Cat swallowed string -- please help

Hi: Last night my 8-year-old male cat Simon was playing with a cat toy with a 20-inch string. He plays with it often, so I didn't notice anything wrong until later that night when I realized that there was only four inches of string left. I have hunted high and low and the string is nowhere to be found. So I am 90 percent certain that he ate it. I talked to the vet, who said that a string of that length is highly unlikely to pass through naturally. He is going to do an x-ray shortly to see if the string is in his bowels, but the problem is that the string itself may not show up on the xray -- they'd only be able to tell if the bowls are scrunched together. The vet says he would recommend exploratory surgery through the stomach to see if the string is in there, but said it may not be, and they may still have to go into the intenstines in a few days if he has symptoms. I don't know what to do, especially since the cat has no symptoms and I'm not even positive that he ate the string. But the vet said there's huge risk in waiting until he does have symptoms becuase by then it means it's damaged the intestines and the surgery is much, much riskier. So what do I do? What would you do? Put him through exploratory surgery? Or wait? Please help, I love this cat more than I can express and want to do the right thing for him. Thanks.

Oh, gosh, I'm so sorry - here's a link to one site about pets eating strings, etc., and the reason it's considered a huge risk. http://www.web-dvm.net/giforeignbody.html

I hope things work out - actually, I hope you find the darn string or he poops it out, but I think the vet is right - something that long might not pass ok.