Fiser Chapter 35 SMALL BOWEL Flashcards

1
Q

Duodenum blood supply

A

Superior and inferior pancreaticoduodenal arteries
Superior off gastroduodenal
Inferior off SMA

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2
Q

Maximum site of all absorption

A

-Jejunum: most nutrients, and 95% of NaCl, and 90% of H2O

  • Duodenum: iron
  • Ileum: non-conjugated bile acids
  • Terminal ileum: B12, conjugated bile acids, folate?
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3
Q

Jejunum blood supply

A

SMA

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4
Q

Ileum blood supply

A

SMA

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5
Q

Intestinal brush border enzymes

A

Maltase

Sucrase

Limit dextrinase

Lactase

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6
Q

Normal diameters for small bowel, colon, and cecum

A

3 / 6 / 9 cm

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7
Q

Gut cell types

A

Absorptive cells

Goblet cells (mucin secretion)

Paneth cells (secretory granules, enzymes)

Enterochromaffin cells (APUD, 5-hydroxytryptamine release, carcinoid precursor)

Brunner’s glands (alkaline solution)

Peyer’s patches (lymphoid tissue; increased in ileum)

M cells: Antigen presenting cells

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8
Q

Ab released into gut

A

IgA (also in breast milk)

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9
Q

Heme and iron transport

A

small bowel

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10
Q

Migrating motor complex phases

A

Gut motility:

Phase I - rest

Phase II - acceleration and GB contraction

Phase III - peristalsis (motilin)

Phase IV - deceleration

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11
Q

Most important hormone for migrating motor complex

A

motilin

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12
Q

Bile salt reabsorption

A

95% is reabsorbed

50% passive absorption (non-conjugated) in ileum and a little bit colon

50% active resorption (conjugated) in terminal ileum ONLY (Na/K ATPase)

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13
Q

Why do gallstones form after terminal ileum resection?

A

It’s the only place where conjugated bile salts are reabsorbed

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14
Q

Diarrhea, steatorrhea, weight loss, nutritional deficiency after bowel resection

A

Short gut syndrome: generally need at least 75cm to survive off TPN; 50 cm with competent ICV

Dx: -Sudan red stain: fecal fat
-Schilling test: checks for B12 abruption (radiolabeled B12 in urine)

Tx: Restrict fat, PPI to reduce acid, Lomotil (diphenoxylate and atropine)

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15
Q

Steatorrhea causes

A
  • Gastric hypersecretion of acid (decreased intestinal motility in acidic env’t)
  • Interruption of bile salt resorption (TI resection, interferes with micelle formation and fat absorption)

Tx: Lomotil (diphenoxylate and atropine), decrease oral intake especially fats, pancrease, PPI

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16
Q

Causes of nonhealing fistula

A

FRIENDS

  • Foreign body
  • Radiation
  • Infection or IBD
  • Epithelialization
  • Neoplasm
  • Distal obstruction
  • Sepsis/steroids

Other: high output, small bowel less likely to close than colonic

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17
Q

Patient with nonhealing fistula presents with fever

A

Check for abscess: fistulogram, CT, UGI with SBFT

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18
Q

Fistula treatment

A

-NPO, TPN, stoma appliance, octreotide

Most close without surgery

Surgery: resect small bowel segment containing fistula and perform primary anastomosis

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19
Q

Most common causes of obstruction

A

Small bowel: hernia, if prior surgery adhesions

Large bowel: cancer

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20
Q

Patient with nausea, emesis, crampy abdominal pain, failure to pass gass or stool, AXR shows air-fluid level, distended loops of small bowel, distal decompression

A

Bowel obstruction

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21
Q

SBO tx

A

Aggressive fluid resuscitation, bowel rest, NG tube

Cures 80% of partial SBO, 40% of complete SBO

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22
Q

Surgical indications for SBO

A

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

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23
Q

Patient with SBO and air in the biliary tree

A

Gallstone ileus, gallstone usually in TI

Caused by fistula between gallbladder and second portion of duodenum

Tx:

  • Remove stone from TI (if any signs of ischemia at cecum then resect)
  • If NOT too sick, also perform cholecystectomy and close duodenum
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24
Q

1yo child with painless lower GI bleed

A

Meckel’s (true) diverticulum, caused by failure of closure of omphalomesenteric duct

Rule of 2’s: 2 ft from ICV, 2% of population, presents with bleeding in first 2 years of life

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25
Q

Most common tissue found in Meckel’s

A

Pancreas, can cause diverticulitis

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26
Q

Most likely type of meckel’s to be symptomatic

A

Gastric mucosa (bleeding)

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27
Q

Meckel’s presentation

A

Either bleeding <2yo, or obstruction in adults

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28
Q

What do you do if you encounter an incidental Meckel’s?

