CT in abdominal and pelvic trauma.

Computed tomography (CT) is valuable in the evaluation of the abdomen and pelvis in victims of blunt trauma and stab wounds to the back if their condition is stable or if results of their physical examination are unreliable (eg, due to altered mental status). The appearance of blood at CT depends on window width, hematocrit, physical state of blood, use of intravenous contrast material, and attenuation of adjacent organs. Rapid infusion of contrast material improves visualization of hematoma. CT is most useful in evaluating injuries to the spleen, liver, pancreas, kidney, duodenum, and small and large bowel. Although CT can be accurate in demonstrating lacerations and hematoma, radiologists must beware of pitfalls in the CT diagnosis of splenic injuries (normal lobulation or cleft within the spleen, elongation of the left hepatic lobe, adjacent unopacified bowel loop, previous splenic infarct), hepatic injuries (beam-hardening artifact from adjacent ribs, air-contrast level in the stomach), and pancreatic injuries (streak artifacts from nasogastric tubes, folding of the pancreas, misinterpretation of adjacent structures, pancreatic contusion or hematoma, intrinsic elasticity of the pancreas). Delayed scanning or scanning with slow infusion rates may also obscure hematoma. Knowledge of the various appearances of the posttraumatic abdomen and pelvis on CT scans is essential for prompt and effective treatment of patients.