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36 Colorectal Flashcards

1
Q

anatomy and physiology: colon function

A

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

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2
Q

anatomy and physiology: layers

A

4 … mucosa (columnar epithelium), submucosa, muscularis propria, serosa (in to out)

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3
Q

anatomy and physiology: describe muscularis mucosa vs muscularis propria

A

musc mucosa = small interwoven inner muscle layer just below mucosa but above basement membrane … musc propria = circular layer of muscle

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4
Q

anatomy and physiology: what part is retroperitoneal?

A

ascending, descending, and sigmoid colon … peritoneum covers anterior upper and middle 1/3 of the rectum

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5
Q

anatomy and physiology: plicae semilunares

A

transverse bands that form haustra

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6
Q

anatomy and physiology: taenia coli

A

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

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7
Q

anatomy and physiology: anorectal anatomy with important landmarks

A

distance from anal verge … 2cm - dentate line …. 4cm - anorectal ring …. 8cm - end of lower 1/3 …. 12cm - end of middle 1/3 …. 16cm - end of upper 1/3

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8
Q

anatomy and physiology: vascular supply

A

ascending and 2/3 of transverse colon - SMA (ileocolic, R and middle colic arteries) …. 1/3 transverse, descending colon, sigmoid colon, upper portion of the rectum - IMA (L colic, sigmoid branches, superior rectal artery) …. marginal artery - runs along colon margin, connects SMA to IMA (provides collateral flow) …. arc of Riolan - short firect connection between SMA and IMA …. 80% of blood flow goes to mucosa and submucosa

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9
Q

anatomy and physiology: venous drainage

A

follows arterial except IMV, which goes to splenic vein … splenic vein joins the SMV to form the portal vein behind the pancreas

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10
Q

anatomy and physiology: superior rectal artery

A

branch of IMA

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11
Q

anatomy and physiology: middle rectal artery

A

branch of internal iliac - the lateral stalks during low anterior resection (LAR) or abdominoperineal resection (APR) contain the middle rectal arteries

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12
Q

anatomy and physiology: inferior rectal artery

A

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

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13
Q

anatomy and physiology: rectal venous drainage

A

superior and middle rectal veins drain into the IMV and eventually the portal vein …. inferior rectal veins drain into the internal iliac veins and eventually into the caval system

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14
Q

anatomy and physiology: nodal drainage

A

superior and middle rectum - drain into IMA nodal lymphatics …. lower rectum - drains primarily to IMA nodes and also to internal iliac nodes …. bowel wall contains mucosal and submucosal lymphatics

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15
Q

anatomy and physiology: watershed areas

A

splenic flexure aka Giffith’s point - SMA and IMA junction …. rectum aka Sudak’s point - superior rectal and middle rectal junction …colon more sensitive to ischeia than small bowel 2/2 fewer collaterals

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16
Q

anatomy and physiology: part of bowel most sensitive to ischemia

A

colon is more sensitive to ischemia than small bowel 2/2 decreased collaterals

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17
Q

anatomy and physiology: external vs internal sphincter - muscle, innervation

A

external = puborectalis muscle, continuation of levator ani (striated) muscle, under CNS control via inferior rectal branch of internal pudendal nerve …. internal = continuation of muscularis (smooth) muscle, involuntary control, normally contracted

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18
Q

anatomy and physiology: inner and outer nerve plexi

A

inner = meissner’s plexus … outer = Auerbach’s plexus

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19
Q

anatomy and physiology: sympathetic vs parasympathetic

A

sympathetic = lumbar and sacral plexi …. parasympathetic = pelvic splanchnic nerves

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20
Q

anatomy and physiology: distance from anal verge - anal canal, rectum, rectosigmoid junction

A

anal canal 0-5cm …. rectum 5-15cm … rectosigmoid junction 15-18cm

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21
Q

anatomy and physiology: levator ani

A

marks the transition between anal canal and rectum

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22
Q

anatomy and physiology: crypts of lieberkuhn

A

mucus-secreting goblet cells

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23
Q

anatomy and physiology: colonic inertia

A

slow transit time, pts may need subtotal colectomy

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24
Q

anatomy and physiology: main nutrient of colonocytes

A

short-chain fatty acids

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25
Q

anatomy and physiology: tx of infectious pouchitis

A

flagyl

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26
Q

anatomy and physiology: denonvilliers fascia and waldeneyer’s fascia

A

denonvilliers = anterior, retrovesicular in M, rectovaginal in F ….. waldeneyer’s = posterior, rectosacral

