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 ascending colon?

A

SMA - ileocolic, right colic arteries

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4
Q

Vascular supply of transverse colon?

A

2/3: SMA - right and middle colic, 1/3: IMA - L. colic

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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 and internal iliac

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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

What muscle makes up the external sphincter?

A

Puborectalis, continuation of the levator ani

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11
Q

Neuro control of external sphincter?

A

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

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12
Q

What muscle makes up the internal sphincter?

A

Continuation of circular bands of the colon muscle

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13
Q

Measurement from anal verge to anal canal?

A

0-5cm

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14
Q

Measurement from anal verge to rectum?

A

5-15cm

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15
Q

Measurement from anal verge to rectosigmoid junction?

A

15-18cm

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16
Q

Transition point between anal canal and rectum?

A

Levator ani

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17
Q

Main nutrients of colonocytes?

A

Short chain fatty acids (butyrate)

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18
Q

Treatment for stump pouchitis?

A

Short chain fatty acid enemas

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19
Q

Treatment for infectious pouchitis?

A

Flagyl

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20
Q

Treatment for lymphocytic colitis?

A

Sulfasalazine

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21
Q

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

A

Denonvillier’s

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22
Q

What is the name of the posterior, rectosacral fascia?

A

Waldeyer’s

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23
Q

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

A

> 2cm, sessile, villous

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24
Q

What are the screening guidelines for patients with FAP?

A

Starting at 10-12y, annual sigmoidoscopy

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25
Q

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

A

Starting in late teens, annual colonoscopy

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26
Q

What are the screening guidelines for patients with HNPCC?

A

Starting at 20-25y, biennial colonoscopy

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27
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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28
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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29
Q

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

A

APR or LAR

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30
Q

What will cause a false-positive guaiac?

A

Beef, Vit C, iron, antacids, cimetidine

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31
Q

Colonoscopy contraindications?

A

Recent MI, splenomegaly, pregnancy if fluoroscopy planned

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32
Q

What is the 2nd leading cause of cancer death?

A

Colorectal cancer

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33
Q

Main gene mutations in colon ca?

A

APC, DCC, p53, k-ras

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34
Q

Most common site of primary colorectal cancer?

A

Sigmoid

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35
Q

Poor prognostic factors for primary colorectal cancer?

A

Age <40, symptomatic patients, obstruction & perforation, rectosigmoid/rectal location, ulcerative tumors, blood vessel/lymphatic/perineural invasion, aneuploidy, elevated CEA prior to resection

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36
Q

5 year survival rate with liver mets?

A

25% if resectable and leaves adequate liver function

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37
Q

5 year survival with lung mets?

A

20%

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38
Q

Route of metastasis of colon cancer?

A

To liver via portal vein, to lung via iliac vein

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39
Q

Rout of metastasis of rectal cancer?

A

Can go directly to spine via Batson’s plexus

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40
Q

Positive prognostic factor for primary colorectal cancer?

A

Lymphocytic penetration

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41
Q

Goals of resection for colon ca?

A

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

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42
Q

Treatment for rectal cancer with rectal pain?

A

APR

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43
Q

What is the best method of picking up hepatic mets?

A

Intraoperative ultrasound

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44
Q

Margin needed for LAR?

A

2cm from levator ani

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45
Q

Side effects of APR?

A

Impotence and bladder dysfunction

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46
Q

Local recurrence higher with rectal or colon ca?

A

Rectal ca

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47
Q

Advantages of preoperative chemo/XRT?

A

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

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48
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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49
Q

Treatment for low rectal T2 or higher?

A

APR or LAR

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50
Q

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

A

Post op chemo, no XRT (III - 5FU, leucovorin, oxaliplatin; IV - 5FU and leucovorin)

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51
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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52
Q

Chemotherapy for stage IV rectal ca?

A

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

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53
Q

When is postop XRT needed for rectal ca?

A

T3 tumors or positive nodes

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54
Q

Most common site of XRT damage?

A

Rectum; vasculitis, thrombosis, ulcers, strictures

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55
Q

% of patients that will have recurrence?

A

20% (50% within 6mo, 100% within 3 years)

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56
Q

% that will have another primary?

A

5% (main reason for surveillance colonoscopy)

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57
Q

Gene mutation related to FAP?

A

APC gene, chromosome 5

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58
Q

% of FAP syndromes are spontaneous?

A

20%

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59
Q

When do polyps present in FAP?

A

Puberty

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60
Q

Surveillance for FAP?

A

Flex sig to check for polyps; EGD every 2 years

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61
Q

Treatment for FAP?

A

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

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62
Q

Tumors associated with Gardner’s syndrome?

A

Colon ca, desmoid tumors, osteomas

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63
Q

Gene mutation associated with Gardner’s syndrome?

