chapter 35: small bowel.

Question 1

intestine: nutrient and water absorption

Answer 1

small intestine

Question 2

intestine: water absorption

Answer 2

large intestine

Question 3

portions of the duodenum

Answer 3

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

Question 4

portions of the duodenum that are retroperitoneal

Answer 4

descending and transverse portions

Question 5

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

Answer 5

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

Question 6

vascular supply duodenum

Answer 6

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

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

Question 7

100 cm long; long vasa recta, circular muscle folds

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

Answer 7

Jejunum

Question 8

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

Answer 8

jejunum

Question 9

150 cm long, short vasa recta, flat

- vascular supply: sma

Answer 9

ileum

Question 10

what is absorbed at the intestinal brush border?

Answer 10

maltase, sucrase, limit dextrinase, lactase

Question 11

normal sizes: small bowel / transverse colon / cecum

Answer 11

3 / 6 / 9 cm

Question 12

SMA eventually branches into the…

Answer 12

ileocolic artery

Question 13

cell types of the small intestine

Answer 13

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

Question 14

What do goblet cells secrete?

Answer 14

mucin secretion

Question 15

What do paneth cells secrete?

Answer 15

secretory granules, enzymes

Question 16

What do enterochromaffin cells secrete?

Answer 16

APUD, 5-hydroxytryptamine release, carcinoid precursor

Question 17

What do brunner’s cells secrete?

Answer 17

alkaline solution

Question 18

What do M cells secrete?

Answer 18

antigen-presenting cells in intestinal wall

Question 19

released into the gut; also in mother’s milk

Answer 19

IgA

Question 20

small bowel has both heme and Fe transporters

Answer 20

Fe

Question 21

where is iron absorbed?

Answer 21

duodenum

Question 22

where is folate absorbed?

Answer 22

terminal ileum

Question 23

where is b12 absorbed?

Answer 23

terminal ileum

Question 24

where are bile acids absorbed?

Answer 24

• ileum: non conjugated

- terminal ileum: conjugated

Question 25

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

Answer 25

phase 1: rest 2: acceleration and gallbladder contraction 3: peristalsis 4: deceleration

Question 26

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

Answer 26

motilin

Question 27

percent of bile salts reabsorbed

Answer 27

95%

Question 28

how are bile salts reabsorbed?

Answer 28

- 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

Question 29

When do gallstones form?

Answer 29

gallstones form after terminal ileum resection from malabsorption of bile salts

Question 30

how is diagnosis of short-gut syndrome made?

Answer 30

symptoms; not length of bowel

Question 31

diarrhea, steatorrhea, weight loss, nutritional deficiency | - lose fat, B12, electrolytes, water

Answer 31

short-gut syndrome

Question 32

stains: checks for fecal fat

Answer 32

sudan red stain

Question 33

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

Answer 33

schilling test

Question 34

how much bowel do you need to survive off TPN?

Answer 34

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

Question 35

Tx: short gut syndrome

Answer 35

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

Question 36

causes of steatorrhea

Answer 36

- gastric hyper secretion of acid | - interruption of bile salt resorption

Question 37

how does gastric hyper secretion of acid cause steatorrhea?

Answer 37

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

Question 38

how does interruption of bile salt resorption cause steatorrhea?

Answer 38

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

Question 39

Tx: steatorrhea

Answer 39

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

Question 40

causes of non healing fistulas

Answer 40

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

Question 41

characteristics of high-output fistulas

Answer 41

- more likely with proximal bowel (duodenum or proximal jejunum) - less likely to close with conservative management

Question 42

colonic fistulas vs small bowel | - which are more likely to close?

Answer 42

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

Question 43

nonhealing fistula: patients with persistent fever

Answer 43

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

Question 44

treatment: fistulas

Answer 44

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

Question 45

how do most non healing fistulas close?

