Usefulness of Ultrasound in the Diagnosis of Intestinal Anisakiasis

First Case of Human Anisakiosis in Greece: Acute Invasive Infection Mimicking Peritoneal Malignancy

Consumption of raw and mildly processed seafood, in the context of modern Western world eating trends, is recognized as a major driver for human fish-borne infections. However, these zoonoses and their unfamiliar risks remain neglected and underappreciated among European diagnosticians. In contemporary Europe anisakidosis is one of the most important fish-borne zoonoses. It is caused by ingesting the third-stage infective larvae of the nematode parasites that belong to the family Anisakidae. The case described herein, is an intestinal and ectopic form of anisakiosis (Anisakis spp.), causing symptoms of subacute abdomen and masquerading as an intraperitoneal malignancy. It is the first anisakidosis case reported in Greece, affecting a young patient who had been repeatedly exposed to the parasite by consuming homemade raw fish. Right hemicolectomy, omentectomy and excision of a descending colon nodule were uneventfully performed. The pathology report confirmed granulomatous tissue with eosinophilic infiltration and parasites that were morphologically and molecularly identified as Anisakis spp. Although challenging, acquiring an accurate diagnosis of anisakidosis can prevent unnecessary surgery, as the infection typically is self-resolving, and if treatment is deemed necessary, it can be limited to antiparasitic medication. However, in rare cases, extra-gastrointestinal migration of larvae can cause severe damage with practically unknown risks, posing a diagnostic and therapeutic dilemma. In such a clinical case scenario, surgical exploration can decisively contribute to a definitive diagnosis and early identification of intraabdominal complications necessitating surgical intervention.

Evaluation of imaging findings in gastrointestinal anisakiasis in emergency CT and ultrasound

BACKGROUND

To assess the frequency of appearance of various signs (isolated and grouped) in emergency imaging tests in patients with anisakiasis, according to the location of gastrointestinal tract involvement.

METHODS

Retrospective review by two experienced radiologists of emergency ultrasounds and CTs performed on patients admitted in the Emergency Department of our hospital with later confirmed anisakiasis (2010-2021), assessing the presence of signs suggesting anisakiasis. Calculation of the frequency of appearance according to the gastric or intestinal location, as well as the most common grouped signs.

RESULTS

Out of 231 total patients with anisakiasis, imaging studies were performed in 144: abdominopelvic ultrasound in 43 cases and CT in 111 (both techniques in 31). In cases with gastric occurrence (34), in CT the wall stratification (100%), wall thickening (97%), fat stranding (91%) and ascitic fluid (82%) were predominant. In the intestinal cases (105), in CT (95) the wall thickening (100%), fat stranding (92%) and mesenteric vessel engorgement (83%) were usual; in ultrasound (40), ascitic fluid and wall thickening (70% in both cases) were frequently observed. The frequency of grouped appearance of the mentioned signs was 82% in gastric cases, 80% in intestinal cases and 50% in ultrasounds. Multisegment involvement in CT reached 28% (gastric + intestinal) and 11% (only intestinal) of cases.

CONCLUSIONS

The most frequent CT findings in patients with gastric anisakiasis are wall stratification and thickening, fat stranding and ascitic fluid. In the intestinal cases, wall thickening, fat oedema and vessel engorgement are the most often observed findings.

CRITICAL RELEVANCE STATEMENT

The presence of different radiological signs makes it advisable to include anisakiasis in the differential diagnosis of acute abdomen. Intestinal and multifocal involvement rates are greater than previously reported.

KEY POINTS

• In gastric anisakiasis, CT frequently shows wall stratification and thickening, fat stranding and ascitic fluid. • In intestinal anisakiasis, CT often presents wall thickening, fat stranding and vessel engorgement. • In intestinal anisakiasis, ultrasounds most frequently show ascitic fluid and wall thickening.

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.

Reconstruction Algorithm-Based Ultrasonic and Spiral CT Images in Evaluating the Effects of Dexmedetomidine Anesthesia for Acute Abdomen

OBJECTIVE

The study focused on the application value of iteration reconstruction algorithm-based ultrasound and spiral computed tomography (CT) examinations, and the safety of dexmedetomidine anesthesia in acute abdominal surgery.

METHODS

80 cases having the acute abdomen surgery were selected as the research subjects. They were divided into group A (40 cases) and group B (40 cases) according to the anesthetic drugs used in the later period. The experimental group was injected with propofol, remifentanil, and atracurium combined with dexmedetomidine; the control group was injected with propofol, remifentanil, and atracurium only. After the operation, the patient was for observed for the pain, agitation, adverse reactions, heart rate (HR), and blood pressure. All patients received ultrasound and spiral CT examinations, and based on the characteristics of the back-projection algorithm, an accelerated algorithm was established and used to process the image, and according to which, the patient's condition and curative effects were evaluated.

