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06 - absite > chapter 36: colorectal > Flashcards

chapter 36: colorectal Flashcards

1
Q

Colon secretes ____ and reabsorbs _____

A

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

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2
Q

4 layers of the colon

A

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

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3
Q

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

A

muscularis mucosa

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4
Q

colonic layer: circular layer of muscle

A

muscularis propria

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5
Q

retroperitoneal portions of colon

A

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

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6
Q

transverse bands that form haustra

A

plicae semiliunares

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7
Q

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

A

taenia coli

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8
Q

cm: dentate line from anal verge

A

2cm

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9
Q

cm: anal transition zone from anal verge

A

4 cm

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10
Q

vasculature: ascending and 2/3 of transverse colon

A

SMA (ileocolic, right and middle colic arteries)

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11
Q

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

A

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

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12
Q

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

A

marginal artery

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13
Q

artery: short direct connection between SMA and IMA

A

Arc of Riolan

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14
Q

how is vascular supply distributed in the colon?

A

80% of blood flow goes to mucosa and submucosa

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15
Q

venous drainage of colon?

A

follows arterial except IMV, which goes to the splenic vein

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16
Q

what forms the portal vein?

A

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

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17
Q

what does superior rectal artery branch off of?

A

superior rectal artery - branch of IMA

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18
Q

what is the middle rectal artery a branch of?

A

branch of internal iliac

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19
Q

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

A

the lateral stalks

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20
Q

what is the inferior rectal artery a branch of?

A

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

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21
Q

where do superior and middle rectal veins drain?

A

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

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22
Q

where do inferior rectal veins drain?

A

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

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23
Q

major blood supply of the colon

A

SMA and IMA

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24
Q

drain to IMA nodal lymphatics

A

superior and middle rectum

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25
Q

drains primarily to IMA nodes, also to internal iliac nodes

A

lower rectum

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26
Q

does the bowel wall contain lymphatics?

A

bowel wall contains mucosal and submucosal lymphatics.

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27
Q

what are the watershed areas in the colon?

A
  • splenic flexure (Griffith’s point)

- rectum (Sudak’s point)

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28
Q

watershed area: SMA and IMA junction

A

splenic flexure (Griffith’s point)

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29
Q

watershed area: superior rectal and middle rectal junction

A

rectum (sudak’s point)

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30
Q

more sensitive to ischemia: colon vs small bowel

A

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

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31
Q

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

A

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

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32
Q
  • involuntary control
  • is the continuation of the muscularis propria (smooth muscle)
  • is normally contracted
A

internal sphincter

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33
Q

inner nerve plexus

A

meissner’s plexus

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34
Q

outer nerve plexus

A

auerbach’s plexus

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35
Q

parasympathetic to colon

A

pelvic splanchnic nerves

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36
Q

sympathetics to colon

A

lumbar and sacral plexus

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37
Q

from anal verge: anal canal

A

0 - 5 cm

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38
Q

from anal verge: rectum

A

5 - 15 cm

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39
Q

from anal verge: rectosigmoid junction

A

15 - 18 cm

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40
Q

marks the transition between anal canal and rectum

A

levator ani

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41
Q

mucus-secreting goblet cells

A

crypts of lieberkuhn

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42
Q

slow transit time; patients may need subtotal colectomy

A

colonic inertia

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43
Q

main nutrient of colonocytes

A

short-chain fatty acids

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44
Q

tx: stump pouchitis (diversion or disuse proctitis)

A

short-chain fatty acids

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45
Q

tx: infectious pouchitis

A

metronidazole (flagyl)

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46
Q

rectovesicular fascia in men; rectovaginal fascia in women

A

denonvilliers fascia (anterior)

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47
Q

rectosacral fascia

A

waldeyer’s fascia (posterior)

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48
Q

most common polyp; no cancer risk

A

hyperplastic polyps

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49
Q

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

A

tubular adenoma

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50
Q

polyp most likely to produce symptoms

- these are generally sessile and larger than tubular adenomas

A

villous adenoma

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51
Q

villous adenomas: percent that have cancer

A

50% of villous adenomas have cancer

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52
Q

polyps: characteristics of lesions with increased cancer risk

A

> 2cm
sessile
villous

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53
Q

polyps have ___ side predominance

A

polyps have left side predominance

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54
Q

what type of polyps can be removed endoscopically?

