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Flashcards in chapter 36: colorectal Deck (266):
1

Colon secretes ____ and reabsorbs _____

colon secretes K and reabsorbs Na and water (mostly in right colon and cecum)

2

4 layers of the colon

mucosa (columnar epithelium) -> submucosa -> muscularis propria -> serosa

3

colonic layer: small interwoven inner muscle layer just below mucosa but above basement membrane

muscularis mucosa

4

colonic layer: circular layer of muscle

muscularis propria

5

retroperitoneal portions of colon

ascending, descending and sigmoid colon are all retroperitoneal
- peritoneum covers anterior upper and middle 1/3 of the rectum

6

transverse bands that form haustra

plicae semiliunares

7

3 bands that run longitudinally along colon. at rectosigmoid junction, these become broad and completely encircle the bowel

taenia coli

8

cm: dentate line from anal verge

2cm

9

cm: anal transition zone from anal verge

4 cm

10

vasculature: ascending and 2/3 of transverse colon

SMA (ileocolic, right and middle colic arteries)

11

vasculature: 1/3 transverse, descending colon, sigmoid colon, and upper portion of the rectum

IMA (left colic, sigmoid branches, superior rectal artery)

12

vascular: runs along colon margin, connecting SMA to IMA (provides collateral flow)

marginal artery

13

artery: short direct connection between SMA and IMA

Arc of Riolan

14

how is vascular supply distributed in the colon?

80% of blood flow goes to mucosa and submucosa

15

venous drainage of colon?

follows arterial except IMV, which goes to the splenic vein

16

what forms the portal vein?

splenic vein joins the SMV to form the portal vein behind the pancreas

17

what does superior rectal artery branch off of?

superior rectal artery - branch of IMA

18

what is the middle rectal artery a branch of?

branch of internal iliac

19

what contains the middle rectal arteries during low anterior resection [LAR] or abdominoperineal resection [APR]?

the lateral stalks

20

what is the inferior rectal artery a branch of?

branch of internal pudendal (which is a branch of the internal iliac).

21

where do superior and middle rectal veins drain?

superior and middle rectal veins drain into the IMV and eventually the portal vein.

22

where do inferior rectal veins drain?

inferior rectal veins drain into the internal iliac veins and eventually the caval system

23

major blood supply of the colon

SMA and IMA

24

drain to IMA nodal lymphatics

superior and middle rectum

25

drains primarily to IMA nodes, also to internal iliac nodes

lower rectum

26

does the bowel wall contain lymphatics?

bowel wall contains mucosal and submucosal lymphatics.

27

what are the watershed areas in the colon?

- splenic flexure (Griffith's point)
- rectum (Sudak's point)

28

watershed area: SMA and IMA junction

splenic flexure (Griffith's point)

29

watershed area: superior rectal and middle rectal junction

rectum (sudak's point)

30

more sensitive to ischemia: colon vs small bowel

colon more sensitive to ischemia than small bowel secondary to decreased collaterals

31

sphincter: is the continuation of the levator ani muscle (striated muscle)
- nerve: inferior rectal branch of internal pudendal nerve

external sphincter (puborectalis muscle) - under CNS (voluntary) control

32

- involuntary control
- is the continuation of the muscularis propria (smooth muscle)
- is normally contracted

internal sphincter

33

inner nerve plexus

meissner's plexus

34

outer nerve plexus

auerbach's plexus

35

parasympathetic to colon

pelvic splanchnic nerves

36

sympathetics to colon

lumbar and sacral plexus

37

from anal verge: anal canal

0 - 5 cm

38

from anal verge: rectum

5 - 15 cm

39

from anal verge: rectosigmoid junction

15 - 18 cm

40

marks the transition between anal canal and rectum

levator ani

41

mucus-secreting goblet cells

crypts of lieberkuhn

42

slow transit time; patients may need subtotal colectomy

colonic inertia

43

main nutrient of colonocytes

short-chain fatty acids

44

tx: stump pouchitis (diversion or disuse proctitis)

short-chain fatty acids

45

tx: infectious pouchitis

metronidazole (flagyl)

46

rectovesicular fascia in men; rectovaginal fascia in women

denonvilliers fascia (anterior)

