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Flashcards in Colon and Appendix Deck (138)
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1
Q

colonoscopy is limited by occassional failure to reach the

A

right colon

2
Q

large intestine is composed of

A

cecum, appendix, colon, rectum and anal canal

3
Q

total length of LI

A

1.5 m

4
Q

LI is characterized by

A

taenia coli, 3 longitudinal bands of muscle that traverse the colon shortening it to form the haustra, the sacculations created by puckering of bowel wall

5
Q

major functions of LI

A

formation, transport, evacuation of feces

6
Q

part of LI that absorb water

A

cecum, ascending colon

7
Q

large blind pouch that extends below the level of the ileocecal valve

A

cecum

8
Q

cecum lies in the ____ but may be quite mobile

A

right iliac fossa

9
Q

cecum is intraperitoneal or extraperitoneal?

A

usually covered on all sides by peritoneum (intraperitoneal), but may be fixed extraperitoneall, covered only on its ventral surface by peritoneum

10
Q

worm-like tube that hangs from near the apex of cecum

A

appendix

11
Q

consists of 2 lips that project into the cecum forming a sometimes prominent mass

A

ileocecal valve

12
Q

ascending colon is intraperitoneal or extraperitoneal

A

extraperitoneal, lying in the anterior pararenal space, covered only on its ventral surface by peritoneum

13
Q

curve of hepatic flexure that is closely related to the descending duodenum and right kidney

A

proximal more posterior curve

14
Q

hepatic flexure curve that is closely related to the gallbladder

A

distal anterior curve

15
Q

transverse colon is intraperitoneal or extraperitoneal

A

intraperitoneal and suspended from the transverse mesocolon

16
Q

limits the superior extent of the small bowel loops

A

transverse mesocolon

17
Q

closely related to the tail of the pancreas and caudal aspect of the spleen

A

splenic flexure

18
Q

splenic flexure is anchored to the diagphragm by

A

phrenicocolic ligament

19
Q

serves as the boundary between processes of the left subphrenic space and left paracolic gutter

A

splenic flexure

20
Q

descending colon is intraperitoneal or extraperitoneal

A

extraperitoneal, within the anterior pararenal space and is covered by peritoneum only on its ventral space

21
Q

forms a redundant loop of variable length from the distal ascending colon in the left iliac fossa to the rectum

A

sigmoid colon

22
Q

sigmoid colon is intraperitoneal or extraperitoneal

A

completely intraperitoneal and is suspended by sigmoid mesocolon that allows considerable mobility

23
Q

sigmoid colon penetrates the peritoneum at the level of ____ to continue as the extraperitoneal rectum

A

S2 to S4

24
Q

rectum extends for approximately ___ cm in close relationship with the sacrum

A

12 cm

25
Q

peritoneum forming the pouch of Douglas covers the ____ and _____ aspects of rectum

A

ventral and lateral aspects

26
Q

length of anal canal is ___ cm and is invested by the sphincter ani and levator ani muscles

A

3 to 4 cm long

27
Q

a series of vertical folds form the _______, beneath which are the veins that when dilated are hemorrhoids

A

rectal columns of Morgagni

28
Q

thickness of the wall of the normal colon does not exceed __ mm

A

5 mm

29
Q

generic term for a lesion that protrudes from the mucosal surface of the GI tract

A

polyps

30
Q

approximately 50% of colorectal adenocarcinoma occur in the

A

rectum and rectosigmoid area

31
Q

approximately 25% of colorectal adenocarcinoma arise from

A

sigmoid colon

32
Q

Most colorectal adenocarcinoma are what form and size

A

constricting annular lesion, 2 to 6 cm in diamter, with raised everted edges and ulcerated mucosa

33
Q

nearly all cancers of the colon arise from

A

pre-existing adenomas

34
Q

infiltrating scirrhous adenocarcinoma tumors are common in

A

gastric carcinoma

35
Q

infiltrating scirrhous adenocarcinoma when seen in the LI, is associated with

A

ulcerative colitis

36
Q

most frequent complication of colorectal adenocarcinoma

A

obstruction

37
Q

conditions with increased risk of colorectal adenocarcinoma

A

ulcerative colitis, crohn disease, familial adenomatpus polyposis syndrome, Peutz-Jeghers syndrome

38
Q

Bowler hats sign is seen in

A

polyps, when viewed obliquely

39
Q

imaging technique that shows improved detection of lymph node metastases in colorectal adenocarcinoma

A

Diffusion weighted MR

40
Q

indicative of tumor extension through the bowel wall

A

pericolonic fat stranding

41
Q

size of LN enlargement denoting lymphatic spread of tumor

A

> 1 cm

42
Q

major indication of colonoscopy and imaging studies of the colon

A

detection of colon polyps

43
Q

rules of thumb in polyps at risk of malignancy

A

polyps less than 5 mm are almost all hyperplastic, with a risk of malignancy less than 0.5%, polyps 5 to 10 mm size are 90% adenomas, with a risk of malignancy of 1 %. Polyps 10 to 20 mm in size are usually adenomas, with a risk of malignancy of 10%. polyps larger than 20 mm are 50% malignant