A

most pedunculated polyps can be removed endoscopically

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55
Q

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

A

need segmental resection

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56
Q

when is polypectomy adequate treatment for invasive carcinoma?

A

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

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57
Q

polyps: basement membrane is intact (carcinoma in situ)

A

high-grade dysplasia

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58
Q

what is carcinoma in situ?

A

malignant cells are confined to the mucosa

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59
Q

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

A

intramucosal cancer

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60
Q

polyps: into submucosa (T1)

A

invasive cancer

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61
Q

colon cancer screening recommendations

A

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

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62
Q

colon cancer screening options

A

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

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63
Q

what can cause a false-positive guaiac?

A

beef, vitamin C, iron, cimetidine

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64
Q

when do you not want to do colonoscopy?

A

recent MI, splenomegaly, pregnancy (if fluoroscopy planned)

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65
Q

management: polypectomy shows T1 lesion

A

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

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66
Q

tx: extensive low rectal villous adenomas with atypia

A 
transanal excision (can try mucosectomy) as much of the polyp as possible. 
- NO APR unless cancer is present.
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67
Q

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

A

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

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68
Q

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

A

patient needs APR or LAR

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69
Q

2nd leading cause of CA death

A

colorectal cancer

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70
Q

symptoms of colorectal cancer

A

anemia, constipation, and bleeding

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71
Q

why are red meat and fat associated with colorectal cancer?

A

O2 radicals are thought to have a role

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72
Q

what infection is associated with colorectal cancer?

A

clostridium septicum infection

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73
Q

main gene mutations in colorectal cancer

A

APC, DCC, p53, and k-ras

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74
Q

most common site of primary colorectal cancer

A

sigmoid colon

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75
Q

most important prognostic factor for colorectal cancer

A

nodal status

- spreads to nodes first

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76
Q

primary sites of metastases in colorectal cancer

A 
#1 liver
#2 lung
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77
Q

how does colorectal cancer metastasize to liver?

A

portal vein

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78
Q

how does colorectal cancer metastasize to lung?

A

iliac vein

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79
Q

5 year survival rate for colorectal cancer with liver metastases

A

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

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80
Q

5 year survival rate for colorectal cancer with lung metastases

A

25% 5-YS rate in selected patients after resection

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81
Q

management: isolated liver or lung metastases in colorectal cancer

A

isolated liver or lung mets should be resected

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82
Q

rate of patients with drop metastases to ovaries in colorectal cancer

A

5%

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83
Q

why can rectal CA metastasize to spine directly?

A

via Batson’s plexus (venous)

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84
Q

does colon CA go to bone?

A

colon CA typically does not go to bone

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85
Q

surgery: colorectal CA growing into adjacent organs

A

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

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86
Q

colorectal ca prognosis: lymphocytic penetration

A

patients have an improved pronosis

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87
Q

colorectal ca prognosis: mucoepidermoid

A

worst prognosis

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88
Q

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

A

rectal ultrasound

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89
Q

mandatory in diagnosis of colorectal ca

A

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

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90
Q

colorectal ca: goals of resection

A

en bloc resection, adequate adenectomy

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91
Q

management of most right-sided colon CAs

A

can be treated with primary anastomosis without ostomy

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92
Q

management of rectal pain with rectal ca

A

patient needs APR

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93
Q

margins for colorectal cancer surgery

A

generally need 2-cm margins

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94
Q

colorectal ca: best method of picking up intrahepatic metastases

A

intraoperative ultrasound (U/S)

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95
Q

intraoperative ultraound

- resolution: conventional U/S

A

10 mm

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96
Q

intraoperative ultraound

- resolution: abdominal CT

A

5-10mm

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97
Q

intraoperative ultraound

- resolution: abdominal MRI

A

5-10mm (better resolution than CT)

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98
Q

intraoperative ultraound

- resolution: intraoperative U/S

A

3-5mm

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99
Q

permanent colostomy; anal canal is excised along with the rectum

A

abdominoperineal resection (APR)

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100
Q

potential complications of abdominoperineal resection (APR)

A

can have impotence and bladder dysfunction (injured pudendal nerves)

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101
Q

when is abdominoperineal resection indicated?

