What happened when our son swallowed a 2p coin
The equivalent size of a US coin would be a Quarter, which has a diameter of 24.26mm
After my 5 and a 1/2 year old son swallowed a 2p coin, I assumed that it would probably come out of its own accord eventually, but we took him to the hospital anyway to get him checked out.
The initial thing to realize is that if you're child isn't gagging and hasn't been sick, the coin has traveled down the narrowest part of the child's body, which is the throat area. Beyond that, the next narrow aperture connects the stomach to the intestine, and this internal sphincter should in theory be able to process any object that has passed down the gullet. In theory.
In our child's case, the coin remained in the stomach, just above aperture to the intestine for well over a week, according to a couple of x-rays.
Because these are to be kept to a minimum, there is a careful balance to be struck between knowing what's going on with the coin, and not knowing. This can be a difficult call, and in our case, was a major reason why they decided to remove it. That is, rather than keep re-x-raying to see the situation, it was easier to just remove it.
Different professionals were around, and all seemed to have different opinions as to the importance of operating to remove the coin, which was a little confusing. Some tended to say there was no problem and it would easily pass through, or that it was at least worthwhile waiting, while others seemed convinced from the onset that it had to be removed. The final decision came from the consultant (a mystical figure who was always 'in theater', and which needed hours of waiting on our part to get his decision).
There didn't seem to be any concern about copper poisoning from the professionals in attendance.
General Anesthetic and Operation
The easiest way for them to remove the coin was to operate through the mouth. This might sound dramatic, but in fact it is a very common procedure. An endoscope is used which is a camera on the end of a wire, and we were told that a balloon device was inflated around the coin to get a grip on it, before pulling it out. Apparently it is a very routine operation.
A general anesthetic was administered, which in some ways was the most disturbing part of the operation. It just wasn't nice to see our child 'go under', as it were. Recovery, however, seemed to be pretty quick, and he was only unconscious for about half an hour. There were a few red marks around his mouth, where the tubes etc had been pressing down, but these cleared quickly enough.
A general anesthetic takes a while to recover from, however, and for a child to really shake it off. Our boy seemed not quite himself for a couple of days later.
If your child has swallowed a coin
If the coin is small, there's probably little to worry about, though checking to see whether it has come out or not, is worthwhile. However, according to the doctor very few parents are any good at checking their child's crap thoroughly - this is for obvious reasons I think! All I can suggest is... it could be time to get out that old potty again and a knife. Yup, a knife.
If the child has swallowed the coin without gagging, then in fact the most dangerous part of it has already occurred.
Obviously the age and size of the child has to be taken into account, as bigger guts can accommodate bigger objects. I read somewhere that it took someone's child 3 weeks to pass a 2p coin, but it was an older boy (about 9).
I echo something I read on a parenting forum, that it is really quite stressful not knowing how the coin is progressing and not knowing what to do about it.
Getting your child checked out - especially after swallowing a larger object like a 2p coin! - is the correct course of action and not silly. Hospitals are used to this kind of thing.