SM_163b: Clinical Features of Colonic Disorders

Question 1

Colon functions are ____, ____ and ____

Answer 1

Colon functions are absorption, recycling and secretion, and stool formation and defecation

• Colon has segmental and propagated activity

Question 2

Diveticulosis is the presence of ____, which are ____

Answer 2

Diveticulosis is the presence of diverticula, which are sac-like protrusions of the colonic wall

• May be symptomatic or asymptomatic

Question 3

Diverticular diseases are ____

Answer 3

Diverticular diseases are clinically significant and symptomatic diverticulosis

• Diverticular bleeding
• Diverticulitis
• Segmental colitis associated with diverticula (SCAD)
• Symptomatic uncomplicated diverticular disease

Question 4

Describe anatomy and pathophysiology of diverticular diseases

Answer 4

Anatomy and pathophysiology of diverticular diseases

• LaPlace’s Law: P = kT/R
• True diverticulum: involves herniation of the entire bowel wall (i.e. all layers)
• False / pseudo-diverticulum: mucosa protrudes through muscularis propria

Question 5

Diverticular bleeding presents as ____

Answer 5

Diverticular bleeding presents as painless hematochezia due to segmental weakness of the vasa recta associated with a diverticulum

• 10% of patients with diverticulosis
• Most common cause of hematochezia in > 60 years
• Risk factors for bleeding: HTN, atherosclerosis, NSAID use

Question 6

Diverticular bleeding most often occurs in the ____ and the majority of bleeds are ____

Answer 6

Diverticular bleeding most often occurs in the right colon and the majority of bleeds are self-limited

• Localization: colonoscopy (diagnostic and therapeutic), angiography (diagnostic and therapeutic), tagged RBC scan (diagnostic ), and segmental colonic resection
• Treatment: supportive care, colonscopy, angiography with embolization, surgical resection

Question 7

____ is inflammation of the diverticula

Answer 7

Diverticulitis is inflammation of the diverticula

• Obstructed diverticula opening

Question 8

Diverticulitis presentation may be ____ or ____

Answer 8

Diverticulitis presentation may be uncomplicated or complicated

• Uncomplicated: abdomianl pain, fever, leukocytosis, anorexia
• Complicated: abscess, macro-perforation, stricture, fistula

Question 9

Diverticulitis diagnosis often involves ____, ____, and ____

Answer 9

Diverticulitis diagnosis often involves distention / tenderness with palpation / signs of peritonitis, leukocytosis, and CT scan with presence of diverticula / thickened colonic wall > 4 mm, inflammation within pericolic fat ± fluid collection

• CT scan is diagnostic

Question 10

Describe the Hinchey classification for diverticulitis

Answer 10

Hinchey classification for diverticulitis

• I: inflammation + pericolic abscess or phlegmon (confined)
• II: inflammation + retroperitoneal or pelvic abscess (distant)
• III: inflammation + purulent peritonitis
• IV: inflammation + focal peritonitis

Question 11

Prior uncomplicated attacks ___ predict high incidence or higher severity of recurrence of diverticulitis

Answer 11

Prior uncomplicated attacks do NOT predict high incidence or higher severity of recurrence of diverticulitis

• Need colonscopy following first attack
• Uncomplicated diverticular disease: bowel rest, supportive care, ± antibiotics
• Complicated diverticular disease: bowel rest, IV antibiotics ± abscess drainage ± surgery

Question 12

Diverticulitis diet therapy involves ____, ____, ____, and ____

Answer 12

Diverticulitis diet therapy involves high fiber diet, physical activity, reducing obesity, and reducing fat and red meat

Question 13

Segmental colitis associated with diverticula (SCAD) is ____

Answer 13

Segmental colitis associated with diverticula (SCAD) is inflammation in the interdiverticular mucosa without involvement of the diverticular orifices

• Possibly related to mucosal prolapse, fecal stasis, and localized ischemica or alterations in the microbiome

Question 14

Symptomatic uncomplicated diverticular disease (SUDD) is ____

Answer 14

Symptomatic uncomplicated diverticular disease (SUDD) is persistent abdominal pain attributed to diverticula in the abscence of overt colitis or diverticulitis

• Symptoms + wall thickening on CT without inflammatory changes or mucosal abnormalities on colonoscopy
• Abnormal motility ± visceral hypertensitivity play a role in symptom perception

