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Fiser ABSITE Review + Decker + TrueLearn > Chapter 36 - Colorectal > Flashcards

Chapter 36 - Colorectal Flashcards

2
Q

Muscular anatomy of colon?

A

Muscularis mucosa, muscularis propria, plica semilunaris (haustra), taenia coli

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3
Q

Vascular supply of transverse colon?

A

2/3: SMA - right and middle colic

1/3: IMA - L. colic

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4
Q

Vascular supply of ascending colon?

A

SMA - ileocolic, right colic arteries

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5
Q

Vascular supply of descending colon?

A

IMA - L. colic

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6
Q

Vascular supply of the rectum?

A

IMA superior

internal iliac inferior

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7
Q

Vascular supply of sigmoid colon?

A

IMA - sigmoid a.

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8
Q

% of blood flow to mucosa/submucosa?

A

80%

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9
Q

What are the watershed areas?

A

Splenic flexure (Griffith’s point)

Rectum (Sudak’s point)

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10
Q

Neuro control of external sphincter?

A

CNS (voluntary); inferior rectal branch of internal pudendal n, perineal branch (S4)

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11
Q

What muscle makes up the internal sphincter?

A

Continuation of circular bands of the colon muscle

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12
Q

Measurement from anal verge to anal canal?

A

0-5cm

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13
Q

Measurement from anal verge to rectum?

A

5-15cm

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14
Q

Measurement from anal verge to rectosigmoid junction?

A

15-18cm

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15
Q

Transition point between anal canal and rectum?

A

Levator ani

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16
Q

Main nutrients of colonocytes?

A

Short chain fatty acids (butyrate) - produced by microbial breakdown of dietary starches

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17
Q

Prophylaxis for stump pouchitis?

A

Probiotics - VSL 3

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18
Q

Treatment for infectious pouchitis?

A

ciprofloxacin or flagyl

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19
Q

What is lymphocytic colitis? How do you dx and manage it?

A
  • Pth: multifactorial, immune response
  • Psx: pain w/ chronic, water diarrhea in a 65 F
  • Dx: stool cxs, colonoscopy w/ biopsy
  • Tx: avoid NSAID, antidiarrheals, budesonide
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20
Q

What is the name of the anterior, rectovesicular/rectovaginal fascia?

A

Denonvillier’s

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21
Q

What is the name of the posterior, rectosacral fascia?

A

Waldeyer’s

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22
Q

What are the characteristics of polyps associated with increased cancer risk?

A

>2cm, sessile, villous

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23
Q

What are the screening guidelines for patients with FAP?

A

Starting at 10-12y, annual sigmoidoscopy

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24
Q

What are the screening guidelines for patients with attenuated adenomatous polyposis coli?

A

Starting in late teens, annual colonoscopy

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25
Q

What are the screening guidelines for patients with HNPCC?

A

Starting at 20-25y, biennial colonoscopy

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26
Q

What is the treatment when polypectomy shows T1 lesion?

A

Polypectomy only if 2mm margins, well-differentiated, no vascular involvement; otherwise segmental resection

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27
Q

What is the treatment for extensive low rectal villous adenomas with atypia?

A

Transanal excision (with or without mucosectomy); APR only if cancer is present

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28
Q

What is the treatment for T2 lesion after transanal excision of polyp?

A

APR or LAR

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29
Q

What will cause a false-positive guaiac?

A

Beef, Vit C, iron, antacids, cimetidine

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30
Q

Colonoscopy contraindications?

A

Recent MI, splenomegaly, pregnancy if fluoroscopy planned

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31
Q

What is the 2nd leading cause of cancer death?

A

Colorectal cancer

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32
Q

Main gene mutations in colon ca?

A

APC, DCC, p53, k-ras

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33
Q

Most common site of primary colorectal cancer?

A

Sigmoid

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34
Q

Poor prognostic factors for primary colorectal cancer?

