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

31

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

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

Most commonly involved segment is TI

32

Crohn's extraintestinal manifestations

-Arthritis, arthralgias
-Pyoderma gangrenosum
-Erythema nodosum
-Ocular disease
-Growth failure
-Megaloblastic anemia from folate and B12 malabsorption

33

Crohn's dx

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

Crohn's tx

-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

Crohn's surgical indications

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

Crohn's with diffuse colon disease, what is tx

Proctocolectomy and ileostomy (no pouches or ileoanal anastomosis)

37

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

Appendectomy if cecum not involved (avoids future confounding diagnosis)

38

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

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

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

50%

40

Terminal ileum removal, complications?

-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

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

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

Most common sites for carcinoid

1. Appendix
2. Ileum
3. Rectum

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

43

Carcinoid tx

-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

Intusussception tx

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

Tx: RESECTION

45

Small bowel tumors

Adenomas (benign)

Peutz-Jeghers syndrome (benign)

Adenocarcinoma (malignant)

Leiomyosarcoma (malignant)

Lymphoma (malignant)

46

Small bowel adenomas

Most often in duodenum

Present with bleeding or obstruction

Need resection (endoscopic) if identified

47

Peutz-Jeghers syndrome

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

Small bowel adenocarcinoma

Rare, though most common malignant SB tumor
Most in duodenum

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

49

Duodenal adenoCa risk factors

-FAP
-Gardner's
-Polyps
-Adenomas
-Von Recklinghausen's (neurofibromatosis 1)

50

Leiomyosarcoma

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

Lymphoma

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

Parastomal hernias

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

53

Most common stomal infection

Candida

54

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

Lack of short-chain fatty acids

Tx: short chain fatty acid enemas

55

Stomal complications

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

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

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

57

CT findings in appendicitis

-diameter > 7 mm
-wall thickness > 2 mm
-fat stranding
-no contrast in in appendiceal lumen, try to give rectal contrast

58

Appendiceal area most likely to perforate

Midpoint of anti-mesenteric border

59

MCC of appendicitis in children and adults

Infants: rare

Children: hyperplasia, can follow a viral illness

Adults: fecalith

60

Appy tx

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

Difference in presentation between kids, adults, elderly in appy

-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

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

-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

Appendix mucocele

-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

Regional ileitis

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

65

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

Still perform appy (prevents future confounding diagnosis)

66

Most common cause of ileus

Surgery

Also hypokalemia, peritonitis, ischemia, trauma, drugs

67

Ileus versus obstruction

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

Obstruction: bowel decompression distal to obstruction

68

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

Typhioid enteritis: caused by salmonella

Tx: Bactrim