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mechanical-bowel-obstruction-and-ileus-pathogenesis-and-clinical-findings

Mechanical Bowel Obstruction and Ileus: Pathogenesis and clinical findings Anti-motility Diabetic Sepsis drugs gastroparesis Nerves coordinating bowel peristalsis are disrupted Ileus: functional bowel ‘blockage’, no peristalsis Post- operation Hernia (no past surgery) Post-abdominal surgery Authors: Yan Yu, Wayne Rosen* Reviewers: Nicole Burma, Jason Baserman, Jennifer Au, Maitreyi Raman* * MD at time of publication Adhesions Note: • Complete obstruction typically presents with acute abdominal pain and related symptoms • Incomplete obstructions can present with either acute or Congenital abnormality GI neoplasms If partial obstruction: ↓ frequency of bowel movements Since gas/air sounds hollow to percussion Abdomen tympanic to percussion Mechanical obstruction: physical blockage of bowel lumen Inflammatory bowel disease (IBD) Gas (from swallowed air, bacterial fermentation, & CO2 made via HCO3- neutralization) & ingested gastro- intestinal (GI) contents accumulate before obstruction Accumulated GI contents contain salts and other osmotically active solutes that osmotically draw water into the GI tract Continued ↑ bowel distention & ↑ luminal pressure over time ↑ pressure squeezes shut intestinal blood vesselsà↓ bowel perfusion chronic abdominal pain If complete obstruction: Obstipation (no flatus) & absent bowel movements Irritation of autonomic nerves in visceral peritoneum Lower effective arterial blood volumeàdehydration Continued peristalsis proximal to obstruction continues to push GI contents against the obstruction If obstruction is proximal (closer to mouth), higher luminal pressure may force regurgitation of GI contents Bloating, cramping, anorexia Diffuse visceral abdominal pain Flat/low jugular venous pressure (JVP), resting tachycardia, orthostatic hypotension Severe abdominal pain (may come in waves), peritonitis, guarding, rigidity Hyperactive bowel sounds (proximal to obstruction) or absent bowel sounds (ileus) Nausea/vomiting Bowel ischemia and infarction, tissue necrosis, possible perforation +/- bacterial invasion (see relevant slides) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Re-Published December 15, 2021 on thecalgaryguide.com