A

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

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102
Q

margins for abdominoperineal resection (APR)

A

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

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103
Q

risk of local recurrence: rectal CA vs colon CA

A

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

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104
Q

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

A

preoperative chemo-XRT

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105
Q

T? - into submucosa

A

T1

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106
Q

T? - into muscularis propria

A

T2

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107
Q

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

A

T3

108
Q

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

A

T4

109
Q

N? - nodes negative

A

N0

110
Q

N? - 1-3 nodes positive

A

N1

111
Q

N? - >/ 4 nodes positive

A

N2

112
Q

N? - central nodes positive

A

N3

113
Q

M? - distant metastases

A

M1

114
Q

tx: low rectal T1 (limited to submucosa)

A

can be excised transanally if

115
Q

tx: low rectal T2 or higher

A

APR or LAR

116
Q

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

A

postop chemo, no XRT

117
Q

chemotherapy: stage 2 and 3 rectal ca

A

pre-op chemo-XRT

118
Q

chemotherapy: stage 4 and rectal CA

A

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

119
Q

colorectal CA: chemo regimen

A

5FU, leucovorin, and oxaliplatin (FOLFOX)

120
Q

colorectal CA: benefits XRT

A

decreases local recurrence and increases survival when combined with chemotherapy

121
Q

colorectal CA: XRT damage

A

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

122
Q

colorectal CA: pre-op chemo XRT

A

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

123
Q

colorectal CA: rate of recurrence

A

20% have a recurrence (usually occurs within 1 year)

- 5% get another primary -> main reason for surveillance colonoscopy

124
Q

why does colorectal ca require surveillance?

A

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
Q

autosomal dominant; all have cancer by age 40

A

familial adenomatous polyposis (FAP)

126
Q

gene involved in FAP

A

APC gene - chromosome 5

127
Q

how many FAP syndromes are spontaneous?

A

20% of FAP syndromes are spontaneous

128
Q

when do FAP syndromes present?

A

polyps not present at birth; are present in puberty

129
Q

do you need colonoscopy surveillance in FAP?

A

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

130
Q

management of FAP

A

all need total colectomy prophylactically at age 20

131
Q

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

A

also get duodenal polyps

132
Q

FAP surgery

A

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
Q

MCC death in FAP patients following colectomy

A

periambpullary tumors of the duodenum

134
Q

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

A

Gardner’s syndrome

135
Q

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

A

Turcot’s syndrome

136
Q

5% of the population, autosomal dominant

  • associated with DNA mismatch repair gene
  • predilection for right-sided and multiple cancers
A

Lynch syndromes (hereditary nonpolyposis colon cancer)

137
Q

Lynch syndrome: just colon CA risk

A

Lynch 1

138
Q

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

A

Lynch 2

139
Q

Amsterdam criteria for Lynch syndrome

A

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

140
Q

surveillance for lynch syndrome

A

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
Q

rate of metachronous lesions in lynch syndrome

A

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

142
Q

surgery for lynch syndrome

A

need total proctocolectomy with first cancer operation

143
Q
  • more common with high-fiber diets (Iran, Iraq)
  • occurs in debilitated psychiatric patients, neurologic dysfunction, laxative abuse
  • symptoms: pain, distention, and obstipation
A

sigmoid volvulus

144
Q

what type of obstruction is sigmoid volvulus?

A

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

145
Q

abdominal Xr: sigmoid volvulus

A

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

146
Q

management of gangrenous bowel in sigmoid volvulus

A

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

147
Q

tx: sigmoid volvulus

A

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

148
Q

less common than sigmoid volvulus; occurs in 20s-30s

- can appear as SBO with dilated cecum in the RLQ

A

cecal volvulus

149
Q

role of colonoscopy in cecal volvulus

A

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

150
Q

OR treatment for cecal volvulus

A

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

151
Q

bloody diarrhea, abdominal pain, fever and weight loss

  • involves the mucosa and submucosa
  • strictures and fistulae unusual
A

ulcerative colitis

152
Q

IBD: spares anus

A 
ulcerative colitis (unlike crown's)
- usually starts distally in rectum and is contiguous (no skip areas like crohn's)
153
Q

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

A

ulcerative colitis

154
Q

what do you need to rule out in ulcerative colitis?

A

always need to rule out infectious etiology

155
Q

ulcerative colitis: when can backwash ileitis occur?

