From the National Capital Poison Center:
1. Call the 24-hour National Button Battery Ingestion Hotline at 202-625-3333 immediately.
2. If avilable, provide the battery identification number from the package or from a matching battery. [Hearing aid batteries are zinc-air and come in these sizes: 5, 10, 312, 13, and 675].
3. An X-ray must be obtained immediately to be sure that the battery has gone through the esophogus into the stomach. Do not wait for symptoms to develop before getting an X-ray. If the battery remains in the esophogus, it must be removed immediately. Batteries lodged in the esophogus can cause burns in just 2 hours. Battery removal is done with an endoscope; surgery is rarely indicated. DO NOT give ipecac.
4. If a battery have moved beyond the esophogus, it can be expected to pass by itself. Passage may take several days, or even months. Removal is NOT indicated if the battery has passed beyond the esophogus and the patient is asymptomatic. Once you are sure the battery is not in the esophogus, the patient can be sent home to wait for the battery to pass. Watch for fever, abdominal pain, vomiting or blood in the stools.
5. Send passed battery to: National Capital Poison Center, 3201 New Mexico Ave, Suite 310, Washington DC 20016.