Lower GI Autoimmune: Ulcerative Colitis, Crohns, Coeliac Disease, Intestinal Obstruction, Mesenteric Ischemia

Question 1

Crohns vs UC

-causes

Answer 1

Crohns - triggered by pathogens

• genetic - NOD2 pathogen recognition proteien
• environmental - smoking, refined sugars

UC - inflammatory response to colonic bacteria
-SMOKING, APPENDECTOMY PROTECTIVE

Question 2

Crohns

-pathophysiology and presentation

Answer 2

Full thickness inflammation - TERMINAL ILEUM + COLON

• inflammation => abdo pain
• chronic => thickens wall, fistula, strictures
• skip lesions => diarrhoea, no tenesmus

Terminal ileum - most commonly affected

• reduced B12, fat uptake => macrocytic megaloblastic anemia, steatorrhea
• increased unabsorbed fat binds to Ca instead of oxalate => oxalate renal stone

Reduced ability to absorb nutrients => weight loss, malnutrition

Question 3

UC

-pathophysiology and presentation

Answer 3

Rectum => extends proximally to terminal ileum

• continuous mucosal inflammation => crypt abscess, goblet loss, bloody tenesmus diarrhoea, crampy pain
• thinning colonic wall => toxic megacolon, perforation

Question 4

ExtraGI manifestations of IBD

Answer 4

A ESCAPE
Apthous ulcers
Erythema nodosum
Sclerosing cholangitis (UC)
Clubbing
Arthritis
Pyoderma gangrenosum
Extraocular (uveitis UC, episcleritis C)

Question 5

Diagnosis and investigations for Crohns and UC

Answer 5

Fecal calprotectin - GI inflammatory marker but not specific

Enemas

• Crohns - strictures, fistulas, proximal bowel dilation
• UC - no haustrations, drainpipe

Definitive - endo/colonoscopy with biopsy to confirm

• Crohns - cobblestoning, skip lesions, non caseating granulomas
• UC - pseudopolyps, crypt abscess,

Question 6

Management of Crohns and UC

• acute
• remission

Answer 6

Crohns - Acute
-CS
Crohns - Remission
-Azathiopurine or mercatopurine

UC - Acute
-5ASA if mild
-CS if severe 
UC - Remission
-5ASA if mild
-thiopurine if severe

Can escalate to biologics if not controlled
-infliximab - TNFa

Question 7

Small bowel obstruction

• most common causes
• presentation
• investigations, diagnosis

Answer 7

MOST COMMON - adhesions from past surgery
Hernias
Thickened gut wall from Crohns

Diffuse abdo pain
N+V
Complete constipation - no farts, stools
Abdo distension
Tinkling bowel sounds
Symptoms associated with complications

Definitive - CT
1st line - Abdo Xray
-distended bowel loops (3+) with fluid level
-valvulae coniventes cross bowel completely

Question 8

Small and large bowel obstruction

-management

Answer 8

Conservative - drip and suck

• IV fluid resus, analgesia, antiemetics
• NG tube suction to decompress bowel
• monitor fluid balance with catheter

If no past surgery, unlikely to resolve with conservative
Surgery - laparotomy if
-no resolution within 2 days
-complications
-cause that needs surgical intervention

Question 9

Large bowel obstruction

• most common causes
• presentation
• diagnosis, investigations

Answer 9

MOST COMMON - tumours especially in distal colon due to narrower lumen

• volvulus
• diverticular disease

Diffuse abdo pain
N+V
Complete constipation - no farts, stools
Abdo distension
Tinkling bowel sounds
Symptoms associated with complications

Definitive - CT
1st line - AXR
-dilated bowel loops (6+ distal, 9+ proximal)
-haustra (halfway)

Question 10

Coeliac disease
- causes
- pathophysiology and presentation
- associated conditions

Answer 10

AI response to gluten
HLA DQ2-8

Chronic inflammation in presence of gluten - crampy pain,

Jejenum most commonly affected - folate uptake affected more than Fe (duodenunm) or B12 (ileum) => anemia, peripheral neuorpathy, hyposplenism
Malabsorption => diarrhea, weight loss, steatorrhea

High associations with

• T1DM, AI thyroiditis
• dermatitis herpetiformis - itchy, vesicles on extensors from IgA deposition

Question 11

Coeliac disease

-diagnosis, investigations

Answer 11

Ensure they are currently eating gluten
Serology - TTG IgA/G, endomyseal IgA
DEFINITIVE - biopsy 
-villous atrophy, crypt hyperplasia, high lymphocytic infiltration
HLA DQ2-8 testing

Question 12

Coeliac disease management

Answer 12

Gluten free diet - no wheat, rye, barley

Supportive

• nutritional support
• manage associated conditions

Question 13

Mesenteric ischemia

• pathophysiology
• presentation

Answer 13

Inadequate blood flow to mesenteric vessels supplying GI tract
-often due to embolus (AF, IE) or atherosclerosis

Abdo pain after eating, sudden onset and out of keeping with physical exam findings
-soft non tender abdo, no guarding
N+V

Hx of AF, peripheral vasculopathy

Question 14

Mesenteric ischemia
- diagnosis
- investigations

Answer 14

FBC - Hb high, WCC high due to plasma loss
VBG - HIGH LACTATE (HYPOPERFUSION)

CT abdo - DEFINITIVE
-may need CT angiography to locate clot

Question 15

Mesenteric ischemia
- management
- complications

Answer 15

Emergency laparotomy with ABx - remove necrotic bowel

Supportive - IV fluids, analgesia, broad spec, LMWH

Peritonitis - septic, guarding, MOF

Question 16

IBS

• presentation
• diagnosis, investigations

Answer 16

IBS should be considered if - 6 months of

• Abdo pain
• Bloating
• Change in bowel habit

Positive diagnosis if -
-abdo pain relieved by defecation AND 2 of
-straining, urgency, incomplete empyting
-abdo bloating
symptoms worsened by eating
-mucus

Investigations to rule out other possible causes

• FBC
• ESR, CRP
• coeliac screen