Teaching Case

A 40-year-old female patient presented to the emergency department complaining of moderate abdominal pain lasting for 3 days. Clinical examination revealed abdominal tenderness and an increased white blood cell count was found. The past medical history was unremarkable.

The patient was referred for CT examination of the abdomen. The solid abdominal viscera were unremarkable. However, note was made of a jejunal loop appearing focally thickened and with marked fat stranding of the adjacent mesenteric fat. After the intravenous administration of contrast medium there was enhancement of the thickened jejunal loop and normal opacification of the mesenteric vessels. A small linear hyperdense structure was identified on the thickened bowel wall which was visible also in the unenhanced scan, excluding the presence of contrast extravasation and raising suspicion of a foreign body, possibly a fishbone. (Fig. 1) Based on these findings and after being questioned by the surgeon, the patient admitted she had eaten fish the day the pain started. On surgery, a fishbone was detected impacted within the jejunal loop wall.

Fish bone ingestion accounts for up to 84% of all foreign bodies ingested accidentally. Most of the patients are asymptomatic, but some of them present to the emergency department some days later with pain, swelling or complications such as perforation. Fortunately these complications affect only 1% of patients. Some patients may complain of bizarre clinical manifestations like ureteric colic and bowel bleeding. The unspecific nature of symptoms makes clinical diagnosis of foreign body ingestion difficult, necessitating imaging diagnosis [1]. Predisposing factors of unwilling fishbone ingestion include old age, alcohol consumption, mental retardation and rapid eating [2].
Fish bones can be impacted in any part of the gastrointestinal tract, but most commonly into the pharynx and the oral cavity, specifically at the base of the tongue and the tonsils. The commonest sites of impaction and perforation include the cricopharyngeus muscle at the level of C5/C6, and sites with the least motion and maximal angulation such as ileus and recto-sigmoid junction. The esophagus’ poor vascularity and absence of adventitia explain the increased frequency of perforation observed at this site. Pneumoperitoneum is rare because of the gradual erosion of the bowel wall leading to its bounding by surrounding omentum and fibrin. Clinical presentation may be more striking in the case of complications like bowel obstruction, abscess or fistula with the trachea and great vessels Formation [1, 2]. Rarely, fish bones can be found in the bronchial tree, commonly impacted into the right bronchus as other accidentally ingested foreign bodies, causing atelectasis and pneumonia due to the obstruction [1].
Oral cavity examination is the first step in the management of the patient, since oropharynx is the part with the highest frequency for fishbone impaction. Soft tissue radiographs are also important initially to localize the foreign body. However, it has to be considered that most of the foreign bodies are radiolucent. As a consequence, imaging should also include computed tomography (CT) and not only soft tissue radiographs. CT findings of fishbone impaction include intestinal wall thickening, localized pneumoperitoneum, regional fat stranding or a sign of obstruction. Nevertheless, a confident diagnosis can be established when the fishbone itself is identified as a linear calcified lesion. After proper imaging diagnosis, the ingested fishbone can be removed with endoscopic intervention [1, 3].