44
Q

polyps that are nonneoplastic mucosal proliferation. they are round and sessile. nearly all are less than 5 mm in size

A

Hyperplastic polyps

45
Q

polyps that are distinctly premalignant and a major risk for development of colorectal carcinoma. they are neoplasms with a core of connective tissue

A

adenomatous polyps

46
Q

at what age does approximately 5-10% of population have adenomatous polyps

A

older than 40 years

47
Q

polyps that represent 1% of colon polyps. they are a common cause of rectal bleeding in children

A

hamartomatous polyp

48
Q

Peutz-Jeghers polyp is a type of

A

hamartomatous polyp

49
Q

polyps that are usually multiple, and associated with inflammatory bowel disease

A

inflammatory polyps

50
Q

inheritance pattern of familial adenomatous polyposis syndrome

A

autosomal dominant with high penetrance

51
Q

how many of FAPS are inherited and what portion of the cases are spontaneous

A

2/3 inherited, 1/3 spontaneous

52
Q

polyps in FAPS are ____ which are usually evident by age 20

A

tubulovillous adenomas

53
Q

recommended therapy for FAPS

A

total colectomy with rectal mucosectomy and ileoanal pouch construction due to high risk for colorectal cancer

54
Q

patients with FAPS are at risk of numerous extracolonic manifestations such as

A

carcinomas of the small bowel, thyroid carcinoma, mesenteric fibromatosis

55
Q

FAPS patient with associated bone and skin abnormalities including cortical thickening of the ribs and long bones, osteomas of the skull, supernumerary teeth, exostoses of mandible and dermal fibromas, desmoids and epidermal inclusion cysts have been diagnosed as

A

Gardner syndrome

56
Q

FAPS patients with associated tumors of the CNS have been grouped as

A

Turcot syndrome

57
Q

nonneoplastic growths with a smooth muscle core covered by mature glandular epithelihm . they carry no risk of malignant transformation, however, they may develop adenomatous polyps which do carry a risk of malignancy

A

hamatomatous polyps

58
Q

hamartomatous polyps that is an autosomal dominant condition, predominantly involving the small bowel, associated with dark pigmented spots on skin and mucous membranes are characteristic

A

Peutz-jeghers syndrome

59
Q

syndrome of multiple hamartomas including hamartomatous polyposis of GI tract, with goiter and thyroid adenomas and increased risk of breast cancer and transitional cell carcinoma of the urinary tract. all patietns have mucocutaneoys lesions with facial papules, oral papillomas and palmoplantar keratoses

A

Cowden disease

60
Q

disease of older patients with a mean age of onset of 60 years. polyps are distributed throughout the stomach, small bowel and colon. associated findings include nail atrophy, brownish skin pigmentation, and alopecia. patients present with watery diarrhea and protein-losing enteropathy

A

Cronkhite-Canada syndrome

61
Q

lymphoma in the colon is less common. if present, what cell type

A

non-Hodgkin B-cell lymphoma

62
Q

most common submucosal tumor of colon

A

lipomas

63
Q

colonic lipomas are frequent in the

A

cecum and ascending colon

64
Q

endometriosis commonly implants on the

A

sigmoid colon and rectum, within the cul-de-sac

65
Q

common idiopathic inflammatory disease involving primarily the mucosa and submucosa of colon. disease consists of ulcerations, edema and hyperemia

A

ulcerative colitis

66
Q

peak age of onset of UC

A

20 to 40 years and age after 50

67
Q

radiographic hallmarks of UC

A

granular mucosa, confluent shallow ulcerations, symmetry of disease around the lumen, and continious confluent diffuse involvement

68
Q

deeper ulcerations of thickened edematous mucosa with crypt abscesses extending in the submucosa

A

collar button ulcers

69
Q

mucosal remnants in areas of extensive ulceration

A

pseudopolyps

70
Q

small islands of inflamed mucosa

A

inflammatory polyps

71
Q

mucosal tags that are seen in quiescent phases of the disease

A

postinflammatory polyps

72
Q

postinflammatory polyps with a characteristic worm-like appearance. they are seen in an otherwise normal appearing colon

A

Filiform polyps

73
Q

polyps that may occur during healing after mucosal injury

A

hyperplastic polyps

74
Q

involvement in UC

A

extend from rectum proximally in a symmetric and continuous pattern. terminal ileum is nearly always normal

75
Q

may produce an ulcerated but patulous terminal ileum

A

rare backwash ileitis

76
Q

complications of UC

A

strictures, usually 2 to 3 cm or more in length and commonly involving the transverse colon and rectum, colorectal adenocarcinoma, toxic megacolon, massive hemorrhage

