Inflammatory Bowel Disease

Question 1

Importance of micro and macro anatomy for IBD

Answer 1

• Crucial for accurate diagnosis and management
• Allows for recognition of abnormalities: inflammation, strictures, ulcers, guiding treatment decisions, monitoring disease progression

Question 2

What is IBD? Difference between IBD and IBS

Answer 2

IBD: group of chronic inflammatory conditions of GI: chrons, ulcerative colitis, characterised by recurrent inflammation and tissue damage in digestive system
IBS: functional disorder characterised by abdominal pain, bloating and changes in bowel habits wihtout inflammation or tissue damage

Question 3

What is the GI tract? Functions of organs in GI tract.

Answer 3

GI Tract: aka digestive tract, system of organs for processing food and nutrients in the body
1. Mouth: Entry point for food where chewing and initial digestion begin. The pharynx is a muscular tube that serves as a passageway for both food and air, connecting the nasal cavity and mouth to the esophagus and larynx.
2. Esophagus: Tube that transports food from the mouth to the stomach.
3. Stomach: Organ that mixes food with digestive juices, breaking it down into smaller particles.
4. Small Intestine: Site of nutrient absorption from digested food.
5. Large Intestine (Colon): Absorbs water and salts, forming waste into feces. The ileocecal sphincter controls the passage of food from the small intestine to the large intestine, and the sigmoid colon stores waste before it leaves the body.
6. Rectum: Stores feces before elimination.
7. Anus: Exit point for waste from the body.

Question 4

Accessory structures of GI tract and their function

Answer 4

• Aid digestion/ food breakdown
  1. Liver: Produces bile, which aids in fat digestion and detoxification.
  2. Pancreas: Secretes digestive enzymes and insulin to regulate blood sugar levels.
  3. Gallbladder: Stores and concentrates bile produced by the liver before releasing it into the small intestine during digestion.

Question 5

Describe the features of the histology of the small intestine and their function

Answer 5

• Lacteals: Small lymphatic vessels in the small intestine that absorb dietary fats.
  Venule: Small blood vessel that carries deoxygenated blood back to the heart.
• Arteriole: Small branch of an artery that carries oxygenated blood away from the heart.
• Lymphatic vessels: Thin tubes that carry lymph fluid, containing white blood cells, throughout the body.
• Villi of small intestine: Finger-like projections in the small intestine that increase surface area for nutrient absorption
• Lymphatic nodule: Small clusters of immune cells in the intestinal lining that help protect against infections.
• Blood capillaries: Tiny blood vessels that exchange nutrients, oxygen, and waste products between blood and tissues.
• Myenteric plexus: Network of nerves in the muscular layers of the gastrointestinal tract that regulates gut motility.
• Serosa: Outermost layer of the digestive tract composed of connective tissue and epithelial cells, providing support and protection.

Question 6

Aetiology & Definition of IBD

Answer 6

• Definition: Chronic IBD, ulcers in lining of colon and rectum
• Aetiology: Auto immune: immune system mistakenly attacks healthy GI tract cells)
  Genetic predisposition: family history of UC shows higher risk
  Environmental Factors: diet, smoking, stress, exposure to particular infections/ pollutants can trigger/ worsen UC
• Immune dysregulation: can cause chronic inflammation in colon and rectum contributing to disease pathogenesis

Question 7

Chrons Disease Aetiology & Definition

Answer 7

Definition: Chronic Inflammatory Bowel Disease
- Can affect any part of GI from mouth to anus, most common sites being small intestine and colon

Aetiology: Immune mediated but not strictly auto immune: can instead result from inflammation and immune activation due to:

genetic predisposition ( family history)
Environmental factors: Diet, smoking, stress, exposure to certain infections/ pollutants
Immune Dysregulation
alterations in gut microbiota and disruptions in intestinal barrier function

these can cause chronic inflammation and tissue damage
exact cause is unknown

Question 8

Pathogenesis of Ulcerative Colitis

Answer 8

• Immune Dysregulation leading to inflammation: mediated by cytokines/ immune cells perpetuating a cycle of tissue injury ad repair. Cytokines regulate immune responses by facilitating communications between cells
• Involvement limited to mucosa: affects innermost layer of colon lining primarily: Bloody Diarrhoea, abdominal pain
  Factors Triggering UC development: variations in certain genes related to the immune system/ inflammation. Alterations in gut microbia and disruptions in intestinal barrier function contribute to UC pathogenesis.