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27
Q

polyps: list types

A

hyperplastic polyp, tubular adenoma, villous adenoma

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28
Q

polyps: MC type overall vs neoplastic vs sx

A

hyperplastic MC overall (NO cancer risk) … tubular adenoma is MC intestinal neoplastic polyp (75%) …. villous adenoma is most likely to be symptomatic

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29
Q

polyps: pedunculated vs sessile

A

tubular adenoma is most often pedunculated … villous adenoma is usually sessile and larger than tubular

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30
Q

polyps: rate of cancer in villous adenoma

A

50%

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31
Q

polyps: inc cancer risk in which polyps

A

> 2cm, sessile, villous

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32
Q

polyps: more common on which side

A

L

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33
Q

polyps: which are removed endoscopically

A

pedunculated

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34
Q

polyps: mgmt when you cannot remove entire polyp

A

segmental resection (usually occurs w sessile)

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35
Q

polyps: carcinoma in situ vs invasive carcinoma - difference and mgmt

A

in situ - malignant cells confined to mucosa, tx w polypectomy ….. carcinoma - malignant cells past mucosa, can tx w polypectomy ONLY IF >2mm margin, NOT poorly differentiated, NO evidence of venous or lymphatic invasion is found

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36
Q

polyps: high grade dysplasia vs intramucosal cancer vs invasive cancer

A

high grade dysplasia = basement membrane is intact (i.e. carcinoma in situ) …. intramucosal cancer = into muscularis mucosa (carcinoma in situ, still has not gone through basement membrane) …. invasive cancer = into submucosa (T1)

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37
Q

screening

A

at 50 for normal risk, at 40 (or 10yrs before youngest case) for intermediate risk (i.e. family hx of cancer)

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38
Q

screening options

A

(1) colonoscopy every 10 years …OR … (2) high-sensitivity FOBT every 3 years AND flex sig every 5 years …. OR … (3) high-sens FOBT annually … OR … (4) double contrast barium enema or CT colonography every 5 years

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39
Q

falsa positive guaiac

A

beef, vit C, Fe, cimetidine

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40
Q

NO colonoscopy with what?

A

recent MI, splenomegaly, pregnancy (if fluoroscopy planned)

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41
Q

mgmt if polypectomy shows T1 lesion

A

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

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42
Q

mgmt of 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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43
Q

mgmt if pathology shows T1 lesion after transanal excision of rectal polyp

A

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

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44
Q

mgmt if pathology shows T2 lesions after transanal excision of rectal polyp

A

pt needs APR and LAR

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45
Q

rate of cancer death

A

colorectal cancer is 2nd MC cause of cancer death

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46
Q

colorectal cancer: sx

A

anemia, constipation, bleeding

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47
Q

colorectal cancer: diet risk

A

red meat and fat … O2 radicals are thought to play a role

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48
Q

colorectal cancer: assoc with which infections

A

assoc w clostridium septicum infection

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49
Q

colorectal cancer: gene mutations

A

APC, DCC, p53, k-ras

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50
Q

colorectal cancer: MC primary site

A

sigmoid colon

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51
Q

colorectal cancer: disease spread - 1st spread

A

nodes

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52
Q

colorectal cancer: disease spread - most important prognostic factor

A

nodal status

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53
Q

colorectal cancer: disease spread - MC sites of mets and route of spread

A

1 = liver via portal vein … #2 = lung via iliac vein

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54
Q

colorectal cancer: disease spread - prognosis of liver mets vs lung mets

A

if resectable and leaves adequate liver function - 35% 5yr survival ….. after resection lung mets - 25% 5yr survival

