IBD: Ulcerative Colitis

Question 1

What is ulcerative colitis (UC)?

Answer 1

A type of inflammatory bowel disease characterized by diffuse inflammation of the colonic mucosa and a relapsing, remitting course.

Question 2

Briefly describe the macroscopic pathophysiology of UC

Answer 2

It is characterized by diffuse, continuous, superficial inflammation of the large bowel limited to the intestinal mucosa, and usually affects the rectum with a variable length of the colon involved proximally.

Question 3

Briefly describe the microscopic pathophysiology of UC

Answer 3

UC usually involves only the mucosa, with the formation of crypt abscesses and a coexisting depletion of goblet cell mucin.

Further microscopic changes include inflammation of the crypts of Lieberkuhn and abscesses. Ulcerated areas are soon covered by granulation tissue.

Question 4

Give examples of extra-intestinal manifestations of UC

Answer 4

Ulcerative colitis has a number of extra-intestinal manifestations including:

• Uveitis
• Inflammatory arthritis
• Erythema nodosum
• Pyoderma gangrenosum

Question 5

What are the risk factors for UC?

Answer 5

• Family history of IBD
• HLA-B27
• Infection

Question 6

What are the signs of UC?

Answer 6

• Malnurition
• Extraintestinal manifestations (e.g. erythema nodosum and acute arthropathy)
• Abdominal tenderness

Question 7

What are the symptoms of UC?

Answer 7

• Rectal bleeding
• Diarrhoea
• Blood in stool
• Abdominal pain
• Arthritis and spondylitis

Question 8

What investigations should be ordered for UC?

Answer 8

• Stool studies
• FBC
• Comprehensive metabolic panel (inclduing LFTs)
• ESR
• CRP
• Abdominal radiograph
• Flexible sigmoidoscopy
• Colonoscopy
• Biopsies

Question 9

Why investigate stool studies? And what may this show?

Answer 9

• Of all the stool inflammatory tests available, faecal calprotectin is recommended. It is elevated when there is bowel inflammation and correlates with endoscopic and histological gradings of disease severity.
• Negative culture and Clostridium difficile toxins A and B; WBC present; elevated faecal calprotectin

Question 10

Why investigate FBC? And what may this show?

Answer 10

• Variable degree of anaemia, leukocytosis or thrombocytosis

Question 11

Why investigate comprehensive metabolic panel (including LFTs)? And what may this show?

Answer 11

• May show a variety of things:
  
  • Hypokalaemic metabolic acidosis
  • Elevated sodium and urea
  • Elevated alkaline phosphatase
  • Bilirubin
  • Aspartate aminotransferase (AST)
  • Alanine aminotransferase (ALT)
  • Hypoalbuminaemia

Question 12

Why investigate ESR? And what may this show?

Answer 12

• Marker for inflammation
• Variable degree of elevation

Question 13

Why investigate CRP? And what may this show?

Answer 13

• Marker for inflammation
• Variable degree of elevation

Question 14

Why investigate using abdominal ragiograph? And what may this show?

Answer 14

• Used to estimate of the extent of disease because an ulcerated colon usually contains no solid faeces
• Dilated loops with air-fluid level secondary to ileus; free air is consistent with perforation; in toxic megacolon, the transverse colon is dilated to ≥6 cm in diameter

Question 15

Why investigate using flexible sigmoidoscopy? And what may this show?

Answer 15

• Note: findings are as in colonoscopy, but examination is limited to distal colon
• Dilated loops with air-fluid level secondary to ileus; free air is consistent with perforation; in toxic megacolon, the transverse colon is dilated to ≥6 cm in diameter

Question 16

Why investigate using colonoscopy? And what may this show?

Answer 16

• Indicated in patients with UC who are not responding well to treatment, in order to rule out infections (particularly cytomegalovirus and Clostridium difficile) and assess the need for surgery
• Rectal involvement, continuous uniform involvement, loss of vascular marking, diffuse erythema, mucosal granularity and fistulas (rarely seen)

Question 17

Why investigate using biopsies? And what may this show?

Answer 17

• Biopsies should be obtained at the time of endoscopy even if the mucosa appears unremarkable. Biopsies are essential for diagnosis and differential diagoses.
• Continuous distal disease, mucin depletion, basal plasmacytosis, diffuse mucosal atrophy, absence of granulomata and anal sparing