RESULTS

After image reconstruction, the ultrasound and spiral CT images were clearer with less noise and more prominent lesions than before reconstruction. Before image reconstruction, the accuracy rates of ultrasound and spiral CT in diagnosing acute abdomen were 92.3% and 91.1%, respectively. After reconstruction, the corresponding numbers were 96.3% and 98.1%, respectively. After reconstruction, the accuracy of the two methods in diagnosing acute abdomen was significantly improved compared with that before reconstruction, and the difference was statistically significant (P < 0.05). The Ramsay score of the experimental group was significantly higher than that of the control group at each time period, P < 0.05; the agitation score and visual analogue scale (VAS) score of the experimental group were significantly lower than the control group at each time period after waking up, P < 0.05.

CONCLUSION

Reconstruction algorithm-based ultrasound and spiral CT images have high application value in the diagnosis of patients with acute abdomen, and dexmedetomidine has good safety in anesthesia surgery.

Diagnostic approach to small-bowel wall thickening: Beyond Crohn's disease and cancer

Although small-bowel wall thickening is a common manifestation of Crohn's disease and tumors, many other entities can give rise to similar imaging findings. The small bowel is difficult to access by endoscopy, so radiologic imaging tests play an essential role in the diagnosis of conditions involving the small bowel. The main objectives of this paper are to explain the definition of small-bowel wall thickening, analyze the patterns of involvement seen in multidetector computed tomography (MDCT) with intravenous contrast administration, and provide an image-based review of the different causes of small-bowel wall thickening. The differential diagnosis must include many entities because wall thickening can result from immune-mediated, infectious, or vascular causes, as well as from toxicity and other lesser-known entities. As the imaging appearance of many of these conditions overlap, clinical and laboratory findings are necessary to support the imaging diagnosis.

Anisakiasis of the Terminal Ileum Removed by Colonoscopy

A 35-year-old Japanese man with no significant medical history presented to the emergency department complaining of abdominal pain, nausea, and vomiting 35 h after ingesting raw horse mackerel, sardines, and tuna. Computed tomography of the abdomen with intravenous contrast revealed significant thickening of the terminal ileum with mild proximal dilatation and moderate ascites. On colonoscopy, an actively moving anisakis larva was discovered in the terminal ileum. The larva was removed with endoscopic forceps. The patient's symptoms resolved quickly following the procedure.

Diagnostic approach to small-bowel wall thickening: beyond Crohn's disease and cancer

Although small-bowel wall thickening is a common manifestation of Crohn's disease and tumors, many other entities can give rise to similar imaging findings. The small bowel is difficult to access by endoscopy, so radiologic imaging tests play an essential role in the diagnosis of conditions involving the small bowel. The main objectives of this paper are to explain the definition of small-bowel wall thickening, analyze the patterns of involvement seen in multidetector computed tomography (MDCT) with intravenous contrast administration, and provide an image-based review of the different causes of small-bowel wall thickening. The differential diagnosis must include many entities because wall thickening can result from immune-mediated, infectious, or vascular causes, as well as from toxicity and other lesser-known entities. As the imaging appearance of many of these conditions overlap, clinical and laboratory findings are necessary to support the imaging diagnosis.

Intestinal anisakiasis with severe intestinal ischemia caused by extraluminal live larvae: a case report

Background

Anisakiasis is a parasitic infection caused by Anisakis worms found in raw fish. Most cases of anisakiasis occur in the stomach and rarely occur in the intestine. It is extremely rare for live larvae to break through the intestine into the mesentery and cause severe intestinal ischemia. Anisakiasis can be treated conservatively, because the larvae will die in approximately 1 week, but, sometimes, a serious condition can arise, as in this case. We report the first case of extraluminal anisakiasis in which a live Anisakis worm caused severe intestinal ischemia.

Case presentation

The patient was a 26-year-old woman who ate squid a week prior. She had abdominal pain and was admitted to our emergency department. On physical examination, abdominal guarding and rebound tenderness were present in her lower abdomen. Contrast-enhanced computed tomography showed ascites, the whirl sign, localized submucosal edema of the intestinal wall, and a dilated small bowel segment with edema. We suspected the strangulated small bowel obstruction based on the CT-scan findings. To rule out the strangulated small bowel obstruction, laparoscopic exploration was performed. Bloody ascites in the pouch of Douglas and severe inflammation in 20 cm of the ileum were observed. An Anisakis larva had perforated the intestinal wall and was found alive in the mesentery. The ileum had developed a high degree of ischemia, so the affected section was resected. Histopathological examination revealed that the Anisakis worm body was in the inflamed mesentery and caused a high degree of ischemia in the intestinal tract. The patient was discharged 9 days after surgery.

Conclusions

A living Anisakis larva punctured the mesentery of the small intestine, resulting in severe intestinal ischemia. As seen in this case, intestinal anisakiasis may cause serious symptoms, and a low threshold for performing diagnostic laparoscopy for the early diagnosis of bowel ischemia secondary to anisakiasis can be useful in determining the definite diagnosis and indications for resection.