A

APC gene

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64
Q

Tumors associated with Turcot’s syndrome?

A

Colon ca, brain tumors

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65
Q

Gene mutation associated with Turcot’s syndrome?

A

APC gene

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66
Q

Lynch syndrome inheritance?

A

Autosomal dominant

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67
Q

Gene mutation assocaited with Lynch syndrome?

A

DNA mismatch repair gene

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68
Q

Lynch I has increased risk of what?

A

Colon cancer

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69
Q

Lynch II has increased risk of what?

A

Colon cancer, ovarian, endometrial, bladder, stomach cancer

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70
Q

What is the Amsterdam criteria?

A

3-2-1; 3 first degree relatives, over 2 generations, 1 with cancer before age 50

71
Q

Surveillance for Lynch syndrome?

A

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

72
Q

% of Lynch syndrome with metachronous lesions?

A

50%

73
Q

Tumors associated with juvenile polyposis?

A

Hamartomatous polyps

74
Q

Surveillance for juvenile polyposis?

A

Colonic surveillance, total colectomy if cancer develops

75
Q

Cancer risk with juvenile polyposis?

A

Polyps do not have malignant potential, put patients have increased cancer risk

76
Q

Characteristics associated with Peutz-Jeghers syndrome?

A

GI hamartoma polyposis, dark pigmentation around mucous membranes

77
Q

Surgical options for Peutz-Jeghers?

A

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

78
Q

Other cancers associated with Peutz-Jeghers?

A

Gonadal, breast, biliary

79
Q

Characteristics associated with Cronkite-Canada syndrome?

A

Hamartomatous polyps, atrophy of nails and hair, hypopigmentation

80
Q

Malignant potential with Cronkite-Canada syndrome?

A

NO malignant potential

81
Q

Diet associated with sigmoid volvulus?

A

High-fiber (Iran, Iraq)

82
Q

Radiographic findings with sigmoid volvulus?

A

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

83
Q

Treatment for sigmoid volvulus?

A

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

84
Q

% of sigmoid volvulus that will decompress with colonoscopy?

A

80% reduce, 50% recur

85
Q

Age range for cecal volvulus?

A

20-30y

86
Q

% of cecal volvulus that will decompress with colonoscopy?

A

20%

87
Q

Treatment for cecal volvulus?

A

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

88
Q

Symptoms of ulcerative colitis?

A

Bloody diarrhea, abdominal pain, fever, weight loss

89
Q

Layers of colon involved in ulcerative colitis?

A

Mucosa, submucosa

90
Q

Location of UC?

A

Colon only with rare backwash ilitis

91
Q

Anatomic distribution of UC?

A

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

92
Q

Rectal involvement in UC?

A

90%

93
Q

Endoscopic features of UC?

A

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

94
Q

Findings on barium enema of UC?

A

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

95
Q

Medical treatment of UC?

A

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

96
Q

Clinical diagnosis of toxic megacolon?

A

Fever, tachycardia, dilated colon on abd xray

97
Q

Treatment of toxic megacolon?

A

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

98
Q

Pathologic features of Crohn’s disease?

A

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

99
Q

Distinguishing characteristics of Crohn’s colitis?

A

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

100
Q

Endoscopic features of Crohn’s disease?

A

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

101
Q

Perforation occurs where in UC?

A

Transverse colon

102
Q

Perforation occurs where in Crohn’s?

A

Distal ileum

103
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

104
Q

Treatment for infectious pouchitis?

A

Flagyl

105
Q

Cancer risk for UC/Crohn’s?

A

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

106
Q

Surveilance for UC/Crohn’s?

A

Annual colonoscopy 8-10y after diagnosis

107
Q

Most common extraintestinal manifestation requiring total colectomy?

A

Failure to thrive in children

108
Q

Extraintestinal manifestations that DO NOT get better with colectomy?

A

PSC, ankylosing spondylitis

109
Q

Extraintestinal manifestations that get better with colectomy?

A

Most ocular problems, arthritis, anemia

110
Q

HLA associated with sacroiliitis and ankylosing spondylitis?

A

HLA B27

111
Q

Treatment for pyoderma gangrenosum?

A

Steroids

112
Q

% of carcinoids found in colon and rectum?

A

15% of all carcinoids

113
Q

Treatment for low rectal carcinoids <2cm?

A

WLE with negative margins

114
Q

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

A

APR

115
Q

Treatment for colon or high rectal carcinoids?

A

Formal resection with adenectomy

116
Q

What is the Law of LaPlace?

A

Tension = Pressure x Diameter

117
Q

Where is colon perforation with obstruction most likely to occur?

A

Cecum

118
Q

Causes of colonic obstruction?

A

1 Cancer, #2 diverticulitis

119
Q

What is pneumatosis intestinalis?