Answer 45

majority close spontaneously without surgery

Question 46

surgical options of non healing fistulas

Answer 46

resect bowel segment containing fistula and perform primary anastomosis

Question 47

MCC obstruction without previous surgery

Answer 47

Small bowel: hernia | Large bowel: cancer

Question 48

MCC obstruction with previous surgery

Answer 48

Small bowel: adhesions | Large bowel: cancer

Question 49

- 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

Answer 49

proximal small bowel obstruction (open loop)

Question 50

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

Answer 50

Distal small bowel obstruction (open loop)

Question 51

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

Answer 51

small bowel obstruction (closed loop)

Question 52

- pain: continuous - vomiting: intermittent, not prominent; feculent when present - tenderness: diffuse - distention: marked - obstipation: present

Answer 52

colon and rectum obstruction

Question 53

type of bowel obstruction with no distention

Answer 53

proximal small bowel (open loop)

Question 54

AXR: obstruction

Answer 54

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

Question 55

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

Answer 55

need aggressive fluid resuscitaiton

Question 56

why is there air with bowel obstruction?

Answer 56

from swallowed nitrogen

Question 57

tx: bowel obstruction

Answer 57

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

Question 58

obstruction: surgical indications

Answer 58

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

Question 59

small bowel obstruction from gallstone usually in the terminal ileum

Answer 59

gallstone ileus

Question 60

imaging: what do you see in gallstone ileus?

Answer 60

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

Question 61

what causes gallstone ileus?

Answer 61

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

Question 62

tx: gallstone ileus

Answer 62

remove stone from terminal ileum - can leave gallbladder and fistula if patient too sick - if not too sick, perform cholecystectomy and close duodenum

Question 63

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

Answer 63

meckel's diverticulum

Question 64

what causes meckel's diverticulum?

Answer 64

caused by failure of closure of the omphalomesenteric duct

Question 65

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

Answer 65

pancreas tissue

Question 66

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

Answer 66

gastric mucosa

Question 67

two types of tissue in meckel's diverticulum

Answer 67

pancreatic and gastric tissue

Question 68

adults: MC presentation of meckel's diverticulum

Answer 68

obstruction

Question 69

when do you remove meckel's diverticulum?

Answer 69

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

Question 70

dx: meckel's diverticulum

Answer 70

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

Question 71

Tx: meckel's diverticulum

Answer 71

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

Question 72

what do you need to rule out in duodenal diverticula?

Answer 72

gallbladder-duodenal fistula

Question 73

primary management: duodenal diverticula

Answer 73

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

Question 74

Frequency of duodenal diverticula

Answer 74

Duodenal > jejunal > ileal

Question 75

Tx: duodenal diverticula

Answer 75

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)

Question 76

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

Answer 76

Crohn's Disease

Question 77

portion of alimentary where crohn's occurs

Answer 77

can occur anywhere from mouth to anus; usually spares rectum

Question 78

extraintestinal manifestations of crohn's

Answer 78

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

Question 79

crohn's: most commonly involved bowel segment

Answer 79

terminal ileum

Question 80

crohn's: 1st presentation in 5%

Answer 80

anal / perianal disease - Tx: flagyl - anal disease most common symptom: large skin tags

Question 81

crohn's disease: most common sites for initial presentation

Answer 81

- terminal ileum and cecum: 40% - colon only: 35% - small bowel only: 20% - perianal: 5%

