However, imaging and laboratory findings that suggest a higher grade SBO with a complication, such as ischemia, closed-loop obstruction, volvulus, or complete obstruction, may prompt more urgent surgical treatment. Patients with high-grade SBO may present with more severe abdominal pain, as well as a higher risk of bowel ischemia and perforation. However, physical examination and laboratory tests are neither sufficiently sensitive nor specific to determine which patients with SBO have coexistent strangulation or ischemia. Early imaging diagnosis and intervention is therefore critical for successful treatment and minimization of mortality, which can be as high as 25% in the setting of ischemia. The goals of imaging in high-grade SBO are to evaluate the severity of the obstruction, identify the etiology/site of the obstruction, and to detect the presence of complications, such as volvulus, strangulation, closed-loop obstruction, and ischemia. Specific imaging signs that suggest ischemia include abnormally decreased or increased bowel wall enhancement, intramural hyperdensity on noncontrast CT, bowel wall thickening, mesenteric edema, ascites, and pneumatosis or mesenteric venous gas. The presence of ischemia warrants immediate surgery. CT Abdomen and Pelvis Multiple publications have confirmed the use and accuracy of a standard abdominal and pelvic CT examination in patients with a suspected high-grade SBO. A diagnostic accuracy of more than 90% has been reported [4,5,17], with high accuracy for distinguishing SBO from an adynamic small-bowel ileus [6], and for identifying the cause of obstruction [17-20]. Patients with a suspected high-grade obstruction do not require any oral contrast medium because the nonopacified fluid in the bowel provides adequate intrinsic contrast.
Suspected Small Bowel Obstruction. However, imaging and laboratory findings that suggest a higher grade SBO with a complication, such as ischemia, closed-loop obstruction, volvulus, or complete obstruction, may prompt more urgent surgical treatment. Patients with high-grade SBO may present with more severe abdominal pain, as well as a higher risk of bowel ischemia and perforation. However, physical examination and laboratory tests are neither sufficiently sensitive nor specific to determine which patients with SBO have coexistent strangulation or ischemia. Early imaging diagnosis and intervention is therefore critical for successful treatment and minimization of mortality, which can be as high as 25% in the setting of ischemia. The goals of imaging in high-grade SBO are to evaluate the severity of the obstruction, identify the etiology/site of the obstruction, and to detect the presence of complications, such as volvulus, strangulation, closed-loop obstruction, and ischemia. Specific imaging signs that suggest ischemia include abnormally decreased or increased bowel wall enhancement, intramural hyperdensity on noncontrast CT, bowel wall thickening, mesenteric edema, ascites, and pneumatosis or mesenteric venous gas. The presence of ischemia warrants immediate surgery. CT Abdomen and Pelvis Multiple publications have confirmed the use and accuracy of a standard abdominal and pelvic CT examination in patients with a suspected high-grade SBO. A diagnostic accuracy of more than 90% has been reported [4,5,17], with high accuracy for distinguishing SBO from an adynamic small-bowel ileus [6], and for identifying the cause of obstruction [17-20]. Patients with a suspected high-grade obstruction do not require any oral contrast medium because the nonopacified fluid in the bowel provides adequate intrinsic contrast.