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1
Q

intestine: nutrient and water absorption

A

small intestine

2
Q

intestine: water absorption

A

large intestine

3
Q

portions of the duodenum

A
  • bulb (1st portion) - 90% of ulcers here
  • descending (2nd) - contains ampulla of Vater (duct of wirsung) and duct of santorini
  • transverse (3rd)
  • ascending (4th)
4
Q

portions of the duodenum that are retroperitoneal

A

descending and transverse portions

5
Q

transition point of the 3rd and 4th portions of the duodenum

A

acute angle between the aorta (posterior) and SMA (anterior)

6
Q

vascular supply duodenum

A

superior (off gastroduodenal artery) and inferior (off SMA) pancreaticoduodenal arteries

  • both have anterior and posterior branches
  • many communications between these arteries
7
Q

100 cm long; long vasa recta, circular muscle folds

  • absorbs 95% NaCl and 90% water
  • vascular supply: SMA
A

Jejunum

8
Q

maximum site of all absorption except for b12 (terminal ileum), bile acids (ileum - non conjugated; terminal ileum - conjugated), iron (duodenum) and folate (terminal ileum)

A

jejunum

9
Q

150 cm long, short vasa recta, flat

- vascular supply: sma

A

ileum

10
Q

what is absorbed at the intestinal brush border?

A

maltase, sucrase, limit dextrinase, lactase

11
Q

normal sizes: small bowel / transverse colon / cecum

A

3 / 6 / 9 cm

12
Q

SMA eventually branches into the…

A

ileocolic artery

13
Q

cell types of the small intestine

A

absorptive cells, goblet cells (mucin secretion), paneth cells (secretory granules, enzymes), enterochromaffin cells, runner’s glands, peyer’s patches, m cells

14
Q

What do goblet cells secrete?

A

mucin secretion

15
Q

What do paneth cells secrete?

A

secretory granules, enzymes

16
Q

What do enterochromaffin cells secrete?

A

APUD, 5-hydroxytryptamine release, carcinoid precursor

17
Q

What do brunner’s cells secrete?

A

alkaline solution

18
Q

What do M cells secrete?

A

antigen-presenting cells in intestinal wall

19
Q

released into the gut; also in mother’s milk

A

IgA

20
Q

small bowel has both heme and Fe transporters

A

Fe

21
Q

where is iron absorbed?

A

duodenum

22
Q

where is folate absorbed?

A

terminal ileum

23
Q

where is b12 absorbed?

A

terminal ileum

24
Q

where are bile acids absorbed?

A
  • ileum: non conjugated

- terminal ileum: conjugated

25
Q

what are the phases of migrating motor complex (gut motility)?

A

phase 1: rest

2: acceleration and gallbladder contraction
3: peristalsis
4: deceleration

26
Q

Most important hormone in migrating motor complex (Acts on phase 3)

A

motilin

27
Q

percent of bile salts reabsorbed

A

95%

28
Q

how are bile salts reabsorbed?

A
  • 50% passive absorption (non-conjguated bile salts) - 45% ileum, 5%
  • 50% active resorption (conjugated bile salts) in terminal ileum (Na/K ATPase); conjugated bile salts are absorbed only in the terminal ileum
29
Q

When do gallstones form?

A

gallstones form after terminal ileum resection from malabsorption of bile salts

30
Q

how is diagnosis of short-gut syndrome made?

A

symptoms; not length of bowel

31
Q

diarrhea, steatorrhea, weight loss, nutritional deficiency

- lose fat, B12, electrolytes, water

A

short-gut syndrome

32
Q

stains: checks for fecal fat

A

sudan red stain

33
Q

test: checks for b12 absorption (radiolabeled b12 in urine)

A

schilling test

34
Q

how much bowel do you need to survive off TPN?

