Individual worms are seen as longitudinal tubular structures. If the alimentary tract of the worm is empty, the worm may appear as a filling defect. If its alimentary tract is distended, the worm appears as parallel bands (arrow). On transverse sections, the worm appears as a target sign (arrowhead) with body wall and a central dot representing its gut.
Reference: DiSantis DJ, Ralls PW, Balfe DM, et al: The patient with suspected small bowel obstruction: imaging strategies. American College of Radiology. ACR Appropriateness Criteria. Radiology 2000 Jun; 215(suppl): 121-4
Credit: Dr Abhijit Datir