A

backwash ileitis can occur with proximal disease

156
Q

characteristics of barium enema in chronic ulcerative colitis

A

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

157
Q

medical treatment: ulcerative colitis

A

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

158
Q

ulcerative colitis: medical treatment that can maintain remission

A

5-ASA and sulfasalazine

159
Q

ulcerative colitis: medical treatment for steroid-resistant disease

A

consider cyclosporine or infliximab

160
Q

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

A

toxic colitis

161
Q

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

A

toxic megacolon

162
Q

toxic colitis and toxic megacolon: initial treatment

A

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
Q

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

A

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

164
Q

absolute indications for surgery with toxic colitis and toxic megacolon

A

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

165
Q

relative indications for surgery with toxic colitis and toxic megacolon

A

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
Q

more common location of perforation with ulcerative colitis

A

transverse colon more common

167
Q

more common location of perforation with crohn’s disease

A

distal ileum most common

168
Q

surgical indications for ulcerative colitis

A

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
Q

ulcerative colitis: emergent/urgent resection

A

total proctocolectomy and bring up ileostomy

- perform definitive hook-up later

170
Q

elective resection: ulcerative colitis

A

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

171
Q

what does illeoanal anastomosis protect in ulcerative colitis?

A

can protect bladder and sexual function

172
Q

ulcerative colitis: why do many illeoanal anastomoses need resection?

A

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

173
Q

mc major morbidity in illeoanal anastomosis in ulcerative colitis

A

can lead to sepsis (Tx: drainage, antibiotics)

174
Q

ulcerative colitis: tx - infectious pouchitis

A

flagyl

175
Q

two options with elective resections in ulcerative colitis

A

ileoanal anastomosis and APR with ileostomy

176
Q

cancer risk in ulcerative colitis

A

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
Q

most common extra intestinal manifestation of ulcerative colitis requiring total colectomy

A

failure to thrive in children

178
Q

ulcerative colitis: do not get better with colectomy

A

primary sclerosing cholangitis, ankylosing spondylitis

179
Q

ulcerative colitis: get better with colectomy

A

most ocular problems, arthritis, and anemia

180
Q

ulcerative colitis: 50% get better

A

pyoderma gangrenosum

181
Q

ulcerative colitis: HLA b27

A

sacroilitis, ankylosing spondylitis, ulcerative colitis

182
Q

is thromboembolic disease a risk in ulcerative colitis?

A

yes

183
Q

tx: pyoderma gangrenosum in ulcerative colitis

A

steroids

184
Q

represents 15% of all carcinoids; infrequent cause of carcinoid syndrome

  • metastases related to size of tumor
  • 2/3 have either local or systemic spread
A

carcinoid of the colon and rectum

185
Q

treatment: low rectal carcinoids

A

wide local excision with negative margins

186
Q

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

A

APR

187
Q

tx: colon or high rectal carcinoids

A

formal resection with adenectomy

188
Q

location: colon perforation with obstruction

A

most likely to occur in cecum

189
Q

law of laplace

A

tension = pressure x diameter

190
Q

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

A

closed loop-obstruction

191
Q

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

A

competent ileocecal valve

192
Q

primary causes of colonic obstruction

A 
#1 cancer
#2 diverticulitis
193
Q

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

A

pneumatosis intestinalis

194
Q

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

A

air in the portal system

195
Q

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
A

ogilvie’s syndrome

196
Q

tx: ogilvie’s syndrome

A

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

197
Q

high risk of perforation in ogilvie’s syndrome

A

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

198
Q
  • from contaminated food and water with feces that contain cysts
  • risk factors: travel to Mexico, ETOH; fecal-oral transmission
A

amoebic colitis: entamoeba histolytica

199
Q

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

A

amoebic colitis - entamoeba histolytica

200
Q

primary and secondary infection of amoebic colitis

A
  • primary infection - occurs in colon

- secondary infection - occurs in liver

201
Q

dx: amoebic colitis

A

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

202
Q

tx: amoebic olitis

A

flagyl, diiodohydroxyquin

203
Q

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

A

actinomyces

204
Q

most common location of actinomyces

A

cecum most common location; can be confused with CA

205
Q

pathology: actinomyces

A

yellow-white sulfur granules

206
Q

tx: actinomyces

A

penicillin or tetracycline, drainage of any abscess

207
Q

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

A

diverticula

208
Q

how is adjacent colon affected by diverticula?

A

circular muscle thickens adjacent to diverticulum with luminal narrowing

209
Q

what causes diverticula?

A

caused by straining (increased intraluminal pressure)

210
Q

where do most diverticula occur?