A
  • <40 yrs
  • symptomatic patients
  • obstruction
  • perforation
  • rectosigmoid/rectal location
  • ulcerative tumor
  • blood vessel/lymphatic/perineural invasion
  • aneuploidy
  • elevated CEA prior to resection
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35
Q

5 year survival rate with liver mets?

A

25% if resectable and leaves adequate liver function

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36
Q

5 year survival with lung mets?

A

20%

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37
Q

Route of metastasis of colon cancer?

A

To liver via portal vein, to lung via iliac vein

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38
Q

Route of spine metastasis of rectal cancer?

A

Can go directly to spine via Batson’s plexus

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39
Q

Positive prognostic factor for primary colorectal cancer?

A

Lymphocytic penetration

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40
Q

Goals of resection for colon ca?

A

En bloc resection, adequate (2cm) margins, regional adenectomy

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41
Q

Treatment for rectal cancer with rectal pain?

A

APR

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42
Q

What is the best method of picking up hepatic mets?

A

Intraoperative ultrasound

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43
Q

Margin needed for LAR?

A

2cm from levator ani

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44
Q

Side effects of APR?

A

Impotence and bladder dysfunction

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45
Q

Local recurrence higher with rectal or colon ca?

A

Rectal ca

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46
Q

Advantages of preoperative chemo/XRT in rectal cancer?

A

Produces complete response in some patients with rectal ca; preserves sphincter function in some

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47
Q

Treatment for low rectal T1 lesion?

A

Transanal excision if <4cm, negative margins (1cm), well differentiated, no neurologic or vascular invasion; otherwise LAR or APR

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48
Q

Treatment for low rectal T2 or higher?

A

APR or LAR

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49
Q

Chemo for stage III and IV colon CA (node positive or distant mets)?

A

Post op chemo (III - 5FU, leucovorin, oxaliplatin; IV - 5FU and leucovorin)

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50
Q

Chemotherapy for stage II and III rectal ca?

A

Pre op or post op chemo and XRT (5FU, leucovorin, oxaliplatin)

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51
Q

Chemotherapy for stage IV rectal ca?

A

Chemo and XRT +/- surgery (5FU, leucovorin)

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52
Q

When is postop XRT needed for rectal ca?

A

T3 tumors or positive nodes

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53
Q

Most common site of XRT damage?

A

Rectum; vasculitis, thrombosis, ulcers, strictures

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54
Q

Gene mutation related to FAP?

A

APC gene, chromosome 5

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55
Q

% of FAP syndromes are spontaneous?

A

20%

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56
Q

When do polyps present in FAP?

A

Puberty

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57
Q

Surveillance for FAP?

A

Yearly flex sig starting at 10-12 yrs check for polyps; EGD starting at 25 every 2 years

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58
Q

Treatment for FAP?

A

Total colectomy at age 20; proctocolectomy, rectal mucosectomy and ileoanal pouch

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59
Q

Tumors associated with Gardner’s syndrome?

A

Colon ca, desmoid tumors, osteomas

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60
Q

Gene mutation associated with Gardner’s syndrome?

A

APC gene

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61
Q

Tumors associated with Turcot’s syndrome?

A

Colon ca, brain tumors

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62
Q

Gene mutation associated with Turcot’s syndrome?

A

APC gene

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63
Q

Lynch syndrome inheritance?

A

Autosomal dominant

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64
Q

Gene mutation assocaited with Lynch syndrome?

A

DNA mismatch repair (MMR) gene

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65
Q

Lynch I has increased risk of what?

A

Colon cancer

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66
Q

Lynch II has increased risk of what?

A

Colon cancer, ovarian, endometrial, bladder, stomach cancer

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67
Q

What is the Amsterdam criteria?

A

Used to diagnose Lynch syndrome

  • 3 first degree relatives
  • 2 generation penetrance
  • 1 relative w/ cancer < 50
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68
Q

Screening for Lynch syndrome?

