NMS. Surgery

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Part VI ♦ Special Subjects II. Previous surgical history

A. Obstruction with previous abdominal surgery is usually adhesive disease and usually improves with non-operative management (nasogastric [NG] decompression and supportive care). B. In the absence of previous surgery, the source of obstruction may be a malignancy, perforation, or volvulus and requires intervention. III. Physical Exam A. Abdominal exam: Significant for distention. B. Incarcerated hernias: Exam should reveal hernias (inguinal, femoral, umbilical, and ventral). Diagnostic Studies I. Laboratory analysis: Important as patients often present with dehydration and significant electrolyte and acid–base abnormalities. II. Abdominal x-ray: May reveal air in a nonanatomic location. A. Cecal and sigmoid volvulus: Characteristic distended colon loops visible on x-ray. B. Small bowel obstruction (SBO) 1. Shows normal air pattern in the stomach and colon, with distended, air-filled loops of small bowel. 2. Multiple air-fluid levels on x-ray indicate obstruction. Differential Diagnosis I. Mechanical obstruction: Physical blockage of the small or large intestine by internal or external mass, stricture, or intestinal twisting. A. Terminology 1. Acute obstruction: Occurs over hours. 2. Chronic obstruction: Develops over weeks to months and characterized by malnutrition and chronic illness. 3. Strangulating obstruction a. Occurs when the blood supply to a segment of bowel is compromised, leading to gangrene and perforation. b. Signs include fever, tachycardia, peritoneal signs, acidosis, and leukocytosis. c. Constitutes a surgical emergency. 4. Incarceration: A hernia that cannot be reduced; may also be strangulated. 5. Closed loop obstruction: Both limbs of a segment of bowel are obstructed. a. Distention: Proximal bowel distends, and symptoms of obstruction develop. b. Closed loop: More prone to perforation because it cannot decompress.