77
Q

CT findings in UC

A

wall thickening, with halo sign of low density submucosal edema, narrowing of the lumen of colon, pseudopolyps, pneumatosis coli with megacolon

78
Q

associated extraintestinal diseases of UC

A

sacroilitis, mimicking ankylosing spondylitis, uveitis and iritis, cholangitis, thromboembolic disease

79
Q

features of UC

A

circumferential disease, regional/continuous disease, symmetric disease, predominantly left-sided, rectum nearly always present, confluent shallow ulcers, no aphthous ulcrs, collar button ulcers, small bowel not involved except for terminal ileum, terminal ileum usually normal, terminal ileum patulous, ileocecal valve open, no pseudodiverticula, no fistulae, hight risk of cancer, risk of toxic megacolon

80
Q

features of crohn colitis

A

eccentric disease, skip lesions/discontinuous disease, asymmetric disease, predominantly right-sided, rectum normal in 50%, confluent deep ulcers, aphthous ulcers early, transverse and longitudinal ulcers, involves any small bowel segments, terminal ileum usually diseased, terminal ileum narrowed, ileocecal valve stenosed, pseudodiverticula, fistulae common, low risk of cancer, low risk of toxic megacolon

81
Q

collar button ulcers is found in

A

UC

82
Q

formed by asymmetric fibrosis on one side of the lumen, causing saccular outpouches on the other side

A

pseudodiverticula

83
Q

a potentially fatal condition characterized by marked colonic distention and risk of perforation

A

toxic megacolon

84
Q

caused by a variety of bacteria (Salmonella, Shigella, E.coli) parasites, viruses (CMV, herpes) and fungi (histoplasmosis, mucormycosis). most cause pancolitis with edema, and inflammatory wall thickening with infiltration of pericolonic fat

A

infectious colitis

85
Q

occurs as a complications of UC, crohn disease, pseudomembranous colitis, use of antidiarrheal drugs and hypokalemia

A

toxic megacolon

86
Q

radiographic findings of toxic megacolon

A

marked dilation of the colon (transverse colon > 6 cm) with absence of haustral markings, edema and thickening of the colon wall , pneumatosis coli, evidence of perforation

87
Q

inflammatory disease of the colon and occassionally involving the small bowel, characterized by the presence of a pseudomembrane of necrotic debris and overgrowth of clostridium difficile

A

pseudomembranous colitis

88
Q

what contributes to pseudomembranous colitis

A

antibiotics (any that change bowel flora), intestinal ischemia (especially following surgery), irradiation, long term steroids, shock, and colonic obstruction

89
Q

CT findings of pseudomembranous colitis

A

marked wall thickening up to 30 mm (average 15 mm), with halo or target appearance, characteristic stripes of intrauminal contrast media trapped between nodular areas of wall thickening , mild pericolonic fat inflammation disproportionate with the marked colonic wall inflammation and ascites

90
Q

characteristic stripes of intraluminal contrast media trapped between nodular areas of wall thickening in pseudomembranous colitis is called

A

accordion sign

91
Q

pathophysiology of amebic colitis

A

encysted amoebae are ingested with contaminated food and water. the cyst capsule is dissolved in the SI, releasing trophozoites that migrate to the colon and burrow into the mucosa, forming small abscesses. can spread throughout the body by hematogeneous embolization or direct invasion

92
Q

colitis that produces dysentery with frequent bloody mucoid stools. it demonstrates a disease that closely mimics crohn colitis with aphthtous ulcers, deep ulcers, asymmetric disease and skip areas

A

amebic colitis

93
Q

primary sites of amebic colitis

A

cecum and rectum

94
Q

what part of GI tract is characteristically not involved in amebic colitis

A

terminal ileum

95
Q

potentially fatal infection of the cecum and ascending colon usually seen in patients who are neutropenic and immunocompromised by chemotherapy

A

Typhilitis (neutropenic colitis)

96
Q

concentric, often marked, thickening of the wall of the cecum and ascending colon with prominent pericolonic inflammatory changes are characteristic. patients are also at risk for colon ischemia

A

typhilitis

97
Q

mimics UC and crohn colitis both clinically and radiographically. causes include arterial occlusion caused by atherosclerosis, vasculitis, arterial emboli; venous thrombosis due to neoplasm, oral contraceptives, hypercoagulation conditions and low flow states such as hypotension, CHF and cardiac arrythmias

A

Ischemic colitis

98
Q

sma supplies the

A

right colon from the cecum to splenic flexure

99
Q

ima supplies the

A

left colon from the splenic flexure to the rectum

100
Q

watershed areas in colon that is most susceptible to ischemic colitis

A

splenic flexure region and descending colon

101
Q

early changes of ischemic colitis

A

thickening of the colon wall, spasm, spiculation

102
Q

in ischemic colitis, as blood and edema accumulate within the bowel wall, multiple nodular defects are produced in a pattern called