47

rectosacral fascia

waldeyer's fascia (posterior)

48

most common polyp; no cancer risk

hyperplastic polyps

49

most common (75%) intestinal neoplastic polyp (these are generally pedunculated)

tubular adenoma

50

polyp most likely to produce symptoms
- these are generally sessile and larger than tubular adenomas

villous adenoma

51

villous adenomas: percent that have cancer

50% of villous adenomas have cancer

52

polyps: characteristics of lesions with increased cancer risk

> 2cm
sessile
villous

53

polyps have ___ side predominance

polyps have left side predominance

54

what type of polyps can be removed endoscopically?

most pedunculated polyps can be removed endoscopically

55

management: if not able to get all of the polyp endoscopically (which usually occurs with sessile polyps)

need segmental resection

56

when is polypectomy adequate treatment for invasive carcinoma?

only if the margin is sufficient (2mm), the carcinoma is not poorly differentiated, and no evidence of venous or lymphatic invasion is found.

57

polyps: basement membrane is intact (carcinoma in situ)

high-grade dysplasia

58

what is carcinoma in situ?

malignant cells are confined to the mucosa

59

polyps: into muscularis mucosa (CIS -> still has not gone thru the basement membrane)

intramucosal cancer

60

polyps: into submucosa (T1)

invasive cancer

61

colon cancer screening recommendations

at 50 for normal risk, at 40 (or 10 years before youngest case) for intermediate risk (e.g. family history of colon CA)

62

colon cancer screening options

1) colonoscopy q 10 years - or -
2) high-sensitivity FOBT q3 AND flex sig q5yrs - or -
3) high-sensitivity FOBT annually

Possible option: double contrast barium enema or CT colonography

63

what can cause a false-positive guaiac?

beef, vitamin C, iron, cimetidine

64

when do you not want to do colonoscopy?

recent MI, splenomegaly, pregnancy (if fluoroscopy planned)

65

management: polypectomy shows T1 lesion

polypectomy is adequate if margins are clear (2mm), is well differentiated, and has no vascular / lymphatic invasion; otherwise, need formal colon resection

66

tx: extensive low rectal villous adenomas with atypia

transanal excision (can try mucosectomy) as much of the polyp as possible.
- NO APR unless cancer is present.

67

management: pathology shows T1 lesion after transanal excision of rectal polyp

transanal excision is adequate if margins are clear (2mm), it is well differentiated, and it has no vascular / lymphatic invasion

68

tx: pathology shows T2 lesion after transanal excision of rectal polyp

patient needs APR or LAR

69

2nd leading cause of CA death

colorectal cancer

70

symptoms of colorectal cancer

anemia, constipation, and bleeding

71

why are red meat and fat associated with colorectal cancer?

O2 radicals are thought to have a role

72

what infection is associated with colorectal cancer?

clostridium septicum infection

73

main gene mutations in colorectal cancer

APC, DCC, p53, and k-ras

74

most common site of primary colorectal cancer

sigmoid colon

75

most important prognostic factor for colorectal cancer

nodal status
- spreads to nodes first

76

primary sites of metastases in colorectal cancer

#1 liver
#2 lung

77

how does colorectal cancer metastasize to liver?

portal vein

78

how does colorectal cancer metastasize to lung?

iliac vein

79

5 year survival rate for colorectal cancer with liver metastases

if resectable and leaves adequate liver function, patients have 35% 5-year survival (5-YS) rate

80

5 year survival rate for colorectal cancer with lung metastases

25% 5-YS rate in selected patients after resection

81

management: isolated liver or lung metastases in colorectal cancer

isolated liver or lung mets should be resected

82

rate of patients with drop metastases to ovaries in colorectal cancer

5%

83

why can rectal CA metastasize to spine directly?

via Batson's plexus (venous)

84

does colon CA go to bone?

colon CA typically does not go to bone

85

surgery: colorectal CA growing into adjacent organs

can be resected en bloc with a portion of the adjacent organ (i.e., partial bladder resection)