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55
Q

colorectal cancer: disease spread - mgmt of isolated liver or lung mets

A

resect

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56
Q

colorectal cancer: disease spread - rate of mets to ovaries

A

5% with drop mets to ovaries

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57
Q

colorectal cancer: disease spread - bone mets in rectal CA and colon CA mets

A

rectal CA - can met to spine directly via Batson’s plexus (venous) … colon CA - usually does NOT go to bone

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58
Q

colorectal cancer: disease spread - mgmt of colon CA spread 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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59
Q

colorectal cancer: disease spread - worst vs better prognosis

A

mucoepidermoid is worst prognosis … lymphocytic penetration has improved prognosis

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60
Q

colorectal cancer: disease spread - use of rectal U/S

A

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

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61
Q

colorectal cancer: workup

A

need total colonoscopy to r/o synchronous lesions

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62
Q

colorectal cancer: goals of resection

A

en bloc resection, adequate margins, regional adenectomy …. most R sided colon CAs can be treated with primary anastomosis without ostomy …. rectal pain w rectal CA requires APR …. generally need 2cm margins

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63
Q

colorectal cancer: best method of detecting intrahepatic mets

A

intraop U/S

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64
Q

colorectal cancer: resolution of different imaging techniques

A

conventional U/S 10mm …. abd CT 5-10mm …. abd MRI 5-10mm (better resolution than CT) … intraop U/S 3-5mm

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65
Q

colorectal cancer: APR - describe

A

permanent colostomy, anal cancal is excised along with the rectum

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66
Q

colorectal cancer: APR - complications

A

impotence and bladder dysfunction 2/2 injured pudendal nerves

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67
Q

colorectal cancer: APR - indications

A

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

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68
Q

colorectal cancer: APR - margins

A

need at least 2cm margin (2cm from levator ani muscles) for LAR, o/w will need APR

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69
Q

colorectal cancer: APR - risk of local recurrence

A

higher risk with rectal CA then colon CA

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70
Q

colorectal cancer: preop chemo-XRT

A

produced complete response in some pts w rectal CA, reserves sphincter function in some

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71
Q

colorectal cancer: TNM staging

A

T1 = into submucosa, T2 = into muscularis propria, T3 = into serosa or through muscularis propria, T4 = through serosa and into free peritoneal cavity or into adjacent organs/structures if no serosa is present ….. N0 = nodes negative, N1 = 1-3 nodes positive, N2 = >=4 nodes positive, N3 = central nodes positive …. M1 = distant mets

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72
Q

colorectal cancer: stages

A

0 = Tis, N0, M0 … 1 = T1-2, N0, M0 … 2a = T3, N0, M0 … 2b = T4, N0, M0 …. 3a = T1-2, N1, M0 … 3b = T3-4, N1, M0 … 3c = ant T, N2, M0 …. 4 = any T, any N, M1

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73
Q

colorectal cancer: low rectal T1

A

limited to submucosa, can be excised transanally if <4cm, has negative margins (need 1cm), is well differentiated, and there is no neurologic or vascular invasion, otherwise pt needs and APR or LAR

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74
Q

colorectal cancer: low rectal T2 or higher

A

LAR or APR

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75
Q

colorectal cancer: chemotherapy

A

stage 3 and 4 colon CA - node positive or distant mets —> postop chemo, NO XRT ….. stage 2 and 3 rectal CA —> preop chemo-XRT …. stage 4 rectal CA —> chemo and XRT +/- surgery (possibly just colostomy, may want to avoid APR in pts w metastatic disease) …. chemo = 5FU, leucovorin, and oxalplatin (FOLFOX)

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76
Q

colorectal cancer: XRT - role, damage, indications

A

decreased local recurrence and increased survival when combined with chemo …. XRT damage - rectum most common site of injury 2/2 vasculitis, thrombosis, ulcers, strictures …. pre-op chemo-XRT may help shrink rectal tumors, allows for down-staging of the tumor and possible allowing for LAR or APR

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77
Q

colorectal cancer: recurrence rate

A

20%, usually within 1 year, 5% get another primary (main reason for surveillance colonoscopy)

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78
Q

colorectal cancer: follow-up colonoscopy - timing and reason

A

1 year, main purpose is to check for new primary colon CA (metachronous lesion)

