SHM's Clinical Quick Talks-Evaluation of Acute Small Bowel Obstruction (SBO)

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This document provides an evaluation of acute small bowel obstruction (SBO). It outlines the presenting symptoms of SBO, which include crampy abdominal pain, nausea/vomiting (more common with proximal obstructions), abdominal distention (more common with distal obstructions), and constipation (which can progress to obstipation with complete SBO). The document also highlights the importance of eliciting pertinent past medical history, such as previous abdominal surgeries, abdominal disorders, and risk factors for ischemic colitis. <br /><br />The physical exam findings and maneuvers that are clinically interpreted when evaluating SBO are discussed. These include tachycardia, hypotension, fever, and dry mucus membranes indicating possible complications of dehydration or sepsis. Other findings, such as high fever, rebound tenderness, guarding, and metabolic acidosis, may suggest possible infection, bowel necrosis, or bowel perforation. The document also mentions the importance of abdominal inspection, auscultation, percussion, palpation, and digital rectal examination to detect signs of obstruction. <br /><br />Various laboratory studies are recommended in the evaluation of SBO. These include a complete blood count (CBC) with differential to assess for leukocytosis and anemia, a basic metabolic panel (BMP) to assess for hypovolemia and metabolic abnormalities, arterial blood gas to evaluate for metabolic alkalosis or acidosis, serum lactate to assess for mesenteric ischemia, and blood cultures to diagnose bacteremia. <br /><br />The document further explains the imaging studies used to evaluate SBO, such as an obstruction series X-ray which shows dilated loops of bowel with air-fluid levels, and follow-up with abdominal and pelvic CT with oral and IV contrast which can determine the severity, site, cause, and presence of ischemia. It notes that MRI and ultrasound can be alternatives to CT in certain cases. <br /><br />Finally, some clinical pearls are provided, such as the classical presentation of SBO being less common in partial SBOs, adhesions not being directly visible on imaging modalities, and oral contrast being contraindicated in suspected complete SBO.

Asset Subtitle

Ami Patel, Kathryn Haroldson

Keywords

acute small bowel obstruction

SBO evaluation

presenting symptoms

abdominal pain

nausea/vomiting

abdominal distention

constipation

past medical history

physical exam findings

imaging studies