86

colorectal ca prognosis: lymphocytic penetration

patients have an improved pronosis

87

colorectal ca prognosis: mucoepidermoid

worst prognosis

88

colorectal ca: good at assessing depth of invasion (sphincter involvement), recurrence, and presence of enlarged nodes

rectal ultrasound

89

mandatory in diagnosis of colorectal ca

need total colonoscopy to rule out synchronous lesions in patients with colorectal CA

90

colorectal ca: goals of resection

en bloc resection, adequate adenectomy

91

management of most right-sided colon CAs

can be treated with primary anastomosis without ostomy

92

management of rectal pain with rectal ca

patient needs APR

93

margins for colorectal cancer surgery

generally need 2-cm margins

94

colorectal ca: best method of picking up intrahepatic metastases

intraoperative ultrasound (U/S)

95

intraoperative ultraound
- resolution: conventional U/S

10 mm

96

intraoperative ultraound
- resolution: abdominal CT

5-10mm

97

intraoperative ultraound
- resolution: abdominal MRI

5-10mm (better resolution than CT)

98

intraoperative ultraound
- resolution: intraoperative U/S

3-5mm

99

permanent colostomy; anal canal is excised along with the rectum

abdominoperineal resection (APR)

100

potential complications of abdominoperineal resection (APR)

can have impotence and bladder dysfunction (injured pudendal nerves)

101

when is abdominoperineal resection indicated?

indicated for malignant lesions only (not benign tumors) that are not amenable to LAR

102

margins for abdominoperineal resection (APR)

need at least a 2-cm margin (2cm from levator ani muscles) for LAR, otherwise will need APR

103

risk of local recurrence: rectal CA vs colon CA

risk of local recurrence higher with rectal CA than with colon CA in general

104

produces complete response in some patients with rectal CA; preserves sphincter function in some

preoperative chemo-XRT

105

T? - into submucosa

T1

106

T? - into muscularis propria

T2

107

T? - into serosa or thru muscularis propria if no serosa is present

T3

108

T? - through serosa into free peritoneal cavity or into adjacent organs / structures if no serosa is present

T4

109

N? - nodes negative

N0

110

N? - 1-3 nodes positive

N1

111

N? - >/ 4 nodes positive

N2

112

N? - central nodes positive

N3

113

M? - distant metastases

M1

114

tx: low rectal T1 (limited to submucosa)

can be excised transanally if

115

tx: low rectal T2 or higher

APR or LAR

116

chemotherapy: stage 3 and 4 colon ca (nodes positive or distant metastases)

postop chemo, no XRT

117

chemotherapy: stage 2 and 3 rectal ca

pre-op chemo-XRT

118

chemotherapy: stage 4 and rectal CA

chemo and XRT +/ surgery (possibly just colostomy, may want to avoid APR in patients with metastatic disease)

119

colorectal CA: chemo regimen

5FU, leucovorin, and oxaliplatin (FOLFOX)

120

colorectal CA: benefits XRT

decreases local recurrence and increases survival when combined with chemotherapy

121

colorectal CA: XRT damage

rectum most common site of injury -> vasculitis, thrombosis, ulcers, strictures

122

colorectal CA: pre-op chemo XRT

may help shrink rectal tumors, allowing down-staging of the tumor and possibly allowing LAR versus APR

123

colorectal CA: rate of recurrence

20% have a recurrence (usually occurs within 1 year)
- 5% get another primary -> main reason for surveillance colonoscopy

124

why does colorectal ca require surveillance?

5% get another primary -> main reason for surveillance colonoscopy. follow up colonoscopy at 1 year -> mainly to check for new primary colon CA (metachronous)

125

autosomal dominant; all have cancer by age 40

familial adenomatous polyposis (FAP)

126

gene involved in FAP

APC gene - chromosome 5

127

how many FAP syndromes are spontaneous?