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79
Q

familial adenomatous polyposis (FAP): inheritence

A

autosomal dominant, APC gene, chromosome 5 …. 20% are spontaneous

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80
Q

familial adenomatous polyposis (FAP): cancer rate

A

all have cancer by age 40

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81
Q

familial adenomatous polyposis (FAP): polyp presentation

A

NOT present at birth, present at puberty

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82
Q

familial adenomatous polyposis (FAP): surveillance

A

do NOT need colonoscopy for surveillance in pts w suspected FAP …. just need flex sig

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83
Q

familial adenomatous polyposis (FAP): mgmt

A

ppx total colectomy at age 20

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84
Q

familial adenomatous polyposis (FAP): other sites of polyps

A

duodenal polyps –> check duo w endoscopy every 2 years

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85
Q

familial adenomatous polyposis (FAP): surgical mgmt

A

proctocolectomy, rectal mucosectomy, ileoanal pouch (J pouch) …. need lifetime surveillance of residual rectal mucosa …. another option is total proctocolectomy with end ileostomy

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86
Q

familial adenomatous polyposis (FAP): MC cause of death after colectomy

A

periampullary duodenal tumors

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87
Q

familial adenomatous polyposis (FAP): Gardner’s and Turcot’s syndromes

A

Gardner’s = pts get colon CA (assoc w APC gene) and desmoid tumors/osteomas …. Turcot’s = pts get colon CA (assoc w APC gene) and brain tumors

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88
Q

lynch syndrome: aka

A

HNPCC = hereditary nonpolyposis colon cancer

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89
Q

lynch syndrome / HNPCC: rate

A

5% of population

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90
Q

lynch syndrome / HNPCC: inheritance

A

autosomal dominant

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91
Q

lynch syndrome / HNPCC: genetics

A

DNA mismatch repair gene

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92
Q

lynch syndrome / HNPCC: which side

A

MC on R side, MC multiple

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93
Q

lynch syndrome / HNPCC: type 1 and 2

A

1 = just colon CA risk …. 2 = patients also have inc risk of ovarian, endometrial, bladder, stomach cancer

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94
Q

lynch syndrome / HNPCC: amsterdam criteria

A

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

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95
Q

lynch syndrome / HNPCC: surveillance

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)

96
Q

lynch syndrome / HNPCC: cancer rate

A

50% with metachronous lesions within 10 years, often with multiple primaries

97
Q

lynch syndrome / HNPCC: surgical mgmt

A

need total proctocolectomy with first cancer operation

98
Q

which type of volvulus is most common

A

cecal less common than sigmoid

99
Q

sigmoid volvulus: most common with which diets

A

high-fiber (Iran, Iraq)

100
Q

sigmoid volvulus: MC pts

A

debilitated psych pts, neurologic dysfunction, laxative abuse

101
Q

sigmoid volvulus: sx

A

pain, distention, obstipation

102
Q

sigmoid volvulus: pathophys

A

sigmoid colon twists on itself —> closed loop obstruction

103
Q

sigmoid volvulus: abd xray findings

A

bent inner tube sign

104
Q

sigmoid volvulus: gastrograffin enema

A

bird’s beak sign, tapered colon

105
Q

sigmoid volvulus: mgmt

A

decompress with colonoscopy - 80% reduce, 50% will recur, give bowel prep and perform sigmoid colectomy during same admission …. gangrenous bowel or peritoneal signs: do NOT attempt decompression —> go to OR for sigmoidectomy

106
Q

cecal volvulus: MC age

A

20s-30s

107
Q

cecal volvulus: px

A

can appear as SBO with dilated cecum in the RLQ

108
Q

cecal volvulus: decompression

A

can try to decompress with colonoscopy but only 20% success rate

109
Q

cecal volvulus: tx

A

OR for R hemicolectomy is usually best, can try cecopexy if colon is viable and pt is frail

110
Q

UC: sx

A

bloody diarrhea, abd pain, fever, weight loss

111
Q

UC: involves which parts

A

mucosa or submucosa

112
Q

UC: strictures and fistulae

A

unusual in UC

113
Q

UC: location of disease

A

spares anus (unlike Crohn’s), usually starts in distal rectum and is contiguous (no skip lesions like Crohn’s)