A

Colonoscopy at 25 or 10y before primary relative got cancer q1-2 yrs; women need endometrial biopsy Q3y and annual pelvic exams, earlier mammograms

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69
Q

% of Lynch syndrome with metachronous lesions?

A

50%

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70
Q

Tumors associated with juvenile polyposis?

A

Hamartomatous polyps

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71
Q

Surveillance for juvenile polyposis?

A
  • DRE to help dx, colonoscopy after dx
    • polyposis is >5 polyps
  • Yearly: PE, CBC, colonoscopy, EGD starting 12 yr
  • Total colectomy if cancer develops
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72
Q

Cancer risk with juvenile polyposis?

A

Polyps do not have malignant potential, put patients have increased cancer risk - 68% by 60.

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73
Q

Characteristics associated with Peutz-Jeghers syndrome?

A

GI hamartoma polyposis, dark pigmentation around mucous membranes

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74
Q

Surgical options for Peutz-Jeghers?

A

Need polypectomy if possible (may be too many to resect) - 2% colon, duodenal cancer risk

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75
Q

Other cancers associated with Peutz-Jeghers?

A

Gonadal, breast, biliary

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76
Q

Characteristics associated with Cronkhite-Canada syndrome?

A

Hamartomatous polyps, atrophy of nails and hair, hypopigmentation

77
Q

Malignant potential with Cronkhite-Canada syndrome?

A

NO malignant potential

78
Q

Diet associated with sigmoid volvulus?

A

High-fiber (Iran, Iraq)

79
Q

Radiographic findings with sigmoid volvulus?

A

Bent inner tube sign, bird’s beak on gastrografin enema

80
Q

Treatment for sigmoid volvulus?

A

Decompress with colonoscopy (not if having peritoneal signs), bowel prep, sigmoid colectomy on same admission

81
Q

% of sigmoid volvulus that will decompress with colonoscopy?

A

80% reduce, 50% recur

82
Q

Age range for cecal volvulus?

A

20-30y

83
Q

% of cecal volvulus that will decompress with colonoscopy?

A

20%

84
Q

Treatment for cecal volvulus?

A

OR for R. hemi; can try cecopexy if colon is viable and pt is frail

85
Q

Symptoms of ulcerative colitis?

A

Bloody diarrhea, abdominal pain, fever, weight loss

86
Q

Layers of colon involved in ulcerative colitis?

A

Mucosa, submucosa

87
Q

Location of UC?

A

Colon only with rare backwash ilitis

88
Q

Anatomic distribution of UC?

A

Continguous involvement begining distally, spares anus (unlike Crohn’s)

89
Q

Rectal involvement in UC?

A

90%

90
Q

Endoscopic features of UC?

A

Contiguous mucosal involvement, rectal involvement, mucosal friabilitiy, distorted vascular pattern

91
Q

Findings on barium enema of UC?

A

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

92
Q

Medical treatment of UC?

A

Sulfasalazine, 5-ASA, steroids, methotrexate, azathioprine, infliximab, loperamide

93
Q

Clinical diagnosis of toxic megacolon?

A

Fever, tachycardia, dilated colon on abd xray

94
Q

Treatment of toxic megacolon?

A

NGT, fluids, steroids, bowel rest, TPN, abx (treat 50%), then surgery

95
Q

Pathologic features of Crohn’s disease?

A

Transmural inflammation, granulomas, fissures, sumbucosal thickening/fibrosis, submucosal inflammation

96
Q

Distinguishing characteristics of Crohn’s colitis?

A

Small bowel involvement, asymmetric distribution, rectal sparing common, gross bleeding in 70-75%, fistulization, granulomas

97
Q

Endoscopic features of Crohn’s disease?

A

Discontinuous mucosal involvement, aphthous ulcers, relatively normal surrounding mucosa, longitudinal ulcers, cobblestoning, vascular pattern normal

98
Q

Perforation occurs where in UC?

A

Transverse colon

99
Q

Perforation occurs where in Crohn’s?

A

Distal ileum

100
Q

Surgical indications for UC/Crohn’s?