A

Air on the bowel wall, associated iwth ischemia and dissection of air through areas of bowel wall injury

120
Q

What does air in the portal system indicate?

A

Significant infection or necrosis of lthe large or small bowel

121
Q

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

A

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

122
Q

% that are carriers for Entameoba histolytica?

A

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

123
Q

Where does the primary infection occur in amoebic colitis?

A

Colon

124
Q

Where does the secondary infection occur in amoebic colitis?

A

Liver

125
Q

Risk factors for amoebic colitis?

A

Travel to Mexico, EtOH, fecal oral transmission

126
Q

Symptoms of amoebic colitis?

A

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

127
Q

Diagnosis of amoebic colitis?

A

Endoscopy: ucleration, trophozoites; antiamebic antibodies

128
Q

Treatment for amoebic colitis?

A

Flagyl, diiodohydroxyquin

129
Q

Presentation of actinomyces?

A

Mass, abscess, fistula, induration; suppurative and granulomatous

130
Q

Most common location of actinomyces?

A

Cecum

131
Q

Treatment for actinomyces

A

Tetracycline or penicillin, drainage

132
Q

Treatment for lymphogranuloma venereum?

A

Doxycycline, hydrocortisone

133
Q

Presentation of lymphogranuloma venereum?

A

Proctitis, tenesmus, bleeding; may produce fistulas

134
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

135
Q

Where to most diverticula occur?

A

L. side (80%) in sigmoid

136
Q

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

A

Right

137
Q

Diverticula present in what % of the population?

A

35%

138
Q

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

A

3 weeks

139
Q

Where is the bleeding from in hematemeis?

A

Pharynx to ligament of Treitz

140
Q

How much blood do you need to make melena?

A

50cc

141
Q

What causes azotemia after GI bleed?

A

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

142
Q

Arteriography will detect bleeding at what rate?

A

> 0.5ml/min

143
Q

Tagged RBC scan will detect bleeding at what rate?

A

> 0.1ml/min

144
Q

What causes diverticulitis?

A

Perforations in the mucosa in the diverticulum with adjacent fecal contamination

145
Q

% of patients that will have a complication of diverticulitis?

A

25%, most commonly abscess formation

146
Q

Signs of complications?

A

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

147
Q

Treatment of uncomplicated diverticulitis?

A

Flagys, bactrim, bowel rest for 3-4 days

148
Q

Indications for surgery for diverticulitis?

A

Recurrent disease, emergent complications, inability to exclude cancer

149
Q

Characteristics of colovesicular fistula?

A

Fecaluria, pneumonuria; more common in men

150
Q

Treatment for colovesicular fistula?

A

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

151
Q

Most common cause of lower GI bleeding?

A

Diverticulosis

152
Q

% of diverticular bleeding that stops? Recurs?

A

75%, 25%

153
Q

Cause of bleeding from diverticulosis?

A

Disrupted vasa rectum, creates arterial bleeding

154
Q

Diagnosis of diverticular bleeding?

A

Colonoscopy or angio 1st (therapeutic and will localize bleeding)

155
Q

When is surgery necessary for diverticular bleeding?

A

If hypotensive and not responding to resuscitation; subtotal colectomy if source has not been localized

156
Q

Characteristics of angiodysplasia bleeding?

A

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

157
Q

Soft signs of angiodysplasia on angiogram?

A

Tufts, slow emptying

158
Q

Associated cardiac anomaly with angiodysplasia?

A

Aortic stenosis in 20-30%

159
Q

Causes of ischemic colitis?

A

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

160
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)

161
Q

Symptoms of pseudomembranous colitis?

A

Watery, green, mucoid diarrhea; pain and cramping

162
Q

Key finding of pseudomembranous colitis?

A

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

163
Q

Most common location of pseudomembranous colitis?

A

Distal colon

164
Q

How is the diagnosis of pseudomembranous colitis made?

A

Fecal leukocytes, stool cultures of C. dif/toxin

165
Q

Treatment of pseudomembranous colitis?

A

IV flagyl, PO vanco or flagyl; lactobacillus

166
Q

When does neutropenic typhlitis (enterocolitis) occur?

A

Following chemo when WBCs are low

167
Q

Radiographic finding of neutropenic typhlitis?

A

Pneumoatosis on plain film

168
Q

Treatment of neutropenic typhlitis?

A

Abx; pts will improve when WBC increase

169
Q

How does TB enteritis present?

A

Like Crohn’s disease (stenosise)

170
Q

Treatment of TB enteritis?

A

INH, rifampin; surgery with obstruction

171
Q

How can Yersinia present?

A

Mimics appendicitis

172
Q

Treatment of Yersinia?

A

Bactrim or tetracyclin

173
Q

Causes of megacolon?

A

Hirschsprung’s disease, trypanosoma cruzi (most common acquired cause, secondary to destruction of nerves)