114
Q

UC: bleeding

A

universal, has mucosal friability with pseudopolyps and collar button ulcers

115
Q

UC: workup

A

always need to r/o infectious etiology

116
Q

UC: backwash ileitis

A

can occur w proximal disease

117
Q

UC: barium enema

A

with chronic disease you see many haustra, narrow caliber, short colon, loss of redundancy

118
Q

UC: medical tx

A

sulfasalazine (or 5-ASA) and loperamide for maintenance …. steroid for acute flares …. 5-ASA and sulfasalazine can maintain remission in UC … consider cyclosporine or infliximab for steroid-resistant disease

119
Q

UC: toxic colitis and toxic megacolon - describe

A

toxic colitis = >6 bloody stools/day, fever, inc HR, drop in Hb, leukocytosis … toxic megacolon = above plus distention, abd pain, tenderness

120
Q

UC: toxic colitis and toxic megacolon - initial tx

A

NGT, fluids, steroids, bowel rest, abx (cipro and flagyl) will treat 50% adequately, 50% need surgery

121
Q

UC: toxic colitis and toxic megacolon - monitor response to tx

A

clinical response, abdominal radiographs

122
Q

UC: toxic colitis and toxic megacolon - avoid what

A

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

123
Q

UC: toxic colitis and toxic megacolon - indications for surgery

A

absolute = pneumoperitoneum, diffuse peritonitis, localized peritonitis with increasing abd pain and/or colonic distention >10cm, uncontrolled sepsis, major hemorrhage …. relative = inability to promptly control sepsis, increasing megacolon, failure to improve within 24-48 hours, increasing toxicity or other signs of clinical deterioration, continued transfusion requirements

124
Q

UC: surgical indications

A

massive hemorrhage, refractory toxic megacolon, acute fulminant UC (occurs in 15%), obstruction, ANY dysplasia, cancer, intractability, systemic complications, failure to thrive, long-standing disease (>10yrs) as ppx against colon cancer (some controversy)

125
Q

MC site of perforation - Crohn’s vs UC

A

distal ileum vs transverse colon

126
Q

UC: emergent/urgent resections

A

total proctocolectomy and drink up ileostomy, perform definitive hook up later

127
Q

UC: elective resections

A

ileoanal anastomosis or APR with ileostomy

128
Q

UC: elective resections - ileoanal anastomosis - describe, benefits, surveillance, resection

A

rectal mucosectomy, J pouch, and ileoanal (low rectal) anastomosis (NOT used with Crohn’s disease) … can protect bladder and sexual function … need lifetime surveillance of residual rectal area …. many ileoanal anastomoses need resection 2/2 cancer, dysplastic changes, refractory pouchitis, pouch failure (incontinence) …. need temporary diverting ileostomy 6-8 weeks while pouch heals .

129
Q

UC: elective resections - ileoanal anastomosis - MC morbidity

A

leak is the MC major morbidity, can lead to sepsis, tx w drainage and abx

130
Q

UC: tx of infectious pouchitis

A

flagyl

131
Q

UC: cancer risk

A

1% per year startin 10 years after initial dx for pts w pancolitis …. cancer more evenly spread throughout the colon …. need yearly colonoscopy every 8-10 years after dx

132
Q

UC: extraintestinal manifestations - MC requiring total colectomy in kids

A

failure to thrive

133
Q

UC: extraintestinal manifestations - list those that do NOT get better with colectomy

A

primary sclerosing cholangitis, ankylosing spondylitis

134
Q

UC: extraintestinal manifestations - list those that DO get better with colectomy

