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Flashcards in SMALL B Deck (30):
1

Small bowel obstruction: surgical treatment goals

(a) distinguish mechanical obstruction from ileus (b) determine the etiology of the obstruction (c) discriminate partial from complete obstruction, and (d) discriminate simple from strangulating obstruction

2

Intraluminal

Foreign bodies, gallstones, meconium

3

Intramural

Tumors, Crohn's disease-- associated inflammatory strictures

4

Extrinsic

Adhesions, hernias, carcinomatosis Most common etiology is adhesions

5

Intestinal obstruction sx

Crampy intermittent abdominal pain and distension No BM or flatus Previous surgery Hypoactive/hyperactive bowel sounds Metallic quality Ascites-- intravascular volume depleted Severe, persistent pain suggests strangulation or perforation

6

Lab results

BUN/CR elevated-- >20:1 Hypernatremia Urine electrolytes Hemoconcentration Acidosis Leukocytosis

7

Imaging

*Supine and erect abdominal x-ray Erect CXR* --> Free air Single-contrast barium enema Small bowel series CT

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What is the best imaging for SBO and what are the findings?

Abdominal x-ray series -Dilated small bowel loops (> 3 cm) -Air-fluid levels seen on upright films -A paucity of air in colon

9

CT findings

*PO contrast*, water soluble -Transition zone: dilation proximally, decompression distally (contrast proximally, no contrast distally) -Colon has little gas or fluid -CT shows strangulation

10

CT findings suggestive of strangulation

thickening of the bowel wall pneumatosis intestinalis (air in the bowel wall) portal venous gas mesenteric haziness poor uptake of intravenous contrast into the wall of the affected bowel -IV contrast if compromise of vasculature is suspected

11

Small Bowel Series

Detects low-grade or partial small bowel obstruction Water soluble PO contrast (or in NG tube if vomiting) Sequential x-rays to follow where contrast is traveling

12

Approach to SBO

Management based on: location of obstruction, proximal, mid-gut, distal Level or severity: partial, complete, strangulated, closed-loop

13

Strangulated bowel obstruction

If the intramural pressure becomes high enough, intestinal microvascular perfusion is impaired, leading to intestinal ischemia and, ultimately, necrosis.

14

Partial SBO

only a portion of the intestinal lumen is occluded, allowing passage of some gas and fluid. Continued passage of flatus and/or stool beyond 6 to 12 hours after onset of symptoms is characteristic.

15

Complete SBO

lumen becomes obstructed, gas and fluid accumulate proximally, the bowel distends and intraluminal and intramural pressures rise, and the development of strangulation is more likely.

16

Closed loop obstruction

a segment of intestine is obstructed both proximally and distally (e.g., with volvulus). The accumulating gas and fluid cannot escape either proximally or distally from the obstructed segment, leading to a rapid rise in luminal pressure and a rapid progression to strangulation.

17

Findings of proximal SBO

Vomiting: +++ Character of vomit: bilious Flatus/stool: None past 6-12 hours of onset Abdominal distension: absent Bowel sounds: hyperactive initially, minimal in late stages

18

Findings of distal SBO

Vomiting: + Character of vomit: feculent Flatus/stool: None past 6-12 hours of onset Abdominal distension: +++ Bowel sounds: hyperactive initially, minimal in late stages

19

SBO Conservative tx: initially recommended for

Partial SBO (monitor for 40 hours; if not improving-- surgery.) Obstruction in early post-op period (monitor for 2-3 weeks) Intestinal obstruction due to Crohn's disease Carcinomatosis *Observe closely, undergo serial exams *Watch for: tachycardia, abdominal tenderness, or an increase in white cell count

20

SOB Conservative Tx

-Fluid resuscitation and monitoring (isotonic IVF, monitor urine output, consider invasive hemodynamic monitoring) -NG tube for decompression -Pre-op abx (broad spectrum, gram negatives, and anaerobes) -Serial imaging, exams

21

Surgery: Why?

Minimize risk for bowel strangulation-- goal is to operate before onset of irreversible ischemia Look at big clinical picture to determine who should go to OR

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Surgical options

Exploratory laparotomy Exploratory laparoscopy

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Findings that suggest viability

Normal color Peristalsis Marginal arterial pulsations

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Resections: Short lengths

Resect, primary anastomosis of remaining intestine

25

Resections: Large portion

Conservative measures -Get rid of obviously necrotic bowel -Leave bowel of uncertain viability, take a "second look" at 24 hours -Definitive resection if needed

26

Complications of bowel obstruction

Fluid and electrolyte imbalance Dehydration... hypovolemic shock Ischemia of bowel leading to strangulation, necrosis, perforation Peritonitis Sepsis Death

27

Ileus

Alteration in motility of GI tract resulting in a functional obstruction Temporary

28

Paralytic ileus

Minimal abdominal pain, usually continuous Decreased or absent bowel sounds Gas throughout small and large bowel on plain x-ray

29

Return of normal motility

Small-intestinal motility: 24 hours after laparotomy Gastric motility: in 48 hours Colonic motility: in 3-5 days

30

Management of ileus

Limiting oral intake Correcting the underlying inciting factor If vomiting or abdominal distention is prominent- place NG tube Fluid and electrolyte replacement IV fluid maintenance until ileus resolves If the duration of ileus is prolonged, TPN may be required