A

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

211
Q

symptoms: right-sided diveritucula

A

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

212
Q

diverticula: more likely to present on the left side

A

diverticulitis

213
Q

rate of diverticula in the populations

A

presents in 35% of the population

214
Q

lower GIB: how long does stool guaic stay positive

A

for up to 3 weeksn

215
Q

bleeding anywhere near pharynx to ligament of Treitz

A

hematemsis

216
Q

passage of tarry stools; need as little as 50 cc

A

melena

217
Q

management of lower gastrointestinal hemorrhage

A
  • rule out UGI: NGT

- r/o rectal source: proctoscopy

218
Q

what causes azotemia after GIB?

A

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

219
Q

bleeding rate to see arteriography

A

bleeding must be >/ 0.5 cc/min

220
Q

bleeding rate for tagged RBC scan

A

bleeding must be >/ 0.1 cc/min

221
Q

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

A

diverticulitis

222
Q

what causes diverticulitis

A

result of mucosal perforations in the diverticulum with adjacent fecal contamination

223
Q

dx: diverticulitis

A

CT scan is needed only if worried about complications of disease

224
Q

follow-up after episode of diverticulitis

A

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

225
Q

most common complication of diverticulitis

A

abscess formation; can usually percutaneously drain

226
Q

signs of complications of diverticulitis

A

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

227
Q

tx: uncomplicated diverticulitis

A

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

228
Q

indications for surgery in diverticulitis

A

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
Q

surgery: diverticulitis

A

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

230
Q

80% discovered at time of incision for appendectomy

A

right-sided diverticulitis

- tx: right hemicolectomy

231
Q

fecaluria, pneumouria

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

A

colovesicular fistula

232
Q

best diagnostic test for colovesicular fistula

A

cystoscopy is the best diagnostic test

233
Q

tx: colovesicular fistula

A

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

234
Q

MCC of lower GIB

A

diverticulosis (usually causes significant bleeding)

235
Q

diverticulosis bleeding: ___stops spontaneously; recurs in ___

A

75% stops spontaneously; recurs in 25%

236
Q

what causes diverticulosis bleeding?

A

caused by disrupted vasa rectum; creates arterial bleeding

237
Q

dx: diverticulosis bleeding

A

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
Q

dx: massive bleeding in diverticulosis

A

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
Q

dx: diverticulosis bleeding if hypotensive and not responding to resuscitation

A

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
Q

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

A

tagged RBC scan

241
Q

tx: diverticulosis bleeding

A

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
Q

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

A

may need segmental colectomy or possible subtotal colectomy

243
Q

management of patients with recurrent diverticular bleeds

A

should have resection of that area

244
Q
  • increased on right side of colon
  • bleeds are usually less severe than diverticular bleeds but are more likely to recur (80%)
  • causes venous bleeding
A

angiodysplasia bleeding

245
Q

soft signs of angiodysplasia on angiogram

A

tufts, slow emptying

246
Q

coexisting comorbidity in angiodysplasia

A

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

247
Q

symptoms: abdominal pain, bright red bleeding

A

ischemic colitis

248
Q

what can cause ischemic colitis?

A

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
Q

most vulnerable colonic sites to low-flow states

A

splenic flexure and upper rectum

250
Q

point: SMA and IMA junction

A

Griffith’s point (splenic flexure)

251
Q

superior rectal and middle rectal artery junction

A

sudeck’s point

252
Q

dx: ischemic colitis

A

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

253
Q

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

A

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

254
Q

ischemic colitis: management of suspected gangrenous colitis (peritonitis)

A

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

255
Q

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

A

pseudomembranous colitis (C difficle colitis)

256
Q

key finding: pseudomembranous colitis

A

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

257
Q

most common location of pseudomembranous colitis (C diff)

A

most common in the distal colon

258
Q

dx: c diff (pseudomembranous colitis)

A

c diff toxin

259
Q

tx: pseudomembranous colitis (c diff)

A

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

260
Q
  • follows chemotherapy when WBC are low (nadir)
  • can mimic surgical disease
  • can often see pneumatosis intestinalis (not a surgical indication)
A

neutropenic typhlitis (enterocolitis)

261
Q

tx: neutropenic typhlitis (enterocolitis)

A

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

262
Q

other causes of colitis

A

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

263
Q

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

A

yersinia

- tx: tetracycline or bactrim

264
Q

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

A

megacolon

265
Q

megacolon - rectosigmoid most common

- dx: rectal biopsy

A

hirschsprung’s disease

266
Q

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

A

trypanosoma cruzi

06 - absite (44 decks)

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