A

most ocular problems, arthritis, anemia

135
Q

UC: extraintestinal manifestations - pyoderma gangrenosum cure rate and tx

A

50%, steroids

136
Q

UC: extraintestinal manifestations - complications

A

can get thromboembolic diseases

137
Q

HLA B27 assoc with that

A

sacroiliitis, ankylosing spondylitis, UC

138
Q

UC vs Crohn’s: transmural inflammation

A

seldom, common

139
Q

UC vs Crohn’s: granulomas

A

seldom, >50%

140
Q

UC vs Crohn’s: fissuring

A

rare, common

141
Q

UC vs Crohn’s: fibrosis

A

rare, common

142
Q

UC vs Crohn’s: submucosal inflammation

A

rare, common

143
Q

UC vs Crohn’s: crypt abscesses

A

common, uncommon

144
Q

UC vs Crohn’s: small bowel involvement

A

rare (backwash ileitis), common

145
Q

UC vs Crohn’s: anatomic location

A

continuous, skip

146
Q

UC vs Crohn’s: rectal involvement

A

common, may be spared

147
Q

UC vs Crohn’s: bleeding

A

common, absent

148
Q

UC vs Crohn’s: fistulas

A

rare, common

149
Q

UC vs Crohn’s: perianal disease

A

rare, common

150
Q

UC vs Crohn’s: ulcers

A

rare, common

151
Q

UC vs Crohn’s: surrounding mucosa

A

pseudopolyps, relatively normal

152
Q

UC vs Crohn’s: cobblestoning of mucosa

A

none, long-standing disease

153
Q

UC vs Crohn’s: mucosal friability

A

common, uncommon

154
Q

UC vs Crohn’s: vascular pattern

A

absent, normal

155
Q

UC vs Crohn’s: fat wrapping

A

rare, common

156
Q

carcinoid of colon and rectum: rate

A

15% of all carcinoids, infrequent cause of carcinoid syndrome

157
Q

carcinoid of colon and rectum: mets related to what

A

size of tumor

158
Q

carcinoid of colon and rectum: amnt w spread

A

2/3 w local or systemic spread

159
Q

carcinoid of colon and rectum: mgmt of low rectal carcinoids vs colon or high rectal

A

<2cm low rectal = wide local excision with negative margins …. >2cm low rectal or invasion of musc propria = APR …. colon or high recal = formal resection with adenectomy

160
Q

colonic obstruction: colon perf with obstruction

A

most likely to occur in cecum … law of LaPlace: tension = pressure x diameter

161
Q

colonic obstruction: closed loop obstruction

A

can be worrisome, can have rapid progression and perforation with minimal distention …. competent ileocecal valve can lead to closed loop obstruction

162
Q

colonic obstruction: causes

A

1 cancer, #2 diverticulitis

163
Q

colonic obstruction: pneumatosis intestinalis

A

air in bowel wall, assoc w ischemia and dissection of air through areas of bowel wall

164
Q

colonic obstruction: air in portal system

A

usually indicates significant infection or necrosis of large or small bowel, usually an ominous sign

165
Q

Ogilvie’s syndrome: describe

A

pseudoobstruction of colon

166
Q

Ogilvie’s syndrome: assoc with what

A

opiate use, bedridden or older patients, recent surgery, infection, trauma

167
Q

Ogilvie’s syndrome: complications

A

massive dilated colon which can perforate

168
Q

Ogilvie’s syndrome: tx

A

check and replete electrolytes (esp K), discontinue drugs that slow the gut (i.e. morphine), NGT … if colon >10cm - high risk of perforation —> decompression with colonoscopy and neostigmine … cecostomy if that fails

169
Q

amoebic colitis: organism, source

A

entamoeba histolytica … from contaminated food and water with feces that contain cysts

170
Q

amoebic colitis: primary vs secondary infection

A

primary - in colon … secondary - in liver

171
Q

amoebic colitis: risk factors

A

travel to mexico, etoh, fecal-oral transmission

172
Q

amoebic colitis: sx

A

similar to UC (dysentery), chronic more common form (3-4 bowel movements per day, cramping, fever)

173
Q

amoebic colitis: dx

A

endoscopy —> ulceration, trophozoites … 90% w anti-amebic Ab

174
Q

amoebic colitis: tx

A

flagyl, diiodohydroxyquin

175
Q

actinomyces: px

A

can present as mass, abscess, fistula, induration

176
Q

actinomyces: types

A

suppurative, granulomatous

177
Q

actinomyces: MC site

A

cecum (can be confused w cecal CA)

178
Q

actinomyces: pathology

A

shows yellow-white sulfur granules

179
Q

actinomyces: tx

A

penicillin or tetrocycline, drainage of any abscess

180
Q

diverticula: describe / pathophys

A

herniation of mucosa through colon wall sites where arteries enter the muscular wall … circular muscle thickens adjacent to diverticulum with luminal narrowing …. caused by straining which increases intraluminal pressure

181
Q

diverticula: more likely to present on which side? bleeding occurs on which side?

