Diagnosis of small bowel obstruction: the contribution of diagnostic ultrasound

The hallmark of intestinal obstruction, whether due to a mechanical cause or to absence of peristalsis, is the intraluminal accumulation of fluid. The presence of air simply makes it easier to visualize dilated fluid-filled loops of plain radiographs. When gas is absent, secondary to vomiting or to cessation of air swallowing, the fluid-filled loops may be difficult to identify. In closed loop obstruction, air cannot enter the involved bowel, and in this situation sonography may provide important information concerning the status of the intestinal tract. In nonstrangulating obstruction, sonography offers confirmatory evidence of dilated fluid-filled loops of bowel. In some instances, ultrasonography may correctly identify the gastrointestinal tract origin of a problem thus enabling appropriate management of the patient. We describe three patients in whom ultrasound enabled prompt diagnosis of fluid-filled loops.