Gut microbia are microorganisms residing in the GI tract with a curical role in various physiological processes such as digestion, immune function, protection against pathogenesis. Disruption to their balance/ composition linked to various health conditions including inflammatory bowel disease, metabolic disorders, immune-related disorders

Question 9

Pathogenesis of Chron’s Disease

Answer 9

• combination of genetic and enrivonmental facotrs triggering abnormal immune response
• causes transmural inflammation affecting any part of the GI tract
• can result in skip lesion formation ( areas of inflammation interspersed with healthy tissue) contributing to patch distribution of infammation seen in Crohns disease

Question 10

UC Histopathology

Answer 10

• Confined to the colon
• Inflammation limited to mucosa, doesn’t affect muscle wall
• UC shows continuous inflammation without areas of unaffected mucosa
• Biopsy: Distortion of Crypt architecture, Inflammation of crypts (cryptisis), crypt abcesses, ulceration, inflammatory cells in lamina propria

crypt: tiny pit or depression in intestine lining

Question 11

Histopathology of Chron’s Disease

Answer 11

• Can involve any part of the GI tract
• Inflammation in CD involves full thickness of mucosa and wall ( transmural)
• Biopsy:
• chronic inflammation in the digestive tract, with areas showing increased immune cells like plasma cells and lymphocytes.
• Patches of severe inflammation along with ulcers and erosions, often occurring in a patchy pattern known as “skip lesions.”
• Causes discontinuous inflammation of the GI tract – skip lesions. Inflammation of the full thickness of the bowel wall
• can lead to the formation of abnormal structures like granulomas, fissures, and fistulas.
• Granulomas: small collections of immune cells that form in response to chronic inflammation.
• Fissures: tears or openings in the lining of the intestine, and fistulas are abnormal connections or passages between different parts of the intestine or between the intestine and other organs.
• Over time, sub mucosal fibrosis and neuromuscular hyperplasia of the submucosa may occur in the deeper layers of the intestine, causing scarring and thickening of the tissue in the intestine

Question 12

Ulcerative Colitis Symptoms and Diagnosis

Answer 12

• UC forms ulcerative lesions in the colon starting around the anus and moving proximally in a continual lesion
• Symptoms: Blood diarrhoea, abdom pain, urgency, tenesmus, weight loss, fatigue, extra intestinal manifestations (rare)
  tenesmus: sensation of needing to pass stool even when bowls are empty
• Diagnosis: Clinical ( signs and symptoms), radiological features, endoscopy, biopsy

Question 13

UC : Radiological Features

Answer 13

-Loss of Haustral markings: Due to diffuse inflammation and mucosal ulceration in the colon.
-Mucosal friability: Mucosal surface may appear rough or irregular due to inflammation and ulceration.
-Toxic megacolon: Severe inflammation can lead to colonic dilation and a risk of perforation, which may be evident on imaging.
-Pseudopolyps: Areas of intact mucosa surrounded by ulceration, giving a polyp-like appearance.
-Lead pipe appearance: Loss of colonic haustration leading to a smooth appearance on barium enema. A barium enema is a diagnostic imaging test that uses a contrast material containing barium to visualize the colon and rectum on X-ray

Question 14

Crohn’s Disease symptoms

Answer 14

Symptoms: Abdominal pain, diarrhoea ( may be bloody), weight loss, fatigue
Extra intestinal sites:
- Ocular manifestations ( Uveitis, recurrent iritis, and episcleritis),
-dermal manifestations ( erythema nodosum, pyoderma gangrenosum, sweet syndrome)

• inflammatory seronegative arteriopathies ( group of inflammatory joint diseases characterised by inflammation in joints and surrounding tissues. do not typically produe antibodies detected in blood tests so referred to as seronegative
  e.g sacroiliitis, ankylosing spondylitis, psoriatic arthritis, reactive arthritis)

-liver and bile ducts can be involved ( indicine of sclerosing cholangitis increased by 10% with Chrons disease history)
- primary sclerosing cholangitis: chronic disease characterised by inflammation and scarring of bile ducts leading to liver damage and potential complications such as cirrhosis and liver failure