A

thumbprinting

103
Q

submucosal edema may produce a low-density ring bordering on the lumen which is called what sign

A

target sign

104
Q

highly suggestive of ischemia

A

pneumatosis

105
Q

AIDS associated colitis happens with CD4 count of

A

below 200

106
Q

causative agents in AIDS associated colitis

A

CMV and cryptosporidosis

107
Q

what part of colon is commonly affected by AIDS associated colitis

A

right colon

108
Q

most commonly involved in radiation colitisdue to radiation of pelvic malignancy

A

rectosigmoid region

109
Q

radiation colitis is produced by

A

slowly progressive endarteritis that causes ischemia and fibrosis

110
Q

colitis that is due to chronic irritation of the mucosa by laxatives including castor oil, bisacodyl and senna. the involved colon may be dilated and without haustra or narrowed. right colon is most commonly affected. bizzare contractions are often observed

A

cathartic colon

111
Q

finding that is characteristic of epiploic appendigitis, which presents as inflammation surrounding central fat

A

ring sign

112
Q

cause of abdominal pain that may mimic appendigitis, diverticulitis and colitis

A

epiploic appendagitis

113
Q

these are pedunculated fatty structures that occur in rows on the external aspect of the colon, adjacent to the anterior and posterior taenia coli

A

epiploic appendages

114
Q

epiploic appendages are in greatest concentration in the

A

cecum and sigmoid colon sparing the rectum

115
Q

caused by ischemic infarction of epiploic appendages, often resulting from torsion

A

epiploic appendagitis

116
Q

CT findings in epiploic appendagitis

A

presents as 1 to 4 cm ovoid mass with central fat density and surrounding inflammation abutting the wall of colon, hyperdense enhancing rim surrounds the mass “ring sign”, inflammatory changes may extend into the adjacent peritoneum, a central high attenuation dot is often presenting the central thrombosed vessels, infarcted tissue may calcify

117
Q

acquired condition in which the mucosa and muscularis mucosae herniate through the muscularis propria of the colon wall, producing a saccular outpouching

A

colon diverticulosis

118
Q

classified as false diverticula because the sacs lack all of the elements of the normal colon wall

A

colon diverticulosis

119
Q

age predilection of colon diverticulosis

A

rare under age 25, increases with age thereafter to affect 50% of the population over age 75

120
Q

major risk factor for diverticulosis

A

low residue diet

121
Q

cause of painless colonic bleeding that may be brisk and life threatening

A

diverticulosis without diverticulitis

122
Q

complications of diverticulitis include

A

bowel obstruction, bleeding, peritonitis and sinus tract and fistula formation

123
Q

obstruction due to diverticulitis is often temporarily relieved

A

by smooth muscle relaxants such as glucagon

124
Q

fistulas from acute diverticulitis are common to the

A

bladder, vagina, skin, but may develop to any lower abdominal organ including fallopian tubes, small bowel and other parts of the colon

125
Q

CT findings of localized wall thickening, inflammation of pericolonic fat, pericolonic abscess, diverticula at or near the site of inflammation and common involvement of the adnexa with fluid collections and fistulae

A

acute diverticulitis

126
Q

screening examination of choice for confirming the presence of and often localizing lower GI bleeding in acute diverticulitis

A

Radionuclide imaging studies

127
Q

capable of detecting bleeding at rates below 0.1 ml/min

A

Technetium-99m sulfur colloid or Tc-99m-red blood cell studies

128
Q

refers to ectasia and kinking of mucosal and submucosal veins of the colon wall. condition results from a chronic intermittent obstruction of the veins where they penetrate the circular muscle layer

A

angiodysplasia

129
Q

appendix arises from the

A

posteromedial aspect of the cecum at the junction of the taenia coli, approximately 1-2 cm from the ileocecal valve

130
Q

blind-ended tube that is 4 to 5 mm in diameter and approximately 8 cm in length, altho it may be up to 30 cm long

A

appendix

131
Q

formed by calcium deposition around a nidus of inspissated feces

A

appendicolith

132
Q

normal diameter of appendix when compressed

A

less than 6 mm

133
Q

CT is the usual imaging method of choice for acute appendicitis in

A

men, older patients and when periappendiceal abscess is suspected

134
Q

distention of all portion of the appendix with sterile mucus

A

mucocele

135
Q

appendiceal dilation greater than ___ mm suggests possible mucocele

A

13 mm

136
Q

rupture of the mucocel may result in

A

pseudomyxoma peritonei

137
Q

most common tumor of appendix, accounting for 85% of all tumors

A

carcinoid

138
Q

most common location for carcinoid tumor

A

appendix