A

75 cm to survive off TPN; 50 cm with competent ileocecal valve

35
Q

Tx: short gut syndrome

A

restrict fat, ppi to reduce acid, lomotil (diphenoxylate and atropine)

36
Q

causes of steatorrhea

A
  • gastric hyper secretion of acid

- interruption of bile salt resorption

37
Q

how does gastric hyper secretion of acid cause steatorrhea?

A

decreased pH-> increased intestinal motility; interferes with fat absorption

38
Q

how does interruption of bile salt resorption cause steatorrhea?

A

(eg terminal ileum resection) interferes with micelle formation and fat absorption

39
Q

Tx: steatorrhea

A

control diarrhea (lomotil); decrease oral intake, especially fats, pancreas, ppi

40
Q

causes of non healing fistulas

A

FRIENDS: fistulas, radiation, inflammatory bowel disease, epithelialization, neoplasm, distal obstruction, sepsis/infection

41
Q

characteristics of high-output fistulas

A
  • more likely with proximal bowel (duodenum or proximal jejunum)
  • less likely to close with conservative management
42
Q

colonic fistulas vs small bowel

- which are more likely to close?

A

colonic fistulas are more likely to close than those in small bowel

43
Q

nonhealing fistula: patients with persistent fever

A

need to check for abscess (fistulogram, abdominal CT, upper GI with small bowel follow through)

44
Q

treatment: fistulas

A

most fistulas are iatrogenic and treated conservatively first: NPO, TPN, skin protection (stoma appliance), octreotide

45
Q

how do most non healing fistulas close?

A

majority close spontaneously without surgery

46
Q

surgical options of non healing fistulas

A

resect bowel segment containing fistula and perform primary anastomosis

47
Q

MCC obstruction without previous surgery

A

Small bowel: hernia

Large bowel: cancer

48
Q

MCC obstruction with previous surgery

A

Small bowel: adhesions

Large bowel: cancer

49
Q
  • pain: intermittent, intense, colicky; often relieved with vomiting
  • vomiting: large volumes, bilious, frequent
  • tenderness: epigastric or periumbilical; quite mild unless strangulated
  • distention: absent
  • obstipation: may not be present
A

proximal small bowel obstruction (open loop)

50
Q
  • pain: intermittent to constant
  • vomiting: low volume and frequency; progressively feculent with time
  • tenderness: diffuse and progressive
  • distention: moderate to marked
  • obstipation: present
A

Distal small bowel obstruction (open loop)

51
Q
  • pain: progressive, intermittent constant; rapidly worsens
  • vomiting: may be prominent (reflex)
  • tenderness: diffuse, progressive
  • distention: often absent
  • obstipation: may not be present
A

small bowel obstruction (closed loop)

52
Q
  • pain: continuous
  • vomiting: intermittent, not prominent; feculent when present
  • tenderness: diffuse
  • distention: marked
  • obstipation: present
A

colon and rectum obstruction

53
Q

type of bowel obstruction with no distention

A

proximal small bowel (open loop)

54
Q

AXR: obstruction

A

air-fluid level, distended loops of small bowel, distal decompression

55
Q

tx: 3rd spacing of fluid into bowel lumen with obstruction

A

need aggressive fluid resuscitaiton

56
Q

why is there air with bowel obstruction?

A

from swallowed nitrogen

57
Q

tx: bowel obstruction

A

bowel rest, NGT, IVF, -> cures 80% of partial SBO, 40% of complete SBO

58
Q

obstruction: surgical indications

A

progressing pain, peritoneal signs, fever, increasing WBCs (all signs of strangulation or perforation), or failure to resolve

59
Q

small bowel obstruction from gallstone usually in the terminal ileum

A

gallstone ileus

60
Q

imaging: what do you see in gallstone ileus?

A

classically see air in the biliary tree in a patient with small bowel obstruction

61
Q

what causes gallstone ileus?