Question 82

Dx: crohn's disease

Answer 82

colonoscopy with biopsies and enteroclysis can help make the diagnosis

Question 83

pathology: crohn's disease

Answer 83

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

Question 84

medical treatment: crohn's

Answer 84

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

Question 85

crohn's: agents affecting natural course of disease

Answer 85

no agents affect natural course of disease

Question 86

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

Answer 86

TPN

Question 87

percent of patient needing operation in crohn's

Answer 87

90%

Question 88

surgical indications: crohn's disease

Answer 88

``` obstruction abscess megacolon hemorrhage blind loop obstruction fissures fistulas: enterocutnaeous, perineal, anarectovaginal ```

Question 89

margins in crohn's surgery

Answer 89

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

Question 90

obstruction: crohn's

Answer 90

often partial and can be initially treated conservatively

Question 91

abscess: crohn's

Answer 91

usually treated with percutaneous drainage

Question 92

megacolon: crohn's

Answer 92

perforations occurs in 15%; usually contained

Question 93

hemorrhage: crohn's

Answer 93

unusual in crohn's but can occur

Question 94

blind loop obstruction: crohn's

Answer 94

need resection

Question 95

fissures: crohn's

Answer 95

no lateral internal sphincteroplasty in patients with crohn's disease

Question 96

enterocutaneous fistula: crohn's

Answer 96

can usually be treated conservatively

Question 97

perineal fistula: crohn's

Answer 97

unroof and rule out abscess; let heal on its own

Question 98

anorectovaginal fistula: crohn's

Answer 98

may need rectal advancement flap; possible colostomy

Question 99

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

Answer 99

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

Question 100

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

Answer 100

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

Question 101

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

Answer 101

stricturoplasty (longitudinal incision through stricture, close transversely)

Question 102

complications of stricturoplasty

Answer 102

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

Question 103

recurrence rate requiring surgery for Crohn's disease after resection

Answer 103

50% recurrence rate

Question 104

chron's: complications from removal of terminal ileum

Answer 104

- 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

Question 105

chron's: mechanisms of megaloblastic anemia

Answer 105

decreased b12 uptake

Question 106

crohn's: mechanism of osmotic diarrhea and steatorrhea

Answer 106

decreased bile salt uptake

Question 107

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

Answer 107

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

Question 108

crohns: mechanism of gallstones

Answer 108

can form after terminal ileum resection from malabsorption of bile salts

Question 109

what produces serotonin in carcinoid?

Answer 109

kulchitsky cells (enterochromaffin cell or argentaffin cell)

Question 110

what is serotonin (carcinoid) a part of?

Answer 110

part of amine precursor uptake decarboxylase system (APUD)

Question 111

breakdown product of serotonin - can measure this in urine

Answer 111

5-hiaa

Question 112

what does carcinoid tumor release?

Answer 112

serotonin | bradykinin

Question 113

carcinoid: caused by bulky liver metastases

Answer 113

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

Question 114

hallmark symptoms of carcinoid syndrome

Answer 114

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

Question 115

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

Answer 115

it indicates metastasis to liver (liver usually clears serotonin)

Question 116

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

Answer 116

perform cholecystectomy in case of future embolization

Question 117

carcinoid: best for localizing tumor not seen on ct scan

Answer 117

octreotide

Question 118

highest sensitivity for detecting a carcinoid tumor

Answer 118

chromogranin a level

Question 119

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

Answer 119

appendix carcinoid (ileum and rectum next most common)

Question 120

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

Answer 120

small bowel carcinoid

Question 121

tx: carcinoid in appendix | - 2cm or involving base

Answer 121

- 2 cm or involving base: right hemicolectomy

Question 122

tx: carcinoid anywhere else in GI tract aside from appendix

Answer 122

treat like cancer (segmental resection with lymphadenectomy)

Question 123

chemotherapy for carcinoid

Answer 123

streptozocin and 5FU; usually just for unresectable disease

Question 124

useful for carcinoid syndrome palliation

Answer 124

octreotide

Question 125

carcinoid: tx for bronchospasm

Answer 125

aprotinin

Question 126

carcinoid: tx for flushing

Answer 126

alpha blockers (phenothiazine)

Question 127

what can cause false elevations in 5-hiaa?

Answer 127

fruits

Question 128

same colon CA risk as ulcerative colitis

Answer 128

crohn's pancolitis

Question 129

- 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

Answer 129

intussusception in adults

Question 130

- most found in duodenum; present with bleeding, obstruction | - need resection when identified (often done with endoscope)

Answer 130

Adenomas - benign small bowel tumors