A

L side (80%) in the sigmoid colon …. R sided, 50% of bleeds occur on R (but L is more common overall)

182
Q

diverticula: %

A

35% of population

183
Q

lower GI bleeding: +stool guaiac

A

can be positive for 3 weeks after bleed

184
Q

lower GI bleeding: hematemesis

A

bleeding anywhere from pharynx to ligament of Trietz

185
Q

lower GI bleeding: melena

A

passage of tarry stools, need as little as 50cc

186
Q

lower GI bleeding: azotemia after GI bleed

A

caused by production of urea from bacterial action on intraluminal blood (inc BUN and t bili)

187
Q

lower GI bleeding: sensitivity w arteriography vs RBC scan

A

bleeding must be >= 0.5cc/min vs >= 0.1cc/min

188
Q

lower GI bleeding: workup

A

NGT to r/o UGI source, proctoscopy to r/o recal source –> see continued massive hemorrhage vs low rate of intermittent hemorrhage

massive —> angiography —> either diagnostic or nondiagnostic

low rate or intermittent hemorrhage —> colonoscopy —> diagnostic vs if non diagnostic then get RBC scan, enterolysis, RBC scan

189
Q

diverticulitis: pathophys

A

mucosal perforation in diverticulum with adjacent fecal contamination … denotes infection and inflammation of the colonic wall as well as surrounding tissue

190
Q

diverticulitis: px

A

LLQ pain, tenderness, fever, inc WBCs

191
Q

diverticulitis: dx

A

CT scan is needed only if worried about complications of disease

192
Q

diverticulitis: follow up

A

need follow up colonoscopy after an episode of diverticulitis to r/o colorectal cancer

193
Q

diverticulitis: most significant complication

A

abscess formation, can usually perc drain

194
Q

diverticulitis: signs of complication

A

obstruction, sx, fluctuant mass, peritoneal signs, temp >39, WBCs >20

195
Q

diverticulitis: tx of uncomplicated diverticulitis

A

levofloxacin and flagyl, bowel rest x3-4 days, mild cases an be treated as outpatient

196
Q

diverticulitis: surgical indications

A

significant complications (i.e. total obstruction not resolved with medical therapy, perforation, or abscess formation not amenable to perc drainage)

197
Q

diverticulitis: surgical approach

A

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

198
Q

diverticulitis: R sided diverticulitis dx and mgmt

A

80% discovered at the time of incision for appendectomy …. tx w R hemicolectomy

199
Q

diverticulitis: colovesicular fistula - px

A

fecaluria, pneumouria

200
Q

diverticulitis: colovesicular fistula - MC pts

A

occurs in M, F are more likely to get colovaginal fistula

201
Q

diverticulitis: colovesicular fistula - best diagnostic test

A

cystoscopy

202
Q

diverticulitis: colovesicular fistula - tx

A

close bladder opening, resect involved segment of colon, perform re-anastomosis, diverting ileostomy, interpose omentum between the bladder and colon

203
Q

MC cause of lower GI bleed

A

diverticulosis

204
Q

diverticulosis bleeding: amnt

A

usually significant

205
Q

diverticulosis bleeding: % stop spontaneously vs recurrence

A

75% stop spontaneously vs 25% recurs

206
Q

diverticulosis bleeding: caused by which vessels

A

disrupted vasa rectum, creates arterial bleeding

207
Q

diverticulosis bleeding: dx

A

NGT to r/o UGI bleed …. colonoscopy usually 1st step –> can be therapeutic (place hemo-clips) and can localize bleed if surgery needed …. angio 1st if massive bleeding (hypotension, tachy) - want to localize area for surgery, may be able to treat at angio with highly selective coil embolization … OR if hypotensive and not responding to resuscitation —> colectomy at site of bleeding if identified or subtotal colectomy if no source identified … tagged RBC scan for intermittent bleeds that are hard to localize