A

caused by a fistula between the gallbladder and second portion of duodenum

62
Q

tx: gallstone ileus

A

remove stone from terminal ileum

  • can leave gallbladder and fistula if patient too sick
  • if not too sick, perform cholecystectomy and close duodenum
63
Q

2 ft from ileocecal valve
2% of population
usually presents in 1st 2 years of life with bleeding; is a true diverticulum
- accounts for 50% of all painless lower GI bleeds in children

A

meckel’s diverticulum

64
Q

what causes meckel’s diverticulum?

A

caused by failure of closure of the omphalomesenteric duct

65
Q

most common tissue found in meckel’s (can cause diverticulitis)

A

pancreas tissue

66
Q

most likely to be symptomatic (bleeding most common) - tissue in meckel’s diverticulum

A

gastric mucosa

67
Q

two types of tissue in meckel’s diverticulum

A

pancreatic and gastric tissue

68
Q

adults: MC presentation of meckel’s diverticulum

A

obstruction

69
Q

when do you remove meckel’s diverticulum?

A

incidental -> usually not removed unless gastric mucosa suspected (diverticulum feels thick) or has a very narrow neck

70
Q

dx: meckel’s diverticulum

A

can get a meckel’s scan (99Tc) if having trouble localizing (mucosa lights up)

71
Q

Tx: meckel’s diverticulum

A

diverticulotomy for uncomplicated diverticulitis or bleeding
- Need segmental resection for complicated diverticulitis (e.g. perforation), neck has > 1/3 the diameter of the normal bowel lumen, or if diverticulitis involves the base

72
Q

what do you need to rule out in duodenal diverticula?

A

gallbladder-duodenal fistula

73
Q

primary management: duodenal diverticula

A

observation unless perforated, bleeding, causing obstruction, or highly symptomatic

74
Q

Frequency of duodenal diverticula

A

Duodenal > jejunal > ileal

75
Q

Tx: duodenal diverticula

A

Segmental resection if symptomatic.
- if juxta-ampullary usually can’t get resection and need choledochojejunostomy for biliary or ERCP with stent for pancreatitis symptoms (Avoid Whipple here)

76
Q

inflammatory bowel disease causing intermittent abdominal pain, diarrhea and weight loss; can also cause bowel obstructions and fistulas.
- 15-35 years old at 1st presentation; in Ashkenazi Jews

A

Crohn’s Disease

77
Q

portion of alimentary where crohn’s occurs

A

can occur anywhere from mouth to anus; usually spares rectum

78
Q

extraintestinal manifestations of crohn’s

A

arthritis, arthralgias, pyoderma gangrenosum, erythema nodosum, ocular diseases, growth failure, megaloblastic anemia from folate and vitamin b12 malabsorption.

79
Q

crohn’s: most commonly involved bowel segment

A

terminal ileum

80
Q

crohn’s: 1st presentation in 5%

A

anal / perianal disease

  • Tx: flagyl
  • anal disease most common symptom: large skin tags
81
Q

crohn’s disease: most common sites for initial presentation

A
  • terminal ileum and cecum: 40%
  • colon only: 35%
  • small bowel only: 20%
  • perianal: 5%
82
Q

Dx: crohn’s disease

A

colonoscopy with biopsies and enteroclysis can help make the diagnosis

83
Q

pathology: crohn’s disease

A

transmural involvement, segmental disease (skip lesions), cobblestoning, narrow deep ulcers, creeping fat, fistulas

84
Q

medical treatment: crohn’s

A

5-ASA and loperamide for maintenance; steroids for acute flares
- remicade (infliximab; TNF-alpha inhibitor) - for fistulas or steroid-resistant disease