20% of FAP syndromes are spontaneous

128

when do FAP syndromes present?

polyps not present at birth; are present in puberty

129

do you need colonoscopy surveillance in FAP?

do not need colonoscopy for surveillance in patients with suspected FAP -> just need flexible sigmoidoscopy to check for polyps

130

management of FAP

all need total colectomy prophylactically at age 20

131

why do you need to check the duodenum every 2 years in FAP?

also get duodenal polyps

132

FAP surgery

proctocolectomy, rectal mucosectomy, and ileoanal pouch (J-puch)
- need lifetime surveillance of residual rectal mucosa
- total proctoceolectomy with end ileostomy is also an option

133

MCC death in FAP patients following colectomy

periambpullary tumors of the duodenum

134

patients get colon CA (associated with APC gene) and desmoid tumors / osteomas

Gardner's syndrome

135

patients get colon CA (associated with APC gene) and brain tumors

Turcot's syndrome

136

5% of the population, autosomal dominant
- associated with DNA mismatch repair gene
- predilection for right-sided and multiple cancers

Lynch syndromes (hereditary nonpolyposis colon cancer)

137

Lynch syndrome: just colon CA risk

Lynch 1

138

Lynch syndrome: patients also have increased risk of ovarian, endometrial, bladder, and stomach cancer

Lynch 2

139

Amsterdam criteria for Lynch syndrome

"3,2,1" -> at least 3 first degree relatives, over 2 generations, 1 with cancer before age 50

140

surveillance for lynch syndrome

need surveillance colonoscopy starting at age 25 or 10 years before primary relative got cancer (also need surveillance program for the other CA types in the family)

141

rate of metachronous lesions in lynch syndrome

50% get metachronous lesions within 10 years; often have multiple primaries

142

surgery for lynch syndrome

need total proctocolectomy with first cancer operation

143

- more common with high-fiber diets (Iran, Iraq)
- occurs in debilitated psychiatric patients, neurologic dysfunction, laxative abuse
- symptoms: pain, distention, and obstipation

sigmoid volvulus

144

what type of obstruction is sigmoid volvulus?

causes closed-loop obstruction -> sigmoid colon twists on itself

145

abdominal Xr: sigmoid volvulus

bent inner tube sign; gastrograffin enema may show bird's beak sing (tapered colon)

146

management of gangrenous bowel in sigmoid volvulus

do not attempt decompression with gangrenous bowel or peritoneal signs -> go to OR for sigmoidectomy

147

tx: sigmoid volvulus

decompress with colonoscopy (80% reduce, 50% will recur), give bowel prep, and perform sigmoid colectomy during same admission

148

less common than sigmoid volvulus; occurs in 20s-30s
- can appear as SBO with dilated cecum in the RLQ

cecal volvulus

149

role of colonoscopy in cecal volvulus

can try to decompress with colonoscopy but unlikely to succeed (only 20%)

150

OR treatment for cecal volvulus

Right hemicolectomy probably best treatment; can try cecoplexy if colon is viable and patient is frail

151

bloody diarrhea, abdominal pain, fever and weight loss
- involves the mucosa and submucosa
- strictures and fistulae unusual

ulcerative colitis

152

IBD: spares anus

ulcerative colitis (unlike crown's)
- usually starts distally in rectum and is contiguous (no skip areas like crohn's)

153

IBD: universal bleeding and mucosal friability with pseudo polyps and collar button ulcers

ulcerative colitis

154

what do you need to rule out in ulcerative colitis?

always need to rule out infectious etiology

155

ulcerative colitis: when can backwash ileitis occur?

backwash ileitis can occur with proximal disease

156

characteristics of barium enema in chronic ulcerative colitis

loss of haustra, narrow caliber, short colon, and loss of redundancy

157

medical treatment: ulcerative colitis

sulfasalazine (or 5-ASA) and loperamide for maintenance therapy
- steroids for acute flares

158

ulcerative colitis: medical treatment that can maintain remission

5-ASA and sulfasalazine

159

ulcerative colitis: medical treatment for steroid-resistant disease

consider cyclosporine or infliximab

160

ulcerative colitis: > 6 bloody stools/d, fever, increased HR, drop in hemoglobin, leukocytosis

toxic colitis

161

ulcerative colitis: > 6 blood stools/d, fever, increased heart rate, drop in hemoglobin, leukocytosis, distention, abdominal pain and tenderness

toxic megacolon

162

toxic colitis and toxic megacolon: initial treatment

NGT, fluids, steroids, bowel rest, and antibiotics (ciprofloxacin and Flagyl) will treat 50% adequately; other 50% require surgery
- follow clinical response and abdominal radiography

163

what do you want to avoid in toxic colitis and toxic megacolon?