Question 131

- 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

Answer 131

Peutz-Jeghers syndrome

Question 132

mc extraintestinal malignancy in peutz-jeghers syndrome

Answer 132

breast cancer

Question 133

most common malignant small bowel tumor

Answer 133

adenocarcinoma (rare)

Question 134

where are most small bowel adenocarcinomas found?

Answer 134

high proportion are in the duodenum

Question 135

Symptoms of adenocarcinoma small bowel

Answer 135

obstruction, jaundice

Question 136

tx: small bowel adenocarcinoma

Answer 136

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

Question 137

duodenal CA risk factors

Answer 137

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

Question 138

- usually in jejunum and ileum; most extraluminal | - hard to differentiate compared with leiomyoma (>5 mitoses/HPF, atypia, necrosis)

Answer 138

leiomyosarcoma

Question 139

what do you need to rule out in leiomyosarcoma?

Answer 139

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

Question 140

tx: leiomyosarcoma in small bowel

Answer 140

resection; no adenectomy required

Question 141

- 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

Answer 141

Lymphoma - malignant small bowel tumor

Question 142

dx: lymphoma - malignant small bowel

Answer 142

abdominal ct, node sampling

Question 143

tx: lymphoma - small bowel

Answer 143

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

Question 144

survival rate small bowel lymphoma

Answer 144

40% 5 year survival rate

Question 145

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

Answer 145

parastomal hernias

Question 146

most common stomal infection

Answer 146

candida

Question 147

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

Answer 147

diversion colitis

Question 148

most common cause of stenosis of stoma | - tx: dilation if mild

Answer 148

ischemia

Question 149

most common cause of fistula near stoma site

Answer 149

crohn's disease

Question 150

underneath stoma stie, often caused by irrigation device

Answer 150

abscesses

Question 151

increased in patients with ileostomy

Answer 151

gallstones and uric acid kidney stones

Question 152

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

Answer 152

Appendicitis

Question 153

CT scan in appendicitis:

Answer 153

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

Question 154

where is the appendix most likely to perforate?

Answer 154

midpoint of anti-mesenteric border

Question 155

mcc appendicitis in children; can follow a viral illness

Answer 155

hyperplasia

Question 156

mcc appendicitis in adults

Answer 156

fecalith

Question 157

what is the sequence of events in appendiceal luminal obstruction?

Answer 157

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

Question 158

appendicitis: nonoperative situtation

Answer 158

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.

Question 159

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

Answer 159

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

Question 160

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

Answer 160

secondary to delayed diagnosis

Question 161

children often have higher fever and more vomiting and diarrhea

Answer 161

appendicitis

Question 162

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

Answer 162

appendicitis

Question 163

frequency of appendicitis in infants

Answer 163

appendicitis is infrequent in infants

Question 164

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

Answer 164

peforaiton

Question 165

mcc of acute abdominal pain in the first trimester

Answer 165

appendicitis

Question 166

when is appendicitis likely to occur in pregnancy?

Answer 166

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

Question 167

when in appendicitis more likely to perforate in pregnancy?

Answer 167

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

Question 168

where do you make the appendectomy incision in pregnancy?

Answer 168

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

Question 169

appendicitis: possible symptoms in 3rd trimester

Answer 169

ruq pain

Question 170

mortality rate of fetus in appendiceal rupture

Answer 170

35% fetal mortality with rupture

Question 171

management of pregnant women with suspected appendicitis

Answer 171

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

Question 172

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

Answer 172

appendix mucocele

Question 173

tx: malignant appendix mucocele

Answer 173

need right hemicolectomy if malignant

Question 174

spread of tumor implants throughout the peritoneum

Answer 174

pseudomyxoma peritonei

Question 175

mcc of death in appendix mucocele

Answer 175

small bowel obstruction from peritoneal tumor srpead

Question 176

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

Answer 176

regional ileitis

Question 177

nausea, vomiting, diarrhea

Answer 177

gastroenteritis

Question 178

ddx: presumed appendicitis in women

Answer 178

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

Question 179

causes of ileus

Answer 179

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

Question 180

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

Answer 180

ileus

Question 181

there is bowel compression distal to the obstruction

Answer 181

obstruction

Question 182

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

Answer 182

typhoid enteritis (salmonella)