Usefulness of Ultrasound in the Diagnosis of Intestinal Anisakiasis.

Objectives: To evaluate the ultrasound (US) findings of gastrointestinal anisakiasis and the utility of US in its early diagnosis.

Methods: We retrospectively assessed the imaging findings and clinical data of 21 patients with gastrointestinal anisakiasis. Diagnosis was confirmed by a positive antigen (n = 16), endoscopy (n = 2), or a compatible clinical presentation, physical examination, and history of raw fish consumption (n = 3). Ultrasound findings reviewed included segmental circumferential bowel wall thickening, segmental edema of the valvulae conniventes, dilated small bowel loops with hyperperistalsis or hypoperistalsis, free fluid, and color Doppler hyperemia.

Results: Segmental circumferential bowel wall thickening was present in all 21 patients, whereas segmental edema of the valvulae conniventes was visualized in 13 patients, moderately dilated small-bowel loops proximal to the affected segment with increased peristalsis in 14 patients, small-to-moderate ascites in 18 patients, and color Doppler hyperemia in 7 patients. The US evaluation ruled out a surgical pathologic examination in all patients, and the diagnosis of anisakiasis was suggested by the radiologist on the basis of US findings in 12 patients.

Conclusions: Familiarity with the suggestive US presentation of intestinal anisakiasis may allow the radiologist to propose the diagnosis of this overlooked cause of abdominal pain and may also prompt an investigation of recent raw or lightly cooked seafood ingestion. Ultrasound findings of bowel wall thickening, especially segmental edema of the valvulae conniventes, hyperperistalsis, and dilatation of small-bowel loops proximal to the affected segment, ascites, and color Doppler hyperemia, along with a history of raw fish ingestion should aid the radiologist in the diagnosis of anisakiasis.