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Small Bowel Obstruction

Small Bowel Obstruction. Phillip R. Mason USC School of Medicine August 30, 2007. The Questions that will be answered: What is it? Who does it happen to? Why does it happen? Where does it happen? How does it present? How is it diagnosed by radiology?. What?

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Small Bowel Obstruction

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  1. Small Bowel Obstruction Phillip R. Mason USC School of Medicine August 30, 2007

  2. The Questions that will be answered: • What is it? • Who does it happen to? • Why does it happen? • Where does it happen? • How does it present? • How is it diagnosed by radiology?

  3. What? - Blockage of material and air from passage to distal bowel. Who? - Everyone - About 75% of people with SBO have had previous abdominal surgery. Why?

  4. Where? May occur at any point in length of small bowel

  5. How does it present? Symptoms: Colicky abdominal pain, nausea, vomiting, and obstipation. Continued passage of gas and/or stool beyond 12 hours after onset of symptoms is characteristic of partial rather than complete obstruction. Signs: Abdominal Distention (Greater the farther distal the obstruction) and hyperactive, high pitched bowel sounds. Laboratory Findings: Intravascular volume depletion (consist of hemoconcentration and electrolyte abnormalities) Mild leukocytosis. Features of Strangulated Obstruction (Bowel Infarction): Acute Abdomen,Tachycardia, localized abdominal tenderness, fever, marked leukocytosis, and acidosis. Serum levels of amylase, lipase, lactate dehydrogenase, phosphate, and potassium may be elevated.

  6. How is it diagnosed? • Evaluation Goals: • Distinguishing mechanical obstruction from ileus • Determining the etiology of the obstruction • Discriminating partial from complete obstruction • Discriminating simple from strangulating obstruction. • History: • Prior abdominal operations • Presence of abdominal disorders (cancer or IBD) • Last BM and Flatus • Pediatrics - Ingestion of foreign body • Physical Exam: • Meticulous Search for Hernias (inguinal and femoral) • Rectal Exam to look for gross or occult blood. • The diagnosis is usually confirmed by Radiology

  7. Small Bowel Gas Pattern • Centrally located • Soft tissue across entire lumen • Colon Gas Pattern • Peripheral Located • Mostly not overlapping • Haustra markings

  8. Abdominal series Radiograph of the abdomen in a supine position Radiograph of the abdomen in an upright position Radiograph of the chest in an upright position. Most Specific Finding: The Triad Dilated small-bowel loops (>3 cm in diameter) Air-Fluid levels on upright films Paucity of air in the colon. Sensitivity is 70 to 80%. Specificity is low, because ileus and colonic obstruction have similar appearing findings. Despite some limitations, Plain films remain an important study because of their widespread availability and low cost.

  9. Flat Abdominal Film Dilated Loops of Small Bowel No Air in Colon or Rectum

  10. Upright Abdominal Film Air - Fluid Levels Dilated Small Bowel

  11. Computed Tomographic (CT) scanning • Study preformed with oral and IV contrast. • Findings: • Discrete transition zone with dilation of bowel proximally and decompressed distally • Intraluminal contrast that does not pass beyond the transition zone • Colon containing little gas or fluid. • Strangulation: • Suggested by thickening of the bowel wall, pneumatosis intestinalis (air in the bowel wall), portal venous gas, mesenteric haziness, and poor uptake of intravenous contrast into the wall of the affected bowel. • Offers a global evaluation of the abdomen. • Important when intestinal obstruction represents only one possible diagnosis in all acute abdominal conditions. • Sensitivity 80 to 90% (More sensitive the higher grade obstruction) • Specificity 70 to 90%

  12. Dilated Loops of Small Bowel with Air-Fluid levels • Area of non-dilated small bowel. • Absence of Air in the Colon.

  13. Pneumatosis Intestinalis • Dilated Loops of SB • Air in Wall of SB • No Air in Colon

  14. SBO or Illeus?

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