85
Q

crohn’s: agents affecting natural course of disease

A

no agents affect natural course of disease

86
Q

may induce remission and fistula closure with small bowel crohn’s disease

A

TPN

87
Q

percent of patient needing operation in crohn’s

A

90%

88
Q

surgical indications: crohn’s disease

A
obstruction
abscess
megacolon
hemorrhage
blind loop obstruction
fissures
fistulas: enterocutnaeous, perineal, anarectovaginal
89
Q

margins in crohn’s surgery

A

do not need clear margins; just get 2cm away from gross disease with surgery

90
Q

obstruction: crohn’s

A

often partial and can be initially treated conservatively

91
Q

abscess: crohn’s

A

usually treated with percutaneous drainage

92
Q

megacolon: crohn’s

A

perforations occurs in 15%; usually contained

93
Q

hemorrhage: crohn’s

A

unusual in crohn’s but can occur

94
Q

blind loop obstruction: crohn’s

A

need resection

95
Q

fissures: crohn’s

A

no lateral internal sphincteroplasty in patients with crohn’s disease

96
Q

enterocutaneous fistula: crohn’s

A

can usually be treated conservatively

97
Q

perineal fistula: crohn’s

A

unroof and rule out abscess; let heal on its own

98
Q

anorectovaginal fistula: crohn’s

A

may need rectal advancement flap; possible colostomy

99
Q

chron’s: management of patients with diffuse disease of colon

A

proctocolectomy and ileostomy the procedures of choice (no pouches or ilio-anal anastomosis with crohn’s)

100
Q

tx: incidental finding of IBD in patient with presumed appendicitis who has normal appendix

A

remove appendix is cecum not involved (avoids future confounding diagnosis)

101
Q

crohn’s:

  • consider if patient has multiple bowel strictures to save bowel length
  • probably not good for patient’s 1st operation as it leaves disease behind
A

stricturoplasty (longitudinal incision through stricture, close transversely)

102
Q

complications of stricturoplasty

A

10% leakage/abscess/fistula rate with stricturoplasty (all of which can usually be treated conservatively)

103
Q

recurrence rate requiring surgery for Crohn’s disease after resection

A

50% recurrence rate

104
Q

chron’s: complications from removal of terminal ileum

A
  • decreased b12 uptake can result in megaloblastic anemia
  • decreased bile salt uptake causes osmotic diarrhea (bile salts) and steatorrhea (fat) in colon
  • decreased oxalate binding (calcium oxalate kidney stones - hyperoxaluria)
  • gallstones
105
Q

chron’s: mechanisms of megaloblastic anemia

A

decreased b12 uptake

106
Q

crohn’s: mechanism of osmotic diarrhea and steatorrhea

A

decreased bile salt uptake

107
Q

crohn’s: mechanism of hyperoxaluria (calcium oxalate kidney stones)

A

decreased oxalate binding to calcium secondary to increased intraluminal fat (fat binds Ca) -> oxalate then gets absorbed in the colon -> released in urine -> calcium oxalate kidney stones

108
Q

crohns: mechanism of gallstones

A

can form after terminal ileum resection from malabsorption of bile salts

109
Q

what produces serotonin in carcinoid?

A

kulchitsky cells (enterochromaffin cell or argentaffin cell)

110
Q

what is serotonin (carcinoid) a part of?

A

part of amine precursor uptake decarboxylase system (APUD)

111
Q

breakdown product of serotonin - can measure this in urine

A

5-hiaa

112
Q

what does carcinoid tumor release?

A

serotonin

bradykinin

113
Q

carcinoid: caused by bulky liver metastases

A

carcinoid syndrome (intermittent flushing - kallikrein ; diarrhea - serotonin)

114
Q

hallmark symptoms of carcinoid syndrome

A
intermittent flushing (kallikrein)
diarrhea (Serotonin)
  • can also get asthma-type symptoms (bradykinin) and right heart valve lesions
115
Q

what do you think about: if patient has carcinoid syndrome with small bowel carcinoid primary

A

it indicates metastasis to liver (liver usually clears serotonin)

116
Q

carcinoid syndrome: what do you do if you perform resection of liver metastases

A

perform cholecystectomy in case of future embolization

117
Q

carcinoid: best for localizing tumor not seen on ct scan

A

octreotide

118
Q

highest sensitivity for detecting a carcinoid tumor

A

chromogranin a level

119
Q

most common site for carcinoid tumor (50% of carcinoids arise here)

