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Mr Lantern is a 70-year-old man with a history of hypertension, type 2 DM, and coronary artery disease who presents with intermittent, crampy, mid-abdominal pain that started 2 days ago and is associated with nausea, vomiting, constipation, and an unintentional weight loss of 10 lb over the past 2 months. No fever or chills, hematuria, dysuria, or chest pain is noted. The patient has no history of gallstones, kidney stones, or abdominal surgeries. Medications: lisinopril, aspirin, metoprolol, simvastatin, and insulin. He reports no alcohol use. On physical examination the patient looks moderately distressed. Vitals are significant for orthostasis with the heart rate increasing by 20 beats/min and blood pressure dropping by 20 mm Hg when the patient sits up. The patient is afebrile. Sclera are nonicteric. Cardiac and lung examinations are normal except for an irregularly irregular rhythm. Abdominal examination reveals a distended abdomen with hyperactive bowel sounds. Rectal examination is normal. Stool is Hemoccult positive.

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1. What should be included in your DDX?

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Answer

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  1. Large bowel obstruction (LBO)

    • Small bowel obstruction (SBO)

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Large Bowel Obstruction

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LBO typically presents with severe, diffuse, crampy abdominal pain that appears in waves associated with vomiting. Abdominal pain and the absence of bowel movements or flatus suggest bowel obstruction. Initially, patients may have several bowel movements as the bowel distal to the obstruction is emptied. Obstruction can be due to cancer, volvulus, diverticular disease, or external compression from metastatic cancer, etc. LBO may be complicated by bowel infarction, perforation, peritonitis, and sepsis. Plain x-rays of the abdomen may show air-fluid levels and distension of large bowel (>6 cm) and also free air under the diaphragm in the case of perforation. CT scan of the abdomen and pelvis is also accurate in the diagnosis of LBO (91% sensitive and 91% specific). Hypaque enema (water-soluble enema) is 96% sensitive and 98% specific and is highly accurate for larger bowel obstruction. It can be both diagnostic and therapeutic. It can also exclude acute colonic pseudo-obstruction (Ogilvie syndrome, distension of the cecum and colon without mechanical obstruction). Colonoscopy can decompress pseudo-obstruction and prevent cecal perforation. Treatment of LBO includes aggressive hydration, broad-spectrum antibiotics, and a surgical consultation. Emergent surgical indications include perforation or ischemia. Nonemergent indications include increasing abdominal distension and failure to resolve with conservative management.

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Small Bowel Obstruction

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SBO presents similarly to LBO, except that the patient typically has a history of prior abdominal surgeries. It is usually caused by adhesions, malignant obstruction, hernias, IBD strictures, or radiation-induced strictures. SBO complications include bowel infarction, perforation, peritonitis, and sepsis. Plain x-rays of the abdomen may show 2 or more air-fluid levels or dilated loops of bowel proximal to the obstruction (>2.5 cm diameter of small bowel). Complete obstruction is unlikely if air is seen in the rectum or in the colon. CT scan of ...

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