Snapshot An 80-year-old man with a history of divertulosis and multiple episodes of diverticulitis presents to the emergency room for increasing crampy abdominal pain, nausea, and vomiting. He last had a bowel movement 4 days ago and has had tiny amounts of diarrhea. He has not had any flatus since last night. On physical exam, his abdomen is noted to be distended, somewhat rigid, and tender to palpation. Bowel sounds are absent. A digital rectal exam reveals hard stool in the rectal vault. An abdominal radiograph shows dilated loops of bowel but no free air under the diagphragm. A computed tomography of his abdomen and pelvis confirms the presence of dilated loops of bowel and a large fecolith. Introduction Overview large bowel obstruction, or LBO, is a surgical emergency and requires intervention obstruction may be partial or complete complete obstructions require immediate surgical intervention Epidemiology demographics elderly patients etiology volvulus intussusception colonic mass/malignancy diverticular disease fecal impaction stricture incarcerated hernia risk factors chronic constipation Pathogenesis mechanism mechanical obstruction in the large bowel causes bowel dilatation above the point of obstruction causes bowel edema and ischemia electrolyte abnormalities Prognosis prognostic variable if treated early, mortality for LBO is low if there is bowel ischemia or perforation, mortality is higher Presentation History chronic constipation lack of flatus indicates complete obstruction some passage of flatus or stool indicates partial obstruction Symptoms crampy abdominal pain nausea and vomiting bloating Physical exam inspection abdominal distention motion tenderness to palpation abdominal rigidity quiet or absent bowel sounds provocative tests digital rectal exam may reveal hard stool in the rectal vault Imaging Abdominal radiographs indications all patients screen for free air under the diaphragm views flat upright findings dilated bowel Contrast radiography with enema indication if CT findings are equivocal and volvulus is suspected findings “bird’s beak” appearance Computed tomography (CT) of abdomen and pelvis with contrast indications imaging of choice for diagnosis of LBO distinguishes between a partial or complete obstruction findings mechanical obstruction identified dilated loops of bowel contrast agent gastrografin should be used if bowel perforation is suspected Studies Serum labs basic metabolic panel to correct any electrolyte abnormalities lactate to evaluate for bowel ischemia complete blood cell count white blood cells are only mildly elevated Differential Small bowel obstruction key distinguishing factor dilated loops of small bowel seen on imaging rather than dilated loops of large bowel Ogilvie syndrome key distinguishing factor no mechanical lesion on CT imaging that can cause the obstruction Treatment Lifestyle modified diet indications for patients with history of obstruction modalities high-fiber diet stool softeners Medical observation and bowel rest indications mild symptoms without vomiting modalities intravenous fluids correct electrolyte abnormalities nasogastric decompression and bowel rest indications abdominal distention vomiting Surgical exploratory laparotomy indications complete LBO bowel ischemia volvulus Complications Ischemic colitis Bowel perforation