A

appendix carcinoid (ileum and rectum next most common)

120
Q

carcinoid: site where patients are at increased risk for multiple primaries and second unrelated malignancies

A

small bowel carcinoid

121
Q

tx: carcinoid in appendix

- 2cm or involving base

A
  • 2 cm or involving base: right hemicolectomy
122
Q

tx: carcinoid anywhere else in GI tract aside from appendix

A

treat like cancer (segmental resection with lymphadenectomy)

123
Q

chemotherapy for carcinoid

A

streptozocin and 5FU; usually just for unresectable disease

124
Q

useful for carcinoid syndrome palliation

A

octreotide

125
Q

carcinoid: tx for bronchospasm

A

aprotinin

126
Q

carcinoid: tx for flushing

A

alpha blockers (phenothiazine)

127
Q

what can cause false elevations in 5-hiaa?

A

fruits

128
Q

same colon CA risk as ulcerative colitis

A

crohn’s pancolitis

129
Q
  • can occur from small bowel or cecal tumors
  • most common presentation is obstruction
  • worrisome in adults as it often has a malignant lead point (i.e. cecal CA)

tx: resection

A

intussusception in adults

130
Q
  • most found in duodenum; present with bleeding, obstruction

- need resection when identified (often done with endoscope)

A

Adenomas - benign small bowel tumors

131
Q
  • autosomal dominant
  • hamartomas throughout GI tract (small and large bowel)
  • mucocutaneous melanotic skin pigmentation
  • pts have increased extra intestinal malignancies (mc- breast CA) and a small risk of GI malignancies
  • no prophylactic colectomy
A

Peutz-Jeghers syndrome

132
Q

mc extraintestinal malignancy in peutz-jeghers syndrome

A

breast cancer

133
Q

most common malignant small bowel tumor

A

adenocarcinoma (rare)

134
Q

where are most small bowel adenocarcinomas found?

A

high proportion are in the duodenum

135
Q

Symptoms of adenocarcinoma small bowel

A

obstruction, jaundice

136
Q

tx: small bowel adenocarcinoma

A

resection and adenectomy; Whipple if in 2nd portion of duodenum

137
Q

duodenal CA risk factors

A

FAP, Gardner’s, poylps, adenomas, von Recklinghausen’s

138
Q
  • usually in jejunum and ileum; most extraluminal

- hard to differentiate compared with leiomyoma (>5 mitoses/HPF, atypia, necrosis)

A

leiomyosarcoma

139
Q

what do you need to rule out in leiomyosarcoma?

A

make sure it is not a GIST (check for c-kit)

140
Q

tx: leiomyosarcoma in small bowel

A

resection; no adenectomy required

141
Q
  • usually in ileum; associated with Wegener’s, SLE, AIDS, Crohn’s, celiac sprue
  • usually NHL B cell type
  • Post transplantation: increased risk of bleeding and perforation
A

Lymphoma - malignant small bowel tumor

142
Q

dx: lymphoma - malignant small bowel

A

abdominal ct, node sampling

143
Q

tx: lymphoma - small bowel

A

malignancy: wide en block resection (include nodes) unless 1st or 2nd portion of the duodenum (chemo-XRT, no Whipple)

144
Q

survival rate small bowel lymphoma

A

40% 5 year survival rate

145
Q

highest incidence with colostomies; generally well tolerated and do not need repair unless symptomatic

A

parastomal hernias

146
Q

most common stomal infection

A

candida

147
Q

(hartmann’s pouch) - secondary to lack of short-chain fatty acids
- tx: short-chain fatty acids enemas

A

diversion colitis

148
Q

most common cause of stenosis of stoma

- tx: dilation if mild

A

ischemia

149
Q

most common cause of fistula near stoma site

A

crohn’s disease

150
Q

underneath stoma stie, often caused by irrigation device

A

abscesses

151
Q

increased in patients with ileostomy

A

gallstones and uric acid kidney stones

152
Q

1) anorexia
2) abdominal pain (periumbilical)
3) vomiting
- pain gradually migrates to the RLQ as peritonitis sets in
- most commonly occurs in patients 20-35 years
- patients can have normal WBC count

A

Appendicitis

153
Q

CT scan in appendicitis:

A
diameter > 7mm
wall thickness > 2mm (looks like a bull's eye)
fat stranding
no contrast in appendiceal lumen
try to give rectal contrast
154
Q

where is the appendix most likely to perforate?

