The magic coin

Cite this article as:
Yamamoto, L. The magic coin, Don't Forget the Bubbles, 2014. Available at:

This is a 20 month old female who presents to the emergency department after swallowing a coin, according to two older children who were playing with her at the time. They don’t know what type of coin it was.

Her mother has not noted any difficulty swallowing, drooling, or respiratory difficulty.

Exam Findings

T37.1 (tympanic), P100, R36, BP 100/65, oxygen saturation 99% in room air.

Alert, active, no distress, no drooling. Eyes clear, TM’s normal. Oral clear, moist mucosa. Neck supple. Heart regular without murmurs. Lungs clear. No stridor, no wheezing, no coughing, no tachypnea, no retractions.

Abdomen soft, flat, non-tender, bowel sounds active.

Color, perfusion good. Speech normal for age. Ambulating well.

An AP radiograph of her trunk is taken.



This radiograph shows a coin in her stomach. However, upon closer inspection, it has an unusual appearance. View close-up of coin.


The “coin” shows an internal ring just inside its perimeter. This internal ring indicates that this is a disc battery, not a coin. Since disk batteries (also called button batteries) have different GI consequences compared to coins, it is important to distinguish an ingested coin from a disc battery by history or radiographically.

Disc batteries will often have the characteristic internal ring appearance if taken in the AP direction. If taken in the lateral position (on edge), it may show a bulge on one side (bilaminar appearance). When viewed obliquely, it may be difficult to distinguish a coin from a disc battery since none of these signs may be radiographically evident.


This lineup shows a radiograph of a series of 6 disc batteries and a dime. The first disc battery on the left has the positive terminal facing toward us. The second battery from the left has its negative terminal facing toward us. On this second battery, the black plastic insulator is visible in the photograph. However, the radiograph of both the first and the second disc batteries show the internal ring sign of the plastic insulator. The black plastic insulator on the first battery is on the other side of the battery.

The radiograph will still show the internal ring of the plastic insulator regardless of which way the battery is facing (AP or PA). The fourth battery from the left also shows a plastic insulator, but the radiograph of this battery does not show the internal ring. It could be absent because the battery casing is thicker than the first and second batteries.

Thus, the absence of the internal ring radiographically does not rule out a disc battery since the appearance of the internal ring is highly dependent on the degree of X-ray penetration, the angle of the battery, and the thickness of the battery casing. The third and fifth batteries from the left are viewed from the side.

On its side view, the battery has a rectangular appearance with a bulge on one end. This bulge represents the negative terminal of the battery as shown in the corresponding photo below it. The radiographic shadow also identifies this bulge which can be described as frosting on the cake (bilaminar appearance). However, this radiographic sign may be absent if the battery is oriented obliquely, or if the battery is very thin.

The battery to the extreme right is oriented on edge. The side view of this battery does not easily show the bulge of the negative terminal because this battery is very thin as can be seen in the photograph. Disc batteries contain various chemicals depending on the type.

Standard dry cell batteries contain zinc-carbon, alkaline, and nickel-cadmium compounds, but these are generally not found in disc batteries. Disc batteries generally contain silver oxide, mercuric oxide, or lithium salts. They may also contain concentrated caustics of potassium or sodium hydroxide. Most disc batteries in use today are the silver oxide or lithium types. However, many inexpensive or disposable child toys may still contain the less expensive mercuric oxide disc batteries.

Disc batteries lodged in the esophagus can potentially cause serious problems in three ways:

1) Direct pressure necrosis (similar to coins or other inert foreign bodies).

2) Caustic injury due to the leakage of sodium or potassium hydroxide from a leaking battery.

3) The esophagus can also sustain injury from low voltage burns from a disc battery that still has a charge.

For these reasons, all disc batteries lodged in the esophagus should be removed expeditiously to avoid these injuries.

Disc batteries that leak can also cause toxicity from the absorption of metal compounds. Mercuric oxide batteries can potentially cause mercury poisoning resulting in gastritis, vomiting, and hypovolemic shock. This is not likely to occur for several reasons:

1) Most disc batteries do not leak. They negotiate the GI tract and are passed intact in the stool.

2) Most of the mercuric oxide from old batteries is converted to insoluble metallic mercury which is not absorbed.

3) Any mercuric oxide that happens to leak out of the battery is converted to elemental mercury in the presence of gastric acids.

Silver salts from silver oxide batteries may be corrosive, but they are minimally toxic. Lithium is a highly reactive metal under extreme conditions such as fire. Complications have not been reported in the literature following ingestion of a lithium disc battery.

Most disc batteries will pass through the GI tract without difficulty. A radiograph should be taken to localize the battery.

Esophageal batteries should be removed expeditiously. If the battery is beyond the esophagus, the patient may be sent home and instructed to watch for symptoms of toxicity and passage of the battery in the stool by straining all stools. Induction of emesis is generally not successful and it may be potentially harmful since the battery is potentially caustic.

A repeat radiograph is usually not indicated until 4 to 7 days after the ingestion if the battery has not been recovered. Cathartics may accelerate passage of the battery. If passage is delayed, the risk of leakage and the potential for complications depending on the contents of the battery must be assessed to determine the need for endoscopic or surgical removal.

Although most batteries will remain intact for two weeks or more, some batteries may have defective casings or they may be old and be leaking at the time the battery is swallowed.



Poisindex. Volume 83, Expires 2/28/95. Micromdex Inc. Kuhns DW, Dire DJ. Button battery ingestions. Ann Emerg Med 1989;18:293.

Maves MD, Lloyd TV, Carithers JS. Radiographic identification of ingested disk batteries. Pediatr Radiol 1986;16:154.

Sheikh A. Button battery ingestions in children. Pediatr Emerg Care 1993;9:224. Temple DM, McNeese MC. Hazards of battery ingestion. Pediatrics 1983;71:100.

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Prof Loren Yamamoto MD MPH MBA. Professor of pediatrics at the University of Hawaii and a practising pediatric emergency doctor in Honolulu. | Contact | View Loren's DFTB posts

Author: Loren Yamamoto Prof Loren Yamamoto MD MPH MBA. Professor of pediatrics at the University of Hawaii and a practising pediatric emergency doctor in Honolulu. | Contact | View Loren's DFTB posts

One Response to "The magic coin"

  1. John kielty
    John kielty 5 years ago .Reply

    This article was very clear as to the management of this issue

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