208
Q

diverticulosis bleeding: tx

A

colonoscopy can ligate bleeding …. arteriography - can use vasopressin (to temporize) or highly selective coil embolization, also demonstrates where the bleed is should surgery be required …. may need segmental colectomy or possible subtotal colectomy if bleeding is not localized and controlled

209
Q

diverticulosis bleeding: mgmt of recurrent diverticular bleed

A

resection of that area

210
Q

angiodysplasia bleeding: location

A

more common on R side

211
Q

angiodysplasia bleeding: bleeding compared to diverticular

A

angiodysplasia is less severe but more likely to recur (80%)

212
Q

angiodysplasia bleeding: causes what type of bleeding

A

venous

213
Q

angiodysplasia bleeding: soft signs on angiogram

A

tufts, slow emptying

214
Q

angiodysplasia bleeding: % with aortic stenosis

A

20%, usually gets better after valve replacement

215
Q

ischemic colitis: sx

A

abdominal pain, bright red bleeding

216
Q

ischemic colitis: causes

A

low-flow state (i.e. recent MI, CHF), ligation of the IMA intra-op (i.e. AAA repair), embolus or thrombosis of IMA, sepsis

217
Q

ischemic colitis: locations most vulnerable

A

most vulnerable until low-flow state …. splenic flexure and upper rectum …. splenic flexure = Griffith’s point = SMA and IMA junction …. Sudeck’s point = superior rectal and middle rectal artery junction

218
Q

ischemic colitis: dx

A

CT scan or endoscopy —> cyanotic edematous mucosa covered with exudates ….. lower 2/3 of the rectum is spared —> supplied by the middle and inferior rectal arteries (off internal iliacs) …. if gangrenous colitis is suspected (peritonitis), NO colonoscopy, instead go straight to OR for sigmoid resection or L hemicolectomy

219
Q

pseudomembranous colitis: organisms

A

C difficile

220
Q

pseudomembranous colitis: sx

A

watery, green, mucoid diarrhea, pain and cramping

221
Q

pseudomembranous colitis: when does it occur?

A

up to 3 weeks after abx, increased in postop, elderly, and ICU patients

222
Q

pseudomembranous colitis: carrier state

A

not eradicated, 15% recurrence

223
Q

pseudomembranous colitis: key findings

A

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

224
Q

pseudomembranous colitis: MC site

A

distal colon

225
Q

pseudomembranous colitis: dx

A

C diff toxin

226
Q

pseudomembranous colitis: tx

A

oral - vanc or flagyl … IV - flagyl … lactobacillus can also help, stop other abx or change them

227
Q

neutropenic typhlitis: aka

A

enterocolitis

228
Q

neutropenic typhlitis: presentation and tx

A

follows chemo when WBCs are low (nadir), can mimic surgical disease, can often see pneumatosis intestinalis (NOT surgical indication in this case) … tx = abx, pts will improve when WBCs increase, surgery ONLY for free perforation

229
Q

infectious causes of colitis

A

salmonella, shigella, campylobacter, CMV, Yersinia (can mimic appendicitis inkids), other viral infections, Giardia

230
Q

Yersinia: px, source, tx

A

can mimic appendicitis, comes from contaminated food (feces, urine), tx w bactrim or tetracycline

231
Q

megacolon: inc risk for what?

A

volvulus, enlargement is proximal to non-peristalsing bowel

232
Q

megacolon: causes

A

hirschsprung’s, trypanosoma cruzi

233
Q

Hirschsprung’s disease: MC area, dx

A

megacolon, rectosigmoid is most common, dx is rectal bx

234
Q

Trypanosoma cruzi

A

MC acquired cause of megacolon, 2/2 destruction of nerves

235
Q

Mut Y Homolog associated polyposis

A

AR: Right sided colonic polyps, MYH gene mutation. less polyps than FAP

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