avoid barium enemas, narcotics, anti-diarrheal agents, and anti-cholinergics

164

absolute indications for surgery with toxic colitis and toxic megacolon

pneumoperitoneum, diffuse peritonitis, localized peritonitis with increasing abdominal pain and/or colonic distention > 10 cm, uncontrolled sepsis, major hemorrhage

165

relative indications for surgery with toxic colitis and toxic megacolon

inability to promptly control sepsis, increasing megacolon, failure to improve within 24-48 hr, increasing toxicity or other signs of clinical deterioration, continued transfusion requirements

166

more common location of perforation with ulcerative colitis

transverse colon more common

167

more common location of perforation with crohn's disease

distal ileum most common

168

surgical indications for ulcerative colitis

massive hemorrhage, refractory toxic megacolon, acute fulminant ulcerative colitis (occurs in 15%), obstruction, any dysplasia, cancer, intractability, systemic complications, FTT, and long stranding disease (> 10 years) as prophylaxis against colon CA (Some controversy here)

169

ulcerative colitis: emergent/urgent resection

total proctocolectomy and bring up ileostomy
- perform definitive hook-up later

170

elective resection: ulcerative colitis

ileoanal anastomosis - rectal mucosectomy, J-pouch and ileoanal (low rectal) anastomosis; not used with crohn's disease

171

what does illeoanal anastomosis protect in ulcerative colitis?

can protect bladder and sexual function

172

ulcerative colitis: why do many illeoanal anastomoses need resection?

secondary to cancer, dysplastic changes, refractory pouchitis, or pouch failure (incontinence)
- need temporary diverting ileostomy (6-8 weeks) while pouch heals

173

mc major morbidity in illeoanal anastomosis in ulcerative colitis

can lead to sepsis (Tx: drainage, antibiotics)

174

ulcerative colitis: tx - infectious pouchitis

flagyl

175

two options with elective resections in ulcerative colitis

ileoanal anastomosis and APR with ileostomy

176

cancer risk in ulcerative colitis

1% per year starting 10 years after initial diagnosis for patients with pancolitis
- cancer more evenly distributed throughout colon
- need yearly colonoscopy starting 8-10 years after diagnosis

177

most common extra intestinal manifestation of ulcerative colitis requiring total colectomy

failure to thrive in children

178

ulcerative colitis: do not get better with colectomy

primary sclerosing cholangitis, ankylosing spondylitis

179

ulcerative colitis: get better with colectomy

most ocular problems, arthritis, and anemia

180

ulcerative colitis: 50% get better

pyoderma gangrenosum

181

ulcerative colitis: HLA b27

sacroilitis, ankylosing spondylitis, ulcerative colitis

182

is thromboembolic disease a risk in ulcerative colitis?

yes

183

tx: pyoderma gangrenosum in ulcerative colitis

steroids

184

represents 15% of all carcinoids; infrequent cause of carcinoid syndrome
- metastases related to size of tumor
- 2/3 have either local or systemic spread

carcinoid of the colon and rectum

185

treatment: low rectal carcinoids

wide local excision with negative margins

186

treatment: low rectal carcinoids > 2cm or invasion of muscularis propria

APR

187

tx: colon or high rectal carcinoids

formal resection with adenectomy

188

location: colon perforation with obstruction

most likely to occur in cecum

189

law of laplace

tension = pressure x diameter

190

colonic obstruction: can be worrisome; can have rapid progression and perforation with minimal distention

closed loop-obstruction

191

what can lead to closed-loop obstruction in colonic obstruction?

competent ileocecal valve

192

primary causes of colonic obstruction

#1 cancer
#2 diverticulitis

193

air in the bowel wall, associated with ischemia and dissection of air through areas of bowel wall

pneumatosis intestinalis

194

usually indicates significant infection or necrosis of the large or small bowel; often an ominous sign

air in the portal system

195

pseudo obstruction of colon
- associated with opiate use; bedridden or older patients; recent surgery, infection or trauma
- get a massively dilated colon, which can perforate

ogilvie's syndrome

196

tx: ogilvie's syndrome

check and replace electrolytes (especially K); discontinue drugs that slow the gut (e.g. morphine); NGT