Question 15

Ischemic colitis is ___

Answer 15

Ischemic colitis is insufficient perfusion to the colon that produces ischemic tissue injury

• Ischemia: reduction in blood flow to a level that is insufficient for delivery of oxygen and nutrients required for cellular metabolism
• Older adults, female > male

Question 16

Ischemic colitis may occur due to ____ or ____

Answer 16

Ischemic colitis may occur due to non-occlusive ischemia or embolic / thrombotic occlusion (arterial or venous)

Question 17

Describe non-occlusive ischemia as a cause of ischemic colitis

Answer 17

Non-occlusive ischemia as a cause of ischemic colitis

1. Chronic progressive hypoperfusion
2. Collateral blood flow allows perfusion
3. Mucosal infarction limited to muscularis mucosae, watershed areas affected

Causes: cardiac failure, shock, dehydration, extreme exercise, use of vasoconstrictive drugs

Question 18

Describe embolic / thrombotic occlusion (arterial or venous) as a cause of ischemic colitis

Answer 18

Embolic / thrombotic occlusion (arterial or venous) as a cause of ischemic colitis

1. Acute compromise of a major vessel
2. Infarction
3. Mural infarction of mucosa / submucosa or transmural infarction

Causes: severe atherosclerosis, aortic aneurysm, hypercoagulable states, oral contraceptive use, embolization of vegetations or atheromas, aortic instrumentation, vasculitis

Question 19

Ischemic colitis may involve ____ and ____ injury

Answer 19

Ischemic colitis may involve hypoxic and reperfusion injury

• Hypoxic: at onset of vascular injury, minimal injury at surface but can progress to transmural necrosis
• Reperfusion injury: restoration of blood supply, leakage of bacterial products / free radical production / neutrophil infiltration / release of inflammatory mediators

Question 20

Ischemic colitis presents as ____ and ____

Answer 20

Ischemic colitis presents as sudden onset abdominal cramping / tenderness / urgency and mild/moderate amounts of rectal bleeding / blood diarrhea

1. Hyperactive phase
2. Paralytic phase
3. Shock phase

Question 21

X-ray / CT of ischemic colitis may show ____

Answer 21

X-ray / CT of ischemic colitis may show thumbprinting (submucosal edema) pneumoatosis (air within the bowel)

• Labs
  Rule out infectious or inflammatory causes and mesenteric ischemia (affecting small bowel)
• High index of suspicion
• Treatment: supportive care, antibiotics, antithrombotic therapy, surgery, endovascular intervention

Question 22

Intestinal ischemia may result from ____ or ____

Answer 22

Intestinal ischemia may result from colonic ischemia or small bowel / mesenteric ischemia

• Both can involve superior mesenteric artery

Question 23

Describe colonic ischemia

Answer 23

Colonic ischemia

• > 60 years
• Acute precipitating cause rare
• Do not appear severely ill
• Mild abdominal pain / mild tenderness
• Rectal bleeding / bloody diarrhea
• Colonscopy for diagnosis

Question 24

Describe small bowel / mesenteric ischemia

Answer 24

Small bowel / mesenteric ischemia

• Age varies
• Acute precipitating cause typical
• Patients severely ill
• Pain severe / initially mild tenderness
• Bleeding uncommon until late
• Angiography or CT for diagnosis

Question 25

Microscopic colitis is ____

Answer 25

Microscopic colitis is chronic inflammatory disease of the colon characterized by chronic water diarrhea with normal appearing mucosa on colonoscopy

• Older women, associated with other autoimmune diseases

Question 26

Microscopic colitis diagnosis is ____

Answer 26

Microscopic colitis diagnosis is histologic

• Lymphocytic colitis: intraepithelial lymphocytic infiltrate (> 20/HPF)
• Collagenous colitis: colonic subepithelial collagen band (> 10 um)

Question 27

____ and ____ are risk factors for microscopic colitis

Answer 27

Medications and smoking are risk factors for microscopic colitis

• NSAIDs, PPIs, ranitidine, sertraline

Question 28

Microscopic colitis presents as ____, biopsies should specifically focus on the ____, and treatment goal is to ____

Answer 28

Microscopic colitis presents as chronic watery diarrhea, biopsies should specifically focus on the right colon and rectosigmoid, and treatment goal is to achieve symptomatic improvement