Intestinal anisakiasis: CT imaging findings-a 10-year descriptive study in a single center.

PURPOSE: The aim of this study was to retrospectively review cases of intestinal anisakiasis diagnosed by CT over a 10-year period and to evaluate imaging findings associated with the disease. METHODS: This retrospective study included 71 patients with clinical suspicion of intestinal anisakiasis in whom an abdominopelvic computed tomography (CT) was performed at a single institution between June 2011 and December 2021. To identify the cases, we used medical term search engines and the hospital's radiology case database. Clinical information was gathered from the medical records. A radiologist with five years of experience reviewed and analyzed the CT images to determine the characteristic findings of intestinal anisakiasis. RESULTS: The study included 47 confirmed cases of intestinal anisakiasis. The mean age of the patients was 52 years (range 18-87 years), being more frequent in men than women (26:21). All patients reported ingestion of raw fish, most commonly anchovies in vinegar (30/47, 63,8%). Abdominal pain was the predominant symptom, accompanied by nausea, vomiting, and occasionally fever. The most common clinical suspicions were intestinal obstruction (14/47, 29,8%) and appendicitis (10/47, 21,3%), whereas intestinal anisakiasis was suspected in only 2 cases prior to imaging. CT showed thickening of the bowel wall with submucosal edema in all patients, predominantly involving the ileum (43/47, 91,5%), usually in a relatively long segment (mean of 17,5 cm, range 10-30 cm). Simultaneous involvement of multiple bowel segments was observed in 16 cases (34%). Intestinal obstruction with dilatation of proximal loops (33/47, 70,2%), ascites (45/47, 95,7%), and mesenteric fat striation (32/47, 68,1%) were also common findings. CONCLUSION: This study demonstrates the value of computed tomography in suggesting the diagnosis of intestinal anisakiasis, which often presents with nonspecific clinical manifestations. The characteristic CT findings that provide diagnostic clues are bowel wall thickening with submucosal edema, typically involving a long segment of the ileum, with signs of intestinal obstruction, ascites, and mesenteric fat striation. Simultaneous involvement of several intestinal segments (typically the gastric antrum and right colon) is an additional finding to be considered and may provide a diagnostic clue.

Anisakiasis: Imaging findings.

OBJECTIVE: To review the main findings for anisakiasis in the different imaging tests that can be used to diagnose it, based on studies done at our center. CONCLUSION: The presence of Anisakis species in food consumed in Western countries is becoming more common. Patients with anisakiasis present with acute abdomen; there are no specific clinical signs or laboratory findings. Careful history taking is key to discovering exposure to Anisakis-contaminated food, but this task is hindered by unfamiliarity with the condition and lack of suspicion and is also confounded by the variable latency period after ingestion of Anisakis-contaminated food. Give the nonspecific presentation, patients with anisakiasis often undergo imaging tests to rule out other processes. Thus, radiologists need to be familiar with the spectrum of imaging findings that should lead to the inclusion of anisakiasis in the differential diagnosis, so they can guide clinicians toward directed history taking and specific tests.

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.

Imaging in gastric anisakiasis.

Gastrointestinal anisakiasis is an uncommon zoonotic parasitic infection caused by consumption of raw or undercooked seafood infected with nematodes of genus Anisakis. Given the non-specific clinical presentation of acute abdomen, nausea, and vomiting these patients are often subject to radiologic imaging. We present ultrasound and computed tomography imaging features in a case of gastric anisakiasis demonstrating characteristic features of diffuse gastric submucosal edema, perigastric stranding and trace ascites that helped to further elaborate the clinical history of uncooked fish consumption prompting timely endoscopic diagnosis and management.

A case of small intestinal intussusception caused by anisakiasis diagnosed and treated by upper gastrointestinal endoscopy.

A 35-year-old man attended our hospital with complaining of epigastric pain and vomiting. He was diagnosed with bowel intussusception based on the target sign revealed in the upper jejunum by abdominal computed tomography. However, the cause of the intussusception was not clear. Insertion of an endoscope into the jejunum revealed prominent edema in the upper part of the jejunum, and Anisakis simplex was identified at the site and removed. Symptoms rapidly improved after endoscopic treatment. We report this case because surgery was avoidable and because we are aware of no previous reports of small intestinal intussusception caused by anisakiasis that has been diagnosed and treated endoscopically.

Distinguishing gastric anisakiasis from non-anisakiasis using unenhanced computed tomography.