A

Usually not removed unless gastric mucosa suspected (diverticulum feels thick) or has a very narrow neck

29
Q

Meckel’s dx and tx

A

-Meckel’s 99Tc scan if trouble localizing (mucosa lights up)

  • Diverticulectomy for uncomplicated diverticulitis or bleeding
    • Indications for resection: complicated diverticulitis (perforation), neck > 1/3 diameter of normal bowel lumen, or diverticulitis involves the base
30
Q

Small bowel diverticula

A

Duodenal > jejunal > ileal

Need to rule out gallbladder-duodenal fistula

Observe unless perforated, bleeding, obstructed, or symptomatic:

  • Surgery: segmental resection (avoid Whipple!)
  • Biliary symptoms: juxta-ampullary needs choledochojejunostomy
  • Pancreatitis: ERCP with stent
31
Q

25yo Jew with intermittent abdominal pain, diarrhea, weight loss, fistulas, anal skin tags

A

Crohn’s, anywhere from mouth to anus, though usually spares rectum

Most commonly involved segment is TI

32
Q

Crohn’s extraintestinal manifestations

A
  • Arthritis, arthralgias
  • Pyoderma gangrenosum
  • Erythema nodosum
  • Ocular disease
  • Growth failure
  • Megaloblastic anemia from folate and B12 malabsorption
33
Q

Crohn’s dx

A

Colonoscopy with biopsies and enteroclysis can help

Path: transmural involvement, segmental disease (skin lesions), cobblestoning, narrow deep ulcers, creeping fat, fistulas

Crohn’s pancolitis: same colon CA risk as UC

34
Q

Crohn’s tx

A
  • 5-ASA, loperamide
  • Acute flares: steroids
  • Steroid-resistance or fistulas: Infliximab (TNF-alpha inhibitor)
  • TPN may induce remission and fistula closure with small bowel disease

NO agents affect natural course of disease

90% eventually need an operation

35
Q

Crohn’s surgical indications

A

Just need 3cm away from gross disease, do not need clear path margins.
Unlike in UC, surgery NOT curative

  • Obstruction (if fails nonop mgt)
  • Abscess (drainage)
  • Megacolon
  • Hemorrhage (unusual)
  • Blind loop obstruction
  • Fissures (NO lateral internal sphincteroplasty in Crohn’s)
  • EC fistula (usually nonop)
  • Perineal fistula (unroof to check for abscess, then let heal)
  • Anorectovaginal fistulas (may need rectal advancement flap or colostomy)
36
Q

Crohn’s with diffuse colon disease, what is tx

A

Proctocolectomy and ileostomy (no pouches or ileoanal anastomosis)

37
Q

What do you do if you are attempting an appy and find IBD with normal appy?

A

Appendectomy if cecum not involved (avoids future confounding diagnosis)

38
Q

Patient with Crohn’s and multiple bowel strictures and past operations

A

Stricturoplasty: longitudinal incision through stricture, close transversely, consider if has multiple bowel strictures to save small bowel length, not good 1st operation as leaves disease behind

10% leakage/abscess/fistula rate

39
Q

Incidence of Crohn’s recurrence requiring more surgery after resection?

A

50%

40
Q

Terminal ileum removal, complications?

A
  • Megaloblastic anemia (decreased B12 uptake)
  • Osmotic diarrhea and steatorrhea (decreased bile salt uptake)
  • Gallstones from above too
  • Ca oxalate kidney stones (decreased oxalate binding to calcium d/t increased intraluminal fat) -> oxalate absorption in colon and released in urine -> hyperoxaluria and stones
41
Q

Intermittent flushing and diarrhea, asthma symptoms, CT negative but octreotide scan localizes liver mass

A

Carcinoid syndrome:

Kulchitsky cells (enterochromaffin or argentaffin cell) produce SEROTONIN, part of APUD (amine precursor uptake decarboxylase system) -> 5-HIAA is a breakdown product of serotonin measured in urine (also false elevation with eating fruits) -> bulky liver mets -> diarrhea (serotonin) and flushing (kallikrein)

Bradykinin also released -> asthma symptoms

Right heart valve lesions

Tx: liver mets resection, cholecystectomy in case of future embolization

42
Q

Most common sites for carcinoid

A
  1. Appendix
  2. Ileum
  3. Rectum

If small bowel: increased risk for multiple primaries and second unrelated malignancy

43
Q

Carcinoid tx

A
  • Appendectomy (< 2 cm)
  • Right hemicolectomy if 2 cm or greater or involving base
  • Segmental resection with lymphadenectomy if anywhere else in GI tract
  • Streptozocin and 5FU for unresectable disease
  • Octreotide for syndrome palliation
  • Aprotinin for bronchospasm
  • Alpha-blockers (phenothiazine) for flushing
44
Q

Intusussception tx

A

Adult: presents as obstruction, can be from tumor, often a malignant lead point (small bowel or cecal)

Tx: RESECTION

45
Q

Small bowel tumors

A

Adenomas (benign)