Question 15

Crohns’ Disease Diagnosis

Answer 15

• Radiological features ( cobblestone appearance, string sign)
• Clinical picture between UC and Crohns disease can be difficult to deciphers ( biopsy is key)
• Cobblestone appearance: lining of your intestine looks bumpy and uneven, similar to the surface of cobblestone streets.
• String sign: intestine becomes narrower than usual because of swelling and inflammation. looks like a thin string on imaging tests, showing that the intestine is narrowed by inflammation.
• Indeterminate Colitis: Pathogenesis. Histopathology, signs, symptoms and diagnostic findings may not clearly fit criteria for either ulcerative colitis or crohns disease
• Distinguishing between ulcerative colitis (UC) and Crohn’s disease based solely on clinical symptoms can be challenging. Biopsies provide detailed information about the patterns of inflammation, tissue damage, and other features that help differentiate between UC and Crohn’s disease, guiding appropriate treatment decisions.

Question 16

Treatment of UC

Answer 16

• various medications to reduce inflammation and modulate the immune response, along with experimental therapies like faecal bacteriotherapy and helminth therapy.
• Aminosalicylates, Corticosteroids, Immunomodulators, and Biologics: different types of medications used to treat ulcerative colitis by reducing inflammation and helping the immune system.
• Faecal Bacteriotherapy (“Poo Transplant”): experimental treatment where healthy bacteria from someone else’s poop are put into the colon to try and make the gut healthier.
• Experimental Helminth Therapy: parasitic worms used to change how the immune system works.
• Maintaining remission is essential to manage symptoms and prevent disease progression.
• Surgical options may be considered in severe cases or when complications arise: colectomy and IPAA offering relief and improved quality of life for some patients.
• Ileal pouch-anal anastomosis: surgical procedure that creates an internal pouch using part of the small intestine, which is then connected to the anus, allowing stool to pass normally without a colon.

Question 17

Treatment for Crohn’s Disease and surgery for palliative care

Answer 17

-lifestyle modifications, including dietary changes and stress management,
- corticosteroids to reduce inflammation,
- antibiotics to treat infections,
- immunosuppressants or biologics to modulate the immune response.

• In cases of severe or refractory disease, surgery may be necessary, aiming to remove the affected portion of the intestine to alleviate symptoms and complications like fibrosis and strictures.
  Ileostomy: diverting waste into a bag and providing relief from inflammation
  This is palliative rather than curative, as the condition can recur in other parts of the gastrointestinal tract.
  Palliative care aims to manage pain, alleviate distressing symptoms, provide emotional support, and enhance comfort to the patient.

Question 18

Link b/w chronic inflammation and cancer initiation
Methods of surveillance for management of long-standing IBD

Answer 18

• Chronic inflammation as a precursor to tissue damage and genetic mutations promoting transformation of normal cells intro precancerous/ cancerous cells:
  Long term risks associated with untreated/poorly managed IBD:
• Dysplasia: presence of abnormal cells that may progress to cancer.
• Colorectal cancer: IBD patients have an increased risk of developing colorectal cancer compared to the general population.
• Strictures and narrowing of the intestine: Chronic inflammation in UC can lead to scarring and narrowing of the colon, known as strictures, which may cause bowel obstruction and necessitate surgical intervention.
• Perforation and abscess formation: Severe inflammation and ulceration can result in perforation of the colon’s wall or the formation of abscesses, requiring urgent medical attention.
• Chronic inflammation in Crohn’s disease can lead to the formation of strictures (narrowing of the intestine), fistulas (abnormal connections between organs) Colo-vesicle, Colo-vaginal, Colo-ileal, Colo-colic , and abscesses (collections of pus), requiring medical or surgical intervention.
• Osteoporosis and Osteopenia: Chronic inflammation in IBD can lead to bone loss, increasing the risk of osteoporosis and osteopenia. Osteopenia is characterized by reduced bone mineral density
• Nutritional deficiencies: Malabsorption, dietary restrictions, and inflammation-related metabolic changes can contribute to nutritional deficiencies in IBD patients, such as iron deficiency anemia, vitamin B12 deficiency, and calcium/vitamin D deficiency.
• Surveillance: vital in managing long-standing inflammatory bowel disease (IBD) , allows for the early detection of complications such as strictures, fistulas, or dysplasia, thereby facilitating timely intervention and preventing disease progression. Imaging modalities such as colonoscopy, MRI, or CT scans provide detailed visualization of the gastrointestinal tract, aiding in the assessment of disease activity, monitoring treatment response, and guiding therapeutic strategies.