Accidental ingestion of fish bones is a common ER presentation especially across Asia and the Mediterranean where the ingestion of unfilleted fish occurs regularly [3, 4]. Fish bones when impacted in the esophagus are a medical emergency. In close to 80% of the cases, the fish bone gets expelled from the GIT, but about 10–20% will require an intervention such as an endoscopic removal, and nearly 4% of these cases can present with an esophageal perforation. An esophageal perforation can be further complicated by mediastinal infection, vascular injuries such as pseudoaneurysm or aorto-esophageal fistula, tracheo-esophageal fistula, pneumomediastinum, pneumothorax, pericarditis, and other conditions. In rare cases, a fish bone can also migrate to adjacent structures such as the thyroid and cause complications [5]. Vessels that have been documented in fish bone induced injuries are the aorta, subclavian artery, internal carotid artery, and the internal jugular vein. A fish bone can either injure the vessel wall either by secondary or direct puncture or from an adjacent inflammatory reaction leading to vascular rupture contained by adjacent soft tissue structures and inflammatory exudate (pseudoaneurysm). In most cases, the site of esophageal perforation is sealed off by a hematoma or a blood clot, leading to partial tamponade and prevention of further bleeding [5]. In adults, the most common site of fish bone impaction is the oropharynx/hypopharynx, followed by the oral cavity and the esophagus. Within the oropharynx, the most common sites include the tonsils, followed by the base of the tongue, vallecula, and the pyriform sinus. In the esophagus, a fish bone commonly gets impacted at the 3 sites of physiological narrowing, namely, the cricopharyngeal muscle at the level of C5/C6, at the level of the aortic arch and left mainstem bronchus, and the gastroesophageal junction near the diaphragm. Esophageal fish foreign bodies are usually seen in adults > 40 years of age and mostly attributed to weakening of the swallowing mechanism [1, 6].
Fish bones are often difficult to identify on a plain radiograph, with the majority appearing radiolucent. The reported sensitivity of a plain radiograph in identifying a fish bone is as low as 32%, with a false negative rate of 47% [6]. Therefore, a negative soft tissue radiograph does not exclude a fish bone foreign body [1, 6]. Multidetector computed tomography (MDCT) is the preferred imaging modality for evaluating patients with accidentally ingested foreign bodies, with a reported sensitivity and specificity of 90–100% and 93.7–100%, respectively [7]. Potential mimickers of foreign bodies in the neck on MDCT include tonsilloliths, hyoid bone, cricoid calcifications, and motion artifacts. Additional pitfalls include artifacts from radiodense materials, e.g., barium or silver nitrate or even fecal material in the bowel [1, 7] and slice thickness [8]. Some experts believe the use of contrast [oral/intravenous (i.v)] can hamper the identification of fish bones on MDCT. Oral contrast can conceal fish bones in the intestinal lumen, while extraluminal fish bones can mimic blood vessels on i.v contrast studies [8]. If there is a strong clinical suspicion for accidental fish bone ingestion and if the initial study is an i.v contrast examination that was negative, then the study needs to be reperformed without contrast. Factors that can improve their detection on MDCT include the use of thinner reconstructions (3 mm/1.5 mm) as well as using multiplanar reformatted images for evaluation [8]. We recommend i.v contrast MDCT studies in all patients with suspected foreign body ingestion who have underlying lung disease as in our case, to rule out unsuspected complications.
As per the American Society of Gastrointestinal Endoscopy, an impacted fish bone is considered an emergency that requires immediate removal [9]. If the fish bone is directly visible, it can be removed by forceps. However, a fibreoptic/rigid endoscopic retrieval will be required in those cases where the fish bone is located beyond the level of direct visualization [10]. Surgical intervention is generally reserved for those cases with perforation or for complications that cannot be resolved endoscopically or following several unsuccessful endoscopic retrieval attempts [10].