Intestinal Ascariasis

Author: Santip Srisuwan, M.D.

Axial CT image shows multiple tubular filling defects (arrows) within the opacified lumen of the small bowel. Note contrast filling within the filling defects.

Facts:

• Most common helminthic infection (worldwide prevalence 25%)
• Usually asymptomatic.
• Possible symptoms are colicky abdominal pain in adults and growth retardation/intussusception/volvulus in children

Imaging

• X-ray: usually normal but may present as bowel obstruction (partial or complete), or soft tissue masses
• US: hypo echoic curvilinear tubular structures with well-defined echogenic walls and curling movement of the worm during the exam
• CT: long, thin tubular structure coiled within the small bowel, outlined by oral contrast materials

References:

1. Hommeyer SC, Hamill GS, Johnson JA. CT diagnosis of intestinal ascariosis. Abdom Imaging 1995;20:315-316.

2. Rodrigues EJ, Gama MA, Ornstein SM, et al. Ascariasis causing small bowel volvulus. Radiographics 2003;23:1291-3.

3. Villamizar E, Mendez M, Bonilla E, et al. Ascaris lumbricoides infestation as a cause of intestinal obstruction in children: experience with 87 cases. J Pediatr Surg 1996;3:201-4.

4. Hendi JM, Horton KM, Fishman EK. Ascariasis infection of the colon: MDCT evaluation. Emerg Radiol 2006;12:180-1.

5. Bude RO, Bowerman RA. Case 20: Biliary ascariasis. Radiology 2000;214:844-7.

6. Hershkovitz D, Wasserberg N. Large bowel obstruction due to Ascaris lumbricoides. IMAJ 2004;6:115-116.