197

high risk of perforation in ogilvie's syndrome

if colon > 10 cm (high risk of perforation) -> decompression with colonoscopy and neostigmine; cecostomy if that fails

198

- from contaminated food and water with feces that contain cysts
- risk factors: travel to Mexico, ETOH; fecal-oral transmission

amoebic colitis: entamoeba histolytica

199

symptoms: similar to ulcerative colitis (dysentery); chronic more common form (3-4 bowel movements/day, cramping, and fever)

amoebic colitis - entamoeba histolytica

200

primary and secondary infection of amoebic colitis

- primary infection - occurs in colon
- secondary infection - occurs in liver

201

dx: amoebic colitis

endoscopy -> ulceration, trophozoites; 90% have anti-amebic antibodies

202

tx: amoebic olitis

flagyl, diiodohydroxyquin

203

can present as a mass, abscess, fistula, or induration; suppurative and granulomatous

actinomyces

204

most common location of actinomyces

cecum most common location; can be confused with CA

205

pathology: actinomyces

yellow-white sulfur granules

206

tx: actinomyces

penicillin or tetracycline, drainage of any abscess

207

herniation of mucosa though the colon wall at sites where arteries enter the muscular wall

diverticula

208

how is adjacent colon affected by diverticula?

circular muscle thickens adjacent to diverticulum with luminal narrowing

209

what causes diverticula?

caused by straining (increased intraluminal pressure)

210

where do most diverticula occur?

most diverticula occur on left side (80%) in the sigmoid colon

211

symptoms: right-sided diveritucula

bleeding is more likely with right-sided diverticula (50% of bleeds occur on right)

212

diverticula: more likely to present on the left side

diverticulitis

213

rate of diverticula in the populations

presents in 35% of the population

214

lower GIB: how long does stool guaic stay positive

for up to 3 weeksn

215

bleeding anywhere near pharynx to ligament of Treitz

hematemsis

216

passage of tarry stools; need as little as 50 cc

melena

217

management of lower gastrointestinal hemorrhage

- rule out UGI: NGT
- r/o rectal source: proctoscopy

218

what causes azotemia after GIB?

caused by production of urea from bacterial action on intraluminal blood (increased BUN; also get elevated total bilirubin)

219

bleeding rate to see arteriography

bleeding must be >/ 0.5 cc/min

220

bleeding rate for tagged RBC scan

bleeding must be >/ 0.1 cc/min

221

denotes infection and inflammation of the colonic wall as well as surrounding tissue
- LLQ pain, tenderness, fever, leukocytosis

diverticulitis

222

what causes diverticulitis

result of mucosal perforations in the diverticulum with adjacent fecal contamination

223

dx: diverticulitis

CT scan is needed only if worried about complications of disease

224

follow-up after episode of diverticulitis

need follow-up colonoscopy after an episode of diverticulitis to rule out colorectal cancer

225

most common complication of diverticulitis

abscess formation; can usually percutaneously drain

226

signs of complications of diverticulitis

obstruction symptoms, fluctuant mass, peritoneal signs, temperature > 39 and WBCs > 20

227

tx: uncomplicated diverticulitis

levofloxacin and Flagyl; bowel rest for 3-4 days (mild cases can be treated as an outpatient)

228

indications for surgery in diverticulitis

for significant complications (total obstruction not resolved with medical therapy, perforation, or abscess formation not amenable to percutaneous drainage) or inability to exclude cancer

229

surgery: diverticulitis

need to resect all of the sigmoid colon down to the superior rectum (distal margin should be normal rectum)

230

80% discovered at time of incision for appendectomy

right-sided diverticulitis
- tx: right hemicolectomy

231

fecaluria, pneumouria
- occurs in men; women are more likely to get colovaginal fistula

colovesicular fistula

232

best diagnostic test for colovesicular fistula

cystoscopy is the best diagnostic test

233

tx: colovesicular fistula

close bladder opening, resect involved segment of colon, and perform reanastomosis, diverting ileostomy; interpose momentum between the bladder and colon

234

MCC of lower GIB

diverticulosis (usually causes significant bleeding)

