Ultrasonographic appearance of Ascaris lumbricoides in the small bowel

Roundworm infestation, one of the most common helminthic diseases worldwide , is caused by Ascaris lumbricoides, one of the largest parasites that infe sts the human bowel. A lumbricoides is virtually universal at some stage of childhood in semitropical and tropical regions. This study describes our e xperience with the ultrasonographic appearance of intestinal ascariasis in 84 patients, 2.5 to 42 years of age, examined over 2 years beginning Octobe r 1997. The patients' conditions ranged from acute intestinal obstruction t o no clinical features pertaining to obstruction. Ultrasonographic examinat ion was performed with an Echocee power Doppler real-time unit with a varia ble-frequency 3.7-MHz convex, 7.5MHz linear probe. In longitudinal section the Ascaris worm presented as a linear intraluminal mass with 3 or 4 linear echogenic interfaces; in the cross section, it was round, sometimes appear ing as a "target" sign. Some worms also showed serpentine movements. Sonogr aphic examination of the patients in the left lateral decubitus position af ter ingestion of water improved detection and visualization of the worms in some cases. It is concluded that A lumbricoides in the small bowel has a s onographic appearance that can be recognized by the wary observer.