Peutz-Jeghers syndrome (benign)

Adenocarcinoma (malignant)

Leiomyosarcoma (malignant)

Lymphoma (malignant)

46
Q

Small bowel adenomas

A

Most often in duodenum

Present with bleeding or obstruction

Need resection (endoscopic) if identified

47
Q

Peutz-Jeghers syndrome

A

Autosomal dominant

Hamartomas throughout GI tract

Mucocutaneous melanotic skin pigmentation

Patients have increased extraintestinal malignancies (breast cancer most commonly) and small risk of GI malignancies; NO prophylactic colectomy

48
Q

Small bowel adenocarcinoma

A

Rare, though most common malignant SB tumor
Most in duodenum

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

49
Q

Duodenal adenoCa risk factors

A
  • FAP
  • Gardner’s
  • Polyps
  • Adenomas
  • Von Recklinghausen’s (neurofibromatosis 1)
50
Q

Leiomyosarcoma

A

Usually in jejunum and ileum, most extraluminal

Hard to differentiate from leiomyoma (> 5 mitoses/HPF, atypia, necrosis)

Make sure not a GIST: check C-kit

Tx: Resection, NO adenectomy required

51
Q

Lymphoma

A

Usually in ileum, and NHL B cell type, 40% 5-year survival

Associated with:

  • Wegener’s
  • SLE
  • AIDS
  • Crohn’s
  • Celiac sprue

In post-transplant patient: increased risk of bleeding and perforation

Dx: CT, node sampling

Tx: Wide en bloc resection (include nodes) unless 1st or 2nd portion of the duodenum (chemorad, NO Whipple)

52
Q

Parastomal hernias

A

Highest incidence with colostomies, generally well tolerated and do not need repair unless symptomatic

53
Q

Most common stomal infection

A

Candida

54
Q

Diversion colitis (Hartmann’s pouch) is due to what

A

Lack of short-chain fatty acids

Tx: short chain fatty acid enemas

55
Q

Stomal complications

A

Parastomal hernias (colostomies)

Infection (candida)

Diversion colitis (lack of short chain fatty acids)

Stenosis (d/t ischemia - dilate)

Fistula (Crohn’s)

Abscess (irrigation device causes it)

Gallstones and uric acid kidney stones (ileostomies)

56
Q

25yo with anorexia followed by periumbilically abdominal pain, then vomiting, then RLQ pain. Normal WBC.

A

Appendicitis: luminal obstruction -> appy distension -> venous congestion and thrombosis -> ischemia -> gangrene necrosis -> rupture

57
Q

CT findings in appendicitis

A
  • diameter > 7 mm
  • wall thickness > 2 mm
  • fat stranding
  • no contrast in in appendiceal lumen, try to give rectal contrast
58
Q

Appendiceal area most likely to perforate

A

Midpoint of anti-mesenteric border

59
Q

MCC of appendicitis in children and adults

A

Infants: rare

Children: hyperplasia, can follow a viral illness

Adults: fecalith

60
Q

Appy tx

A

Walled-off perforation (elderly): perc drainage, interval appy when symptoms improving; consider follow-up barium enema or colonoscopy to rule out perforated cecal colon CA

61
Q

Difference in presentation between kids, adults, elderly in appy

A
  • Children and eldery higher rupture rate d/t delayed diagnosis
  • Children higher fever, more vomiting and diarrhea
  • Elderly signs/symptoms can be minimal, may need R hemicolectomy if cancer suspected
62
Q

Most common cause of acute abdominal pain in 1st trimester of pregnancy

A
  • Appendicitis. Make incision where pain is. Displaced superiorly.
  • Although more likely to occur in 2nd trimester, and more likely to perforate in 3rd trimester (RUQ pain)
  • 35% fetal mortality with rupture
63
Q

Appendix mucocele

A
  • Can be benign or malignant mucous papillary tumor
  • Needs OPEN resection (don’t spill tumor contents), and Right hemicolectomy if malignant
  • Rupture can cause pseudomyxoma peritonei
  • MCC death is small bowel obstruction from peritoneal tumor spread
64
Q

Regional ileitis

A

Can mimic appendicitis, and 10% go on to Crohn’s

65
Q

What do you do if you attempt appendectomy but find ruptured ovarian cyst, thrombosed ovarian vein, or regional enteritis not involving cecum?

A

Still perform appy (prevents future confounding diagnosis)

66
Q

Most common cause of ileus

A

Surgery

Also hypokalemia, peritonitis, ischemia, trauma, drugs

67
Q

Ileus versus obstruction

A

Ileus: dilatation uniform through stomach, small bowel, colon, rectum, NO decompression

Obstruction: bowel decompression distal to obstruction

68
Q

Child with RLQ pain, diarrhea, fever, headaches, maculopapular rash, leukopenia, rarely bleeding or perforation

A

Typhioid enteritis: caused by salmonella

Tx: Bactrim