Acute invasive small-bowel Anisakiasis: clinical and CT findings in 19 patients

To evaluate the clinical and CT findings in patients with small-bowel Anisakiasis.

Nineteen patients with small-bowel Anisakiasis and who underwent abdominal CT between 2005 and 2012 were enrolled in our study. All of these patients were diagnosed using either a serologic test for Anisakiasis (n = 18) or by pathology (n = 1). Their medical records were reviewed in order to determine the clinical findings. CT images were retrospectively reviewed by two radiologists to evaluate the characteristics of the involved bowel wall and the ancillary findings.

All patients had presented with the acute onset of severe abdominal pain as well as a history of having recently eaten raw fish. The mean time interval from eating the fish to the onset of abdominal pain was 1.7 days. Eighteen patients were treated conservatively and experienced resolution of their symptoms within seven days of hospitalization. One patient underwent surgical exploration for presumed small-bowel ischemia. The sites of involvement included the ileum (16/19, 84%) and jejunum (3/19, 16%). All patients had circumferential bowel-wall thickening (mean, 0.8 cm) with an intermediate length of involved bowel (mean, 7.9 cm). Small-bowel obstruction occurred in 16 patients (84%). The target sign was present in 17 patients (89%), ascites, particularly in the perilesional area, in 16 patients (84%), and mesenteric edema in 15 patients (79%).

Small-bowel Anisakiasis should be considered in the differential diagnosis of acute abdomen in order to avoid unnecessary surgery when patients present with abdominal pain after having recently eaten raw fish, concentric bowel-wall thickening with the target sign in the ileum, perilesional ascites, as well as bowel obstruction seen on CT.