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Flashcards in Fiser Chapter 35 SMALL BOWEL Deck (68)
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1

Duodenum blood supply

Superior and inferior pancreaticoduodenal arteries
Superior off gastroduodenal
Inferior off SMA

2

Maximum site of all absorption

-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?

3

Jejunum blood supply

SMA

4

Ileum blood supply

SMA

5

Intestinal brush border enzymes

Maltase

Sucrase

Limit dextrinase

Lactase

6

Normal diameters for small bowel, colon, and cecum

3 / 6 / 9 cm

7

Gut cell types

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

8

Ab released into gut

IgA (also in breast milk)

9

Heme and iron transport

small bowel

10

Migrating motor complex phases

Gut motility:

Phase I - rest

Phase II - acceleration and GB contraction

Phase III - peristalsis (motilin)

Phase IV - deceleration

11

Most important hormone for migrating motor complex

motilin

12

Bile salt reabsorption

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)

13

Why do gallstones form after terminal ileum resection?

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

14

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

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)

15

Steatorrhea causes

-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

16

Causes of nonhealing fistula

FRIENDS

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

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

17

Patient with nonhealing fistula presents with fever

Check for abscess: fistulogram, CT, UGI with SBFT

18

Fistula treatment

-NPO, TPN, stoma appliance, octreotide

Most close without surgery

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

19

Most common causes of obstruction

Small bowel: hernia, if prior surgery adhesions
Large bowel: cancer

20

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

Bowel obstruction

21

SBO tx

Aggressive fluid resuscitation, bowel rest, NG tube
Cures 80% of partial SBO, 40% of complete SBO

22

Surgical indications for SBO

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

23

Patient with SBO and air in the biliary tree

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

24

1yo child with painless lower GI bleed

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

25

Most common tissue found in Meckel's

Pancreas, can cause diverticulitis

26

Most likely type of meckel's to be symptomatic

Gastric mucosa (bleeding)

27

Meckel's presentation

Either bleeding <2yo, or obstruction in adults

28

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

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

29

Meckel's dx and tx

-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

Small bowel diverticula

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