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Differential diagnosis small bowel obstruction
Indications for operation: early versus late postoperative period
Laparoscopic versus open approach
Bowel resection
From Townsend CM: Sabiston Textbook of Surgery, 19th edition (Saunders 2012)
Most patients with small bowel obstruction are classified as having simple obstructions that involve mechanical blockage of the flow of luminal contents without compromised viability of the intestinal wall. In contrast, strangulation obstruction, which usually involves a closed loop obstruction in which the vascular supply to a segment of intestine is compromised, can lead to intestinal infarction. Strangulation obstruction is associated with an increased morbidity and mortality risk, and therefore recognition of early strangulation is important. In differentiating from simple intestinal obstruction, classic signs of strangulation have been described; these include tachycardia, fever, leukocytosis, and a constant, noncramping abdominal pain. However, a number of studies have convincingly shown that no clinical parameters or laboratory measurements can accurately detect or exclude the presence of strangulation in all cases.
CT examination is useful only for detecting the late stages of irreversible ischemia (e.g., pneumatosis intestinalis, portal venous gas). Various serum determinations, including lactate dehydrogenase, amylase, alkaline phosphatase, and ammonia levels, have been assessed with no real benefit. Initial reports have described some limited success in discriminating strangulation by measuring serum d -lactate, creatine phosphokinase isoenzyme (particularly the BB isoenzyme), or intestinal fatty acid–binding protein; however, these are only investigational and cannot be widely applied to patients with obstruction. Finally, noninvasive determinations of mesenteric ischemia have been described using a superconducting quantum interference device (SQUID) magnetometer to detect mesenteric ischemia noninvasively. Intestinal ischemia is associated with changes in the basic electrical rhythm of the small intestine. This technique remains investigational and is not in widespread clinical use.
Thus, it is important to remember that bowel ischemia and strangulation cannot be reliably diagnosed or excluded preoperatively in all cases by any known clinical parameter, combination of parameters, or current laboratory and radiographic examinations.
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