cat with (cord?) hanging out of butt

Question
My cat (who acts like a goat) has a 1/8 inch string?/cord? hanging out of his butt today.  He has a tendency to chew on plastic bags and cardboard boxes.  The cord has been there since this morning.  I was hoping he would poo and it would come out.  But it is still there tonight.  I don't know if maybe he was able to poo today and somehow the poo just passed by the cord.  Or if maybe there is something at the end of the cord which might be preventing him from pooing.  How can I tell if he IS able to poo?...(there are four cats in the house).  How long can a cat go WITHOUT being able to poo before it is dangerous to his health? Should I just wait and see if he CAN pass it or does he need to go to a vet urgently?  His disposition seems normal...He's not acting like anything is wrong with him...

Answer
I am glad the string is no longer sticking out, but did you find it in the BM? that is critical as it may have been sucked back up in. Just continue to carefully monitor - if any vomiting, pain in belly, lethargy, not eating - go straight to the  clinic.  

This is one time when conventional medicine is needed. Strings can pass normally, but often they get stuck in the intestine, actually cutting the intestines.
Unless the string has completely passed and you