PURPOSE: This study aimed to assess the diagnostic performance of unenhanced computed tomography (CT) for distinguishing gastric anisakiasis from non-anisakiasis gastric conditions and the reproducibility of CT findings. METHODS: Fifty-six anisakiasis and 74 non-anisakiasis cases with gastric wall thickening on urgent observation using unenhanced CT were included. Using a κ analysis, two radiologists independently assessed the reproducibility of CT findings, including "circumferential gastric wall thickening," "gastric wall thickening extending more than two segments," "bulky and low-density gastric wall thickening," "increase in peri-gastric fat density," and "ascites." An anisakiasis diagnostic score (ADS) was developed for this study and was used to quantitatively evaluate the CT findings. An anisakiasis diagnostic prediction (ADP) with an appropriate cutoff value was used to further evaluate the ADS. Two radiologists reassessed the findings in consensus to determine the sensitivity, specificity, and accuracy of the CT findings, including the ADP and ADS area under the curve (AUC). RESULTS: Considering reproducibility, a substantial agreement (0.6 < κ < 0.8) was achieved for all findings except "circumferential gastric wall thickening" (κ = 0.499), whereas for diagnostic performance, all findings except ascites were significantly more frequent among the anisakiasis cases. "Bulky and low-density gastric wall thickening" had the highest sensitivity (98%), whereas "gastric wall thickening extending more than two segments" had the highest specificity (80%). The ADP sensitivity, specificity, and accuracy were 91%, 84%, and 87%, respectively. The AUC was 0.902 (p < 0.05). CONCLUSIONS: Unenhanced CT findings are useful for distinguishing anisakiasis from non-anisakiasis gastric conditions with sufficient reproducibility.

Anisakiasis and intestinal endometriosis: under-recognized conditions in the differential diagnosis of acute abdomen.

Anisakiasis and endometriosis is rare cause of intestinal obstruction and even perforation, the latter being extremely rare. We report the case of a patient with intestinal obstruction that progress to perforation and whose differential diagnosis is complex. The interest in this clinical case lies in the unexpected histology of the surgical specimen after the intervention of the patient, because the intestinal endometriosis as intestinal anisakiasis are rare entities that make diagnosis difficult.

Direct parasitologial diagnosis of infection with Hysterothylacium aduncum in a patient with epigastralgia.

Anisakis parasitization has been on the rise because some factors, like increased interest in dishes consisting of raw fish. We report a case of epigastralgia with direct diagnosis by endoscopy, which futher study pointed out H. Aduncum as causal agent, a anisakis which is rarely involved in human anisakiasis.

Mesenteric tumor due to chronic anisakiasis.

Intestinal anisakiasis is a rare parasitic disease and difficult to diagnose due to symptoms are not specific, so it is considered an underdiagnosed disease. The clinical suspicion with a correct diagnosis of anisakiasis allows the establishment of a correct treatment; in most cases, the resolution is possible with conservative treatment, avoiding unnecessary surgery to the preoperative differential diagnosis of acute abdomen. We report the case of apatient who required urgent surgery secondary to an exacerbation of chronic anisakiasis.

Sonographic diagnosis of intestinal anisakiasis presenting as small bowel obstruction.

BACKGROUND: To evaluate the accuracy of ultrasonography (US) in the diagnosis of intestinal anisakiasis presenting as small bowel obstruction. METHODS: We retrospectively reviewed the clinical features, US examinations, and CT scans of seven patients with intestinal anisakiasis presenting as small bowel obstruction. We compared the performances of US and CT in demonstrating peritoneal fluid, small bowel dilatation, and segmental edema of Kerckring's folds. RESULTS: All patients presented with a history of ingesting raw saltwater fish or squid less than 2 days prior to presentation at the emergency department and had significant levels of Anisakis-specific IgE. Both US and CT revealed small bowel obstruction, with dilated small bowel in all patients and accumulations of free peritoneal fluid in six patients. CT showed segmental wall thickening and luminal narrowing with submucosal edema distal to the distended small bowel; US did so in four patients. CONCLUSIONS: Although US was inferior to CT in demonstrating the segmental intestinal edema causing small bowel obstruction, it can be applied in suspected cases of intestinal anisakiasis presenting as small bowel obstruction, particularly where CT is unavailable or there are concerns about radiation exposure.

Anisakiasis presenting to the ED: clinical manifestations, time course, hematologic tests, computed tomographic findings, and treatment.