A

Hemorrhage, toxic megacolon, acute fulminant UC, obstruction, dsplasia, cancer, intractability, failure to thrive, long-standing disease, prophylaxis against colon CA

101
Q

Cancer risk for UC/Crohn’s?

A

1-2% per year starting 10y after initial diagnosis

102
Q

Surveilance for UC/Crohn’s?

A

Annual colonoscopy 8-10y after diagnosis

103
Q

Most common extraintestinal manifestation of UC in children requiring total colectomy?

A

Failure to thrive

104
Q

Extraintestinal manifestations of UC that DO NOT get better with colectomy?

A

PSC, ankylosing spondylitis

105
Q

Extraintestinal manifestations of UC that get better with colectomy?

A

Most ocular problems, arthritis, anemia

106
Q

HLA associated with sacroiliitis and ankylosing spondylitis?

A

HLA B27

107
Q

Treatment for pyoderma gangrenosum?

A

Steroids

108
Q

% of carcinoids found in colon and rectum?

A

15% of all carcinoids

109
Q

Treatment for low rectal carcinoids <2cm?

A

WLE with negative margins

110
Q

Treatment for low rectal carcinoids >2cm or invasion of muscularis propria?

A

APR

111
Q

Treatment for colon or high rectal carcinoids?

A

Formal resection with adenectomy

112
Q

What is the Law of LaPlace?

A

Tension = Pressure x Diameter

113
Q

Where is colon perforation with obstruction most likely to occur?

A

Cecum

114
Q

Causes of colonic obstruction?

A

1 Cancer, #2 diverticulitis

115
Q

What is pneumatosis intestinalis?

A

Air in the bowel wall

associated iwth ischemia and dissection of air through areas of bowel wall injury

can be benign, such as w/ COPD

116
Q

What does air in the portal system indicate?

A

Significant infection or necrosis of the large or small bowel

117
Q

Treatment for Ogilvie’s syndrome (pseudoobstruction of colon)?

A

Check electrolytes, discontinue drugs that slow the gut; neostigmine; colonoscopy with decompression; cecostomy

118
Q

% that are carriers for Entameoba histolytica?

A

10%, from contaminated food and water with feces that contain cysts

119
Q

Where does the primary infection occur in amoebic colitis?

A

Colon

120
Q

Where does the secondary infection occur in amoebic colitis?

A

Liver

121
Q

Risk factors for amoebic colitis?

A

Travel to Mexico, EtOH, fecal oral transmission

122
Q

Symptoms of amoebic colitis?

A

Similar to UC (dysentery); chronic form more common with 3-4 BM/day, cramping, fever

123
Q

Diagnosis of amoebic colitis?

A

Endoscopy: ulceration, trophozoites

antiamebic antibodies

124
Q

Treatment for amoebic colitis?

A

Flagyl, diiodohydroxyquin

125
Q

Presentation of actinomyces?

A

Mass, abscess, fistula, induration; suppurative and granulomatous

126
Q

Most common location of actinomyces?

A

Cecum

127
Q

Treatment for actinomyces

A

Tetracycline or penicillin, drainage

128
Q

Treatment for lymphogranuloma venereum?

A

Doxycycline, hydrocortisone

129
Q

Presentation of lymphogranuloma venereum?

A

Proctitis, tenesmus, bleeding; may produce fistulas

130
Q

What causes diverticula?

A

Straining. Herniation of mucosa through the colon wall at sites where areteries enter the muscular wall; thickening of curcular muscle adjacent to diverticulum with luminal narrowing

131
Q

Where do most diverticula occur?

A

L. side (80%) in sigmoid

132
Q

Bleeding is more common with diverticula on which side of the colon?

A

Right

133
Q

Diverticula present in what % of the population?

A

35%

134
Q

How long can a stool guaiac stay positive after a bleed?

A

3 weeks

135
Q

Where is the bleeding from in hematemeis?

