Gen Surg: Benign diseases of colon

Question 1

Diverticulum vs diverticulosis vs diverticulitis.

Answer 1

Diverticulum: sac-like protrusion of colonic wall due to high pressure in the lumen and colonic wall defects (usually sigmoid). Not actually ‘true diverticulum’ since involves mucosal herniation rather than full wall thickness.

Diverticulosis: presence of multiple false diverticula. Asymptomatic in most. May have painless diverticular bleeding.

Diverticulitis: Inflammation secondary to micro or macro-perforation of a single diverticulum. Acute abdominal pain, LLQ mass and tenderness, leukocytosis, fever. May ahve localized inflammation (sealed perforation) vs feculent perforation (free perforation). May develop complications including fistula.

Question 2

Risk factors for diverticular disease

Answer 2

High fat/red meat diet, obesity, low fiber diet, smoking

Question 3

Uncomplicated vs complicated diverticulitis

Answer 3

Uncomplicated: diverticula in absence of complications.
Complicated: abscess formation, obstruction, fistula, perforation, peritonitis, stricture.

Question 4

Hinchey classification for diverticulitis (inc tx)

Answer 4

Hinchey 1: Phlegmon/small pericolic abscess (localized colonic abscess). Tx w/ medical mgmt.
Hinchey 2: large abscess/fistula, expands into pelvis. Tx w/ abscess drainage, resection +/- primary anastamosis.
Hinchey 3: Purulent peritonitis/ruptured abscess. Tx Hartmann procedure.
Hinchey 4: Feculent peritonitis. Hartmann procedure.

Question 5

Describe non-operative mgmt of diverticulitis

Answer 5

NPO, IVF, IV CTX + flagyl. Order colonoscopy after acute episode resolved.

Question 6

Indications for surgical mgmt of diverticulitis

Answer 6

Unstable patient with peritonitis, Hinchey 3-4, complications such as free air, peritonitis, abscess, fistula, obstruction, hemorrhage.

Question 7

DDx for diarrhea

Answer 7

Acute: infectious, inflammatory, ischemia, drugs/toxins, metabolic (e.g. hyperT4).
Chronic: IBD, IBS, chronic ischemic bowel, metabolic.

Question 8

Lab/imaging workup of colitis

Answer 8

H+P, labs (CBC, lytes, renal fxn), stool C+S, O+P, C diff PCR. CT vs CT angiogram vs colonoscopy.

Question 9

Crohn’s vs UC

Answer 9

UC
Diarrhea: common
Rectal bleeding: very common
Abdo pain: less common
Fever: uncommon
Tenesmus: common
Complications: toxic megacolon
Location: isolated to large bowel, starts at rectum, confluent.
Pathology: mucosal, tiny serrations, coarse mucosa, superficial ulceration, pseudopolyps.
Recurrence post-op: none post-colectomy
Colon cancer risk: increased expect in proctitis.

Crohn’s:
Diarrhea: less severe
Rectal bleeding: infrequent
Abdo pain: post-prandial/colicky
Fever: common
Tenesmus: uncommon
Complications: strictures, fistula, perianal disease
Location: Involves any part of GI tract, skip lesions
Pathology: Transmural, longitudinal ulcers, transverse ridges, cobblestoning, thickened bowel wall, granulomas.
Recurrence post-op: common due to skip lesions.
Colon cancer risk: increased if <30% colon involved.

Question 10

Describe the blood supply to the colon

Answer 10

Superior mesenteric artery: provides blood supply for ampulla of vater to splenic flexure. Gives off the jejunal and ileal arteries to ileum. Gives off ileocolic and right colic arteries to ascending colon and middle colic artery to transverse colon.

Inferior mesenteric artery: Gives off left colic, sigmoid and superior rectal arteries. Supplies the colon from the splenic flexure to distal sigmoid.

Question 11

Etiology of colonic ischemia

Answer 11

Arterial occlusion (e.g. SMA occlusion. RF = Afib, cardiac disease, arterial emboli, hypercoagulable state).

venous occlusion (RF: portal HTN, intraabdominal inflammation, trauma/bowel surgery, hypercoagulable state, CKD).

hypoperfusion (e.g. shock)/vasoconstriction,

non-occlusive mesenteric ischemia (ischemic colitis).

Question 12

Symptoms of bowel ischemia

Answer 12

Pain out of proportion to exam. Pt unwell with fever, tachycardia, peritonitis.

Patho: ischemia –> anaerobic metabolism –> acidosis –> hyperpersitalsis. Initial cramping pain –> ischemic pain. Intense, constant, does not change with palpation and no rigidity. May have diarrhea.

Question 13

Investigations and findings for bowel ischemia

Answer 13

Labs: CBC, lytes, Cr, Lactate
CT eneterography or angiogram.
CT findings may show pneumotosis intestinalis (air in the bowel wall), portal venous gas, thickening of bowel wall, areas of bowel not enhancing.

Question 14

Mgmt of IBD

Answer 14

Lifestyle/diet: smoking cessation

Medical:
Anti-diarrheals: Loperamide, diphenoxylate, codeine.
5-ASA: for UC. E.g. sulfasalazine, mesalamine.
Antibiotics: Cipro/flagyl for perianal Crohn’s.
Steroids: prednisone PO, methylpredisolone IV if severe.
Immunosuppressives: 6-MP, Imuran, MTX.
Biologics: infliximab, adalimumab (Humera), TNF-a.

Surgical:
Segmental colectomy for Crohns: if complications or medically refractory.
Total colectomy for UC: fulminant (uncontrolled bleeding), toxic megacolon, pre-cancerous changes detected or inability to taper steroids.
Complications: short bowel syndrome, watery diarrhea/steatorrhea.

Question 15

Mgmt of C diff

Answer 15

Non-severe: oral flagyl
Severe: Vanco 125 mg PO QID. If no progress, vanco 500 mg PO QID x10-14 days. Add flagyl 500 mg q8 if needed.

Urgent surgical eval if severe leukocytosis or elevated lactate 2.2-4.9, peritoneal signs, severe ileus, toxic megacolon.

Question 16

Mgmt of ischemic colitis

Answer 16

Anticoagulation: IV heparin infusion

Operative mgmt: revascularization via thrombectomy, embolectomy, mesenteric bypass/stent +/- resection.