BACKGROUND: The prevalence of anisakiasis is rare in the United States and Europe compared with that in Japan, with few reports of its presentation in the emergency department (ED). This study describes the clinical, hematologic, computed tomographic (CT) characteristics, and treatment in gastric and small intestinal anisakiasis patients in the ED. METHODS: We retrospectively reviewed the data of 83 consecutive anisakiasis presentations in our ED between 2003 and 2012. Gastric anisakiasis was endoscopically diagnosed with the Anisakis polypide. Small intestinal anisakiasis was diagnosed based on both hematologic (Anisakis antibody) and CT findings. RESULTS: Of the 83 cases, 39 had gastric anisakiasis and 44 had small intestinal anisakiasis based on our diagnostic criteria. Although all patients had abdominal pain, the gastric anisakiasis group developed symptoms significantly earlier (peaking within 6 hours) than the small intestinal anisakiasis group (peaking within 48 hours), and fewer patients with gastric anisakiasis needed admission therapy (5% vs 57%, P<.01). All patients in the gastric and 40 (91%) in the small intestinal anisakiasis group had a history of raw seafood ingestion. Computed tomographic findings revealed edematous wall thickening in all patients, and ascites and phlegmon of the mesenteric fat were more frequently observed in the small intestinal anisakiasis group. CONCLUSIONS: In the ED, early and accurate diagnosis of anisakiasis is important to treat and explain to the patient, and diagnosis can be facilitated by a history of raw seafood ingestion, evaluation of the time-to-symptom development, and classic CT findings.

PET/CT findings in acute gastric anisakiasis.

Acute gastric anisakiasis is caused by the consumption of raw or undercooked fish containing Anisakis larvae. Although several reports have demonstrated the CT features of acute gastric anisakiasis, little is known about the FDG PET/CT findings. We report a 59-year-old woman who underwent FDG PET/CT and was finally diagnosed as having acute gastric anisakiasis. The PET/CT demonstrated focal FDG accumulation in the fornix of the gastric wall and lymph nodes in the lesser curvature and paraaortic regions.

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

PURPOSE: To evaluate the clinical and CT findings in patients with small-bowel Anisakiasis. MATERIALS AND METHODS: 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. RESULTS: 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%). CONCLUSION: 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.

CT findings of gastric and intestinal anisakiasis.

PURPOSE: To illustrate the CT findings of gastrointestinal anisakiasis. SUBJECTS AND METHODS: The Institutional Review Board approving this retrospective study waived the requirement for informed consent. Review of our emergency department's clinical records from September 2008 to January 2012 identified 41 consecutive patients who were diagnosed with gastrointestinal anisakiasis. 20 patients were diagnosed with gastric anisakiasis with endoscopically proven Anisakis larvae, and 21 patients were diagnosed with intestinal anisakiasis with positive test results for anti-anisakidae antibody and the presence of intestinal lesions on CT. Two radiologists retrospectively assessed the CT findings. RESULTS: The mean time delay from raw fish ingestion to symptom onset was 5.2 h (range 0.5-24 h) in gastric anisakiasis and 39 h (range 12-120 h) in intestinal anisakiasis. Gastric anisakiasis showed marked submucosal edema of the gastric wall (20/20 patients, 100%), increased attenuation of adjacent fat (19/20, 95%), and ascites (14/20, 70%) on CT. Intestinal anisakiasis showed marked submucosal edema of the intestine (21/21 patients, 100%) without showing complete intraluminal occlusion, ascites (21/21, 100%), increased attenuation of adjacent fat (19/21, 90%), and fluid collection in the distal segment of the constricted small intestine (13/21, 62%) on CT. CONCLUSION: Severe submucosal edema with ascites is a characteristic finding of gastrointestinal anisakiasis when compared with other forms of gastroenteritis. When CT shows the typical findings of gastrointestinal anisakiasis, radiologists may suggest the possibility of clinically undiagnosed anisakiasis, especially in intestinal anisakiasis as the diagnosis is sometimes difficult due to the long interval between food intake and symptom onset.

Acute intestinal anisakiasis: CT findings.

Small bowel anisakiasis is a relatively uncommon disease that results from consumption of raw or insufficiently pickled, salted, smoked, or cooked wild marine fish infected with Anisakis larvae. We report a case of intestinal anisakiasis in a 63-year-old woman presenting with acute onset of abdominal complaints one day after ingestion of raw wild-caught herring from the Northsea. Computed tomography (CT) scanning demonstrated thickening of the distal small bowel wall, mucosa with hyperenhancement, mural stratification, fluid accumulation within dilated small-bowel loops and hyperemia of mesenteric vessels. In patients with a recent history of eating raw marine fish presenting with acute onset of abdominal complaints and CT features of acute small bowel inflammation the possibility of anisakiasis should be considered in the differential diagnosis of acute abdominal syndromes.

Computed tomographic features of two cases of acute gastric anisakiasis.

Little is known about the detailed computed tomography (CT) features of acute gastric anisakiasis. Our two cases showed transiently swollen gastric folds comprised of the remarkably thickened contrast little-enhanced submucosal layer with little-thickened contrast-enhanced mucosal and muscular-serosal layers on multi-detector row CT. When CT demonstrates the swollen gastric folds in acute abdomen, acute gastric anisakiasis should be included in the differential diagnosis.