Syringe top may have gone down throat

Question
I was administering liquid medication to my 5 month old cat today and when I walked back to rinse the syringe I notice the little yellow top was missing.  I searched the area I was in for it but it is no where to be found.  I am wondering if it may have slide down his throat while I was giving him the meds.  I do go slightly to the side when giving him the meds but I am unsure as to if this might be possible.  He didn't choke or anything like that but I really can't find the top.
If he did ingest this piece of plastic material what should I do?  Should I take him to the vet right away?  Can they find it?  

Answer
Hey !

Hmmmmm, I advise you to call your vet A.S.A.P if you suspect that the syringe top was injested, it is urgent that you contact your local vet A.S.A.P. Look around the house a little more to make sure that the cat did indeed injest the yellow top. Also look out for these signs in your cat : Drooling, frequent vomiting, projectile vomiting, anorexia, diarrhea, depression and dehydration.

If you don't mind I would like a follow up of this email to let me know how things go. I hope all goes well.