235

diverticulosis bleeding: ___stops spontaneously; recurs in ___

75% stops spontaneously; recurs in 25%

236

what causes diverticulosis bleeding?

caused by disrupted vasa rectum; creates arterial bleeding

237

dx: diverticulosis bleeding

NG tube to rule out upper GI source
- colonoscopy as a first step -> can be therapeutic (demo-clips best) and can localize bleeding should surgery be required

238

dx: massive bleeding in diverticulosis

angio 1st if massive bleed (hypotension, tachycardia) -> want to localize area for surgery; may be able to treat at angio with highly selective coil embolization

239

dx: diverticulosis bleeding if hypotensive and not responding to resuscitation

go to operative room if hypotensive and not responding to resuscitation -> colectomy at site of bleeding if identity or subtotal colectomy if bleeding source has not been localized

240

dx: diverticulosis bleeding for intermittent bleeds that are hard to localized

tagged RBC scan

241

tx: diverticulosis bleeding

colonoscopy can ligate bleeder
- with arteriography, can use vasopressin (to temporize) or highly selective coil embolization; also demonstrates with the bleed is should surgery be required

242

tx: diverticulosis bleeding that is not localized and not controlled with colonoscopy

may need segmental colectomy or possible subtotal colectomy

243

management of patients with recurrent diverticular bleeds

should have resection of that area

244

- increased on right side of colon
- bleeds are usually less severe than diverticular bleeds but are more likely to recur (80%)
- causes venous bleeding

angiodysplasia bleeding

245

soft signs of angiodysplasia on angiogram

tufts, slow emptying

246

coexisting comorbidity in angiodysplasia

20% of patients with angiodysplasia have aortic stenosis (usually gets better after valve replacement)

247

symptoms: abdominal pain, bright red bleeding

ischemic colitis

248

what can cause ischemic colitis?

can be caused by low-flow state (e.g. recent MI, CHF), ligation of the IMA at surgery (e.g. AAA repair), embolus or thrombosis of the IMA, sepsis

249

most vulnerable colonic sites to low-flow states

splenic flexure and upper rectum

250

point: SMA and IMA junction

Griffith's point (splenic flexure)

251

superior rectal and middle rectal artery junction

sudeck's point

252

dx: ischemic colitis

CT scan or endoscopy -> cyanotic edematous mucosa covered with exudates

253

why is the lower 2/3 of the rectum spared in ischemic colitis?

supplied by the middle and inferior rectal arteries (off internal iliac)

254

ischemic colitis: management of suspected gangrenous colitis (peritonitis)

no colonoscopy and go to OR -> sigmoid resection or let hemicolectomy usual

255

symptoms: watery, green, mucoid diarrhea; pain and cramping
- can occur up to 3 weeks after antibiotics; increased in post op, elderly, and ICU patients
- carrier state not eradicated; 15% recurrence

pseudomembranous colitis (C difficle colitis)

256

key finding: pseudomembranous colitis

PMN inflammation of mucosa and submucosa (pseudomembranes, plaques, and ringlike lesions)

257

most common location of pseudomembranous colitis (C diff)

most common in the distal colon

258

dx: c diff (pseudomembranous colitis)

c diff toxin

259

tx: pseudomembranous colitis (c diff)

oral - vancomycin or flagyl
IV: flagyl
- lactobacillus can also help; stop other antibiotics or change them

260

- follows chemotherapy when WBC are low (nadir)
- can mimic surgical disease
- can often see pneumatosis intestinalis (not a surgical indication)

neutropenic typhlitis (enterocolitis)

261

tx: neutropenic typhlitis (enterocolitis)

antibiotics; patients will improve when WBCs increase ; surgery only for free perforation

262

other causes of colitis

salmonella, shigella, campylobacter, cmv, yersinia (can mimic appendicitis in children), other viral infections, giardia

263

can mimic appendicitis; comes from contained food (Feces/urine)
-tx?

yersinia
- tx: tetracycline or bactrim

264

propensity for volvulus; enlargement is proximal to non-peristalsing bowel

megacolon

265

megacolon - rectosigmoid most common
- dx: rectal biopsy

hirschsprung's disease

266

megacolon: most common acquired cause, secondary to destruction of nerves

trypanosoma cruzi