epithelioid Cell Aggregates with Langerhan’s Giant Cells
What are the Clinical Features of Crohn’s Disease?
Other than Macro/Microscopic Appearance
- Diarrhoea with Blood
- Abdominal Pain
- Weight Loss
- Constitutional Symptoms (Malaise, Lethargy, Fever)
- Nausea and Vomiting
Why does Diarrhoea with Blood occur?
Due to the Ulceration throughout the Alimentary Tract
What is the Abdominal Pain described as?
Colicky (Suggesting Obstruction) without special characteristics
Why does Weight Loss occur?
- Due to Anorexia
2. Alongside Anaemia
How might an Emergency Presentation of Crohn’s present?
Acute Right Iliac Fossa Pain - Mimicking Appendicitis
What is a common complication of Crohn’s Disease?
(Peri-)Anal Sypmtoms which often precede Colonic / Small Intestinal Symptoms
What investigations are required in Crohn’s Disease?
- Upper G.I. Endoscopy / Colonoscopy / Capsule Endoscopy
- Abdominal Ultrasound / X-Ray / CT Scan
- Stool Culture
- Blood Tests
What is the purpose of the Upper G.I. Endoscopy / Colonoscopy / Capsule Endoscopy?
To visualize the Intestinal Lumen throughout the Alimentary Tract
What is the purpose of the Abdominal Ultrasound / X-Ray / CT Scan?
To visualize the Outside Structure of the Alimentary Tract
What is the Upper G.I. Endoscopy / Colonoscopy / Capsule Endoscopy looking for?
- Macroscopic Changes
2. Characteristic Skip Lesions
What is the purpose of the Stool Culture?
To monitor the Disease Activity
What is the Stool Culture looking for?
- Clostridium Difficile Toxin assay when Diarrhoea is present
- Faecal Calprotectin and Lactoferrin are raised in Active Colonic Disease
What is the Purpose of the Blood Tests?
To monitor the Disease Activity
What are the Blood Tests looking for?
- Anaemia - may occur with an Iron/Folate deficiency (Rarely Vitamin B12)
- Hypoalbuminaemia - only present in sever cases
- Serum Inflammatory Markers (CRP and ESR)
- White Cell Count
- Platelet Count
- Blood Culture - If septicaemia is suspected
What is the aim of management of Crohn’s Disease?
- To induce clinical remission
- To maintain clinical remission
- To achieve Mucosal healing to prevent complications
What general measure can be taken to treat Crohn’s Disease?
Smoking Cessation
What is used for the Induction of Remission?
- Glucocorticosteroids (ORal Prednisolone)
2. Enteral Nutrition
What is Enteral Nutrition?
A low fat and linoleic content diet as a sole source of diet for 28 days
What is used for the Maintenance of Remission?
- Conventional Therapies:
a) Steroid Sparing Agent - Azathioprine
b) 6MP (Mercaptopurine
c) Methotrexate - Anti-TNF antibodies (Infliximab)
What surgery is done to badly effected parts of the G.I. Tract?
Proctocolectomy - the removal of only the effected part
What is the term given to Colitis which cannot be distinguished between Crohn’s Disease and Ulcerative Colitis origin?
Colitis of Unknown Type and Aetiology (CUTE)
What treatment might people with Mild Disease get?
Symptomatic Treatment
