I think my kitten ate a small metal ball

I noticed that the bell on my 7 week old kittens collar was broken & the ball on the inside was missing. I've been looking for it around the room she was in but can't find it. Will she be able to pass it? What should I be looking for before taking her to the vet? Any advice would be appreciated.

Hello - there is a world of space between 'missing' and 'eaten' and I'd wager that even if a non-starving kitten had noticed a small metal clapper dropping out of the bell on their collar, they would be unlikely to to eat it.  Such items are easily lost within houses and cats can be quite fastiduous eaters compared to dogs.  Assuming that this happened however, depending how small we are talking relative to the cat, it might slip right through the digestive system, or sink in the stomach and stay there (this could be a problem if not stainless but corrosive?) or pass out of the other end.   Sometimes, however, depending on the size and shape, very sharp splinters of metal could pass through the gut wall, causing damage and predisposing to peritonitis.  You should talk a plan of action through with your vet, but imaging a tiny slither of metal in a healthy cat with no evidence of eating, may be more difficult and frustrating than you think.  Depending on the details, your vet might make a strong argument for watching and waiting to see what happens.

A metal detector may be worth considering, of course - again depending on the size.  I do think that a large percentage of 'missing' items turn out not to be inside the patient after all.