Sonographic diagnosis of bowel obstruction presenting with fluid-filled loops of bowel.

When intestinal obstruction presents with fluid-filled bowel loops instead of air-distended loops, subtle elongated masses representing these bowel loops may be missed on plain abdominal radiographs. In these cases, ultrasound will show sausage-shaped, cystic structures, with uneven margins representing mucosal folds, distributed throughout the abdomen and sometimes accompanied by peristalsis. These features differentiate fluid-filled bowel loops from other cystic structures in the abdomen and help make a diagnosis of bowel obstruction.