Oesophageal coins invisible on chest radiography: a case report.

BACKGROUND: Coins are made of metal, which is generally radiopaque, and so physicians often have the misconception that all coins are detectable by radiography. Here, we report a case of intentionally swallowed coins in the oesophagus of an adult; the coins could not be detected on chest radiography but were detected using computed tomography (CT).

CASE PRESENTATION: A 46-year-old woman with a history of depression presented to the emergency department after an intentional medication overdose and ingestion of two Japanese 1-yen coins. She complained of persistent retrosternal discomfort. In order to confirm whether the coins were in the oesophagus or trachea, an anteroposterior chest radiograph was obtained; however, no coins were detected. Owing to her persistent symptoms, a chest CT was performed. On the initial CT scan, two 1-yen coins were observed in the oesophagus: one in the middle oesophagus and the other in the lower oesophagus. After the scanning, the patient drank water with permission, but vomited. No coins were found in her vomit, and the symptoms of retrosternal discomfort had completely disappeared. A subsequent CT scan revealed that the two 1-yen coins were in the patient's stomach.

CONCLUSIONS: Japanese 1-yen coins are made of 100% aluminium, which is less radiopaque than the metals that make up coins (nickel, bronze, and lead), and so, they were not visible via chest radiography in our case. Detecting very small or thin radiolucent foreign bodies is not possible using a chest radiograph or contrast oesophagram, but is possible via CT. CT is both increasingly convenient and non-invasive, unlike endoscopy or bronchoscopy, and so, the use of CT scans should be considered in cases of possible radiolucent foreign body ingestion.