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CASE SCENARIO

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An 84-year-old woman with a history of Parkinson’s disease presents to the emergency department with mental status changes and progressive abdominal distension. She is currently staying in a group home and is accompanied by her caretaker. She is unable to give a clear history, but her caretaker notes that she has had previous similar episodes of distension that have always spontaneously resolved. She regularly requires docusate, magnesium citrate, and polyethylene glycol to control her constipation.

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On examination, the patient is afebrile with normal vital signs. Her abdomen is nontender, but notably distended with a palpable mass in the left lower quadrant. There is no palpable abnormality on rectal examination, although the rectal vault is empty. Her lab work is remarkable for a lactate of 2.1 and creatinine of 2.4, but no leukocytosis.

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EPIDEMIOLOGY

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Large-bowel obstruction is an uncommon surgical emergency. In Westernized nations, approximately 85% of patients with large-bowel obstruction present with colorectal carcinomas,1 and in fact malignant obstruction is the initial presentation of colon cancer in as many as 20% of colon cancer diagnoses.2 The remaining 10% to 15% of patients obstruct secondary to volvulus, diverticular stricture, or the less common causes listed in Table 10–1.3 Patient age and medical history can provide important clues as to the etiology of the disease, although large-bowel obstruction is most common among the elderly.4

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Colonic volvulus is most common among elderly nursing home patients due to a variety of factors, including excessive mobility of the colon, low fiber diet, chronic constipation, and lack of exercise. The sigmoid colon is the most common site of volvulus, representing 65% to 80% of cases of colonic volvulus and with a mean age of presentation of 70 years.3,5 Cecal volvulus represents the majority of remaining cases, with transverse colon or splenic flexure volvulus occurring in rare circumstances.

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Acute colonic pseudo-obstruction is a motility disorder characterized by massive colonic dilatation and is most common among patients with concurrent causative medical conditions, although rarely it can develop spontaneously. These patients have most commonly undergone recent operation, with trauma, orthopedic, and abdominal operations representing the majority of cases, but may be admitted for medical conditions as well. Narcotic, anticholinergic, or antidepressant therapies may be causative. Pseudo-obstruction may progress to perforation, with risk substantially increasing at cecal diameter between 9 and 12 cm, and when symptoms last greater than 6 days.6

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DIFFERENTIAL DIAGNOSIS

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Table Graphic Jump Location
Table 10–1Causes of Large-Bowel Obstruction

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