A

Pharynx to ligament of Treitz

136
Q

How much blood do you need to make melena?

A

50cc

137
Q

What causes azotemia after GI bleed?

A

Production of urea from bacterial action on intraluminal blood (inc. BUN, total bilirubin)

138
Q

Arteriography will detect bleeding at what rate?

A

>0.5ml/min

139
Q

Tagged RBC scan will detect bleeding at what rate?

A

>0.1ml/min

not adequate to localize bleeding

140
Q

What causes diverticulitis?

A

Perforations in the mucosa in the diverticulum with adjacent fecal contamination

141
Q

% of patients that will have a complication of diverticulitis?

A

25%, most commonly abscess formation

142
Q

Signs of complications of diverticulitis?

A

Obstruction symptoms, fluctuant mass, peritoneal signs, temp >39, WBCs >20

143
Q

Treatment of uncomplicated diverticulitis?

A

Flagys, bactrim, bowel rest for 3-4 days

144
Q

Indications for surgery for diverticulitis?

A

Recurrent disease, emergent complications, inability to exclude cancer

145
Q

Characteristics of colovesicular fistula?

A

Fecaluria, pneumonuria; more common in men

146
Q

Treatment for colovesicular fistula?

A

Close bladder opening, resect involved segment of colon, reanastamosis, diverting ileostomy

147
Q

Most common cause of lower GI bleeding?

A

Diverticulosis

148
Q

% of diverticular bleeding that stops? Recurs?

A

75%, 25%

149
Q

Cause of bleeding from diverticulosis?

A

Disrupted vasa rectum, creates arterial bleeding

150
Q

Diagnosis of diverticular bleeding?

A
  1. Colonoscopy - therapeutic and will localize bleeding
  2. Arteriogram - therapeutic and will localize bleeding
  3. TRBC - sensitive, but cannot localize
151
Q

When is surgery necessary for diverticular bleeding?

A

If recurrent bleeding episodes, and bleeding is localized, segmental resection can be offered.

If hypotensive and not responding to resuscitation, and source not localized, do subtotal colectomy w/ end ileostomy.

152
Q

Characteristics of angiodysplasia colon bleeding in comparison to diverticular bleeding?

A

Usually less severe than diverticular bleeds but more likely to recur (80%)

153
Q

Soft signs of colonic angiodysplasia on angiogram?

A

Tufts, slow emptying

154
Q

Associated cardiac anomaly with colonic angiodysplasia?

A

Aortic stenosis in 20-30%

155
Q

Causes of ischemic colitis?

A

Low-flow state, ligation of IMA at surgery, embolus or thormbus of IMA, sepsis and MI

156
Q

How is the diagnosis of ischemic colitis made?

A

Made by endoscopy: cyanotic edematous mucosa covered with exudates; lower 2/3 rectum spared (supplied by middle and inferior rectal artery from internal iliac and internal pudendal arteries)

157
Q

Symptoms of pseudomembranous colitis?

A

Watery, green, mucoid diarrhea; pain and cramping

158
Q

Key finding of pseudomembranous colitis?

A

PMN inflammation of mucosa and submucosa; pseudomembranes, plaques, ringlike lesions

159
Q

Most common location of pseudomembranous colitis?

A

Distal colon

160
Q

How is the diagnosis of pseudomembranous colitis made?

A

Fecal leukocytes, stool cultures of C. dif/toxin

161
Q

Treatment of pseudomembranous colitis?

A

IV flagyl, PO vanco or flagyl; lactobacillus

162
Q

When does neutropenic typhlitis (enterocolitis) occur?

A

Following chemo when WBCs are low

163
Q

Radiographic finding of neutropenic typhlitis?

A

Pneumoatosis on plain film

164
Q

Treatment of neutropenic typhlitis?

A

Abx; pts will improve when WBC increase

165
Q

How does TB enteritis present?

A

Like Crohn’s disease (stenosise)

166
Q

Treatment of TB enteritis?