A

midpoint of anti-mesenteric border

155
Q

mcc appendicitis in children; can follow a viral illness

A

hyperplasia

156
Q

mcc appendicitis in adults

A

fecalith

157
Q

what is the sequence of events in appendiceal luminal obstruction?

A

luminal obstruction is followed by distention of the appendix, venous congestion and thrombosis, ischemia, gangrene necrosis, and finally rupture

158
Q

appendicitis: nonoperative situtation

A

CT scan shows wall-offed perforated appendix (usually in elderly)
- TX: pecutaneous drainage and interval appendectomy at later date as long as symptoms are improving.

159
Q

follow up: nonoperative appendicitis (walled-off perforated appendix)

A

consider follow-up barium enema or colonoscopy to rule out perforated cecal colon CA

160
Q

why do children and elderly have higher propensity for appendices rupture?

A

secondary to delayed diagnosis

161
Q

children often have higher fever and more vomiting and diarrhea

A

appendicitis

162
Q

elderly: signs and symptoms can be minimal; may need right hemicolectomy if cancer suspected

A

appendicitis

163
Q

frequency of appendicitis in infants

A

appendicitis is infrequent in infants

164
Q

appendicitis: patient generally more ill; can have evidence of sepsis

A

peforaiton

165
Q

mcc of acute abdominal pain in the first trimester

A

appendicitis

166
Q

when is appendicitis likely to occur in pregnancy?

A

more likely to occur in the 2nd trimester but is not the most common cause of abdominal pain

167
Q

when in appendicitis more likely to perforate in pregnancy?

A

more likely to perforate in the third trimester - confused with contractions

168
Q

where do you make the appendectomy incision in pregnancy?

A

need to make incision where the patient is having pain - the appendix is displaced superiorly (cephalad)

169
Q

appendicitis: possible symptoms in 3rd trimester

A

ruq pain

170
Q

mortality rate of fetus in appendiceal rupture

A

35% fetal mortality with rupture

171
Q

management of pregnant women with suspected appendicitis

A

women with suspected appendicitis need beta-HCG drawn and abdominal ultrasound to rule out OB/GYN causes of abdominal pain

172
Q

appendix: can be benign or malignant mucous papillary tumor; needs resection (should open for these so you don’t spill tumor contents)

A

appendix mucocele

173
Q

tx: malignant appendix mucocele

A

need right hemicolectomy if malignant

174
Q

spread of tumor implants throughout the peritoneum

A

pseudomyxoma peritonei

175
Q

mcc of death in appendix mucocele

A

small bowel obstruction from peritoneal tumor srpead

176
Q

can mimic appendicitis; 10% go on to Crohn’s disease

A

regional ileitis

177
Q

nausea, vomiting, diarrhea

A

gastroenteritis

178
Q

ddx: presumed appendicitis in women

A

ruptured ovarian cyst, thrombosed ovarian vein, or regional enteritis not involving cecum
- tx: appendectomy (prevents future confounding diagnosis)

179
Q

causes of ileus

A

surgery (most common), electrolyte abnormalities (decreased K), peritonitis, ischemia, trauma, drugs

180
Q

dilatation is uniform throughout the stomach, small bowel, colon, and rectum without decompression

A

ileus

181
Q

there is bowel compression distal to the obstruction

A

obstruction

182
Q

children; get RLQ pain, diarrhea, fever, headaches, maculopapular rash, leukopenia; rare bleeding / perforation
- tx: bactrim

A

typhoid enteritis (salmonella)

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