IntroductionIn the United States, coins currently represent the most commonly retained esophageal foreign body in children [1–3]. Suspicion for a coin ingestion is typically brought on by witnessed ingestion and/or symp- toms such as gagging, choking, vomiting and dysphagia [1]. The di- agnosis is readily confirmed by means of two-view chest x-ray [4]. The lateral view accomplishes at least two goals: to confirm that the foreign body is posterior to the airway and also to identify multiple stacked coins or exclude a step off that raises concern for a button battery [5]. Button battery ingestion, which represents an emergency, can also be identified on anterior views by the so-called double halo or ring sign.Inherent esophageal narrowings at the cricopharyngeus muscle, right pulmonary artery crossing and diaphragm hiatus represent the common locations of esophageal impaction due to the relatively largersize of the coin at these sites. The current treatment is close observation for spontaneous passage versus endoscopic removal under direct vi- sualization and subsequent inspection to rule out esophageal injury [6]. This is performed in a non-emergent fashion when signs and symptoms of airway obstruction or esophageal perforation are lacking.In the present study we were interested in determining the accuracy of predicting the type of ingested coin by comparing coin measurements on pre-operative chest x-rays to known coin sizes published by the US Mint [7]. On a broader level, comparing radiographic measurements of coins to their known and highly regulated size provides insight into the accuracy of other measurements taken from x-ray such as tumor sizes or distance of foreign bodies to an