A

INH, rifampin; surgery with obstruction

167
Q

What pathology cab Yersinia present like?

A

Mimics appendicitis

168
Q

Treatment of Yersinia?

A

Bactrim or tetracyclin

169
Q

Causes of megacolon?

A
  • IBD
  • C-diff
  • Hirschsprung’s disease
  • Trypanosoma cruzi (most common acquired cause, secondary to destruction of nerves
170
Q

What muscle makes up the external anal sphincter?

A

Puborectalis - continuous with but separate than levator ani

171
Q

What is the function of the colon?

A

recycle nutrients - depends on the metabolic activity of the flora, motility, mucosal absorption and secretion

172
Q

What is the function of the rectum?

A

elimination of stool - dehydration of colonic contents, defection

173
Q

What does the colon absorb?

A

water (passive), sodium (active), bile acids (passive)

bacteria produces SCFAs that drive the active Na absorbption, so if flora is wiped out (BS ABX), then less Na and H2O is absorbed, then diarrhea is caused

174
Q

What does the colon secrete?

A

K - colitis can increase K secretion

Cl - CF and diarrhea inc secretion

175
Q

What is the definition of diarrhea?

A

3 loose stools in one day

176
Q

What is the definition of constipation?

A

fewer than 3 stools in a week

177
Q

What does an preop albumin <3.5 mean for a patient undergoing colorectal surgery?

A

risk factor for anastomotic leak after surgery; delay surgery if possible until nutritionally replete

178
Q

What contamination level is an elective colorectal procedure classified as? What does this imply?

A

clean-contaminated: abx ppx 30 min before incision and redosed every 4 hrs

2nd or 3rd gen cephalosporin vs fluoroquinolone/flagyl vs fluoroquinolone/clindamycin vs ertapenem

179
Q

Characteristics of transverse loop colostomy

A
  • usually used to divert from distal obstruction
  • liquid, foul-smelling effluent
  • higher risk of prolapse
  • only temporary complete diversion
180
Q

What are the key elements in the enhanced recovery pathway for colorectal surgery?

A
  • appropriate patient selsection
  • MIS
  • periop fluid mgmt
  • early feeding
  • early ambulation
  • multimodal pain control
  • outcomes: decreased primary length of stay, total hospital stay, fewer complications
181
Q

Do colorectal surgery patients require an NGT after every surgery? Do you have to wait for return of bowel fct before feeding?

(ERAS protocol)

A

no - w/o ngt, pts have early ROBF, fewer complications, and dec length of stay

no - early feeding decreases postop complications and length of stay w/o affecting dehiscence rate or increasing pneumonias or vomiting episodes

182
Q

Treat a cecocolic volvulus

A

Right colectomy

183
Q

After treatment of uncomplicated diverticulitis, when should colonoscopy be performed?

A

4-6 weeks - exclude neoplasm or other colonic disease (IBD)

184
Q

What is the most common distal site of diverticular fistula? Diagnose and treat it.

A

Dome of the bladder (vagina, small bowel, skin are other notable sites)

DX: CT w/ air in the bladder in setting of diverticulitis

Tx: BS Abx initially; colonoscopy to r/o cancer and IBD; elective resection of colon and tract w/ primary anastomosis, dmg to bladder can be repaired primarily w/ Foley drainage for 7 days

185
Q

What is the most likely location for a colonic volvulus?

A

sigmoid colon - 2/3 of all cases of colonic volvulus

permitted by elongated bowel w/ lengthy mesentary and narrow parietal attachment

pts: old, chronic constipation, neuropsych conditions on psychotropic drugs

186
Q

Treat a sigmoid volvulus (same as transverse volvulus)

A
  • assure no need for ex-lap Hartmann: HDS and no peritonitis
  • resuscitate
  • decompress with rectal tube through rigid proctoscope or flex sig
  • confirm w/ radiograph
  • leave tube in place for 1-2 days
  • completion colonoscopy to exclude cancer
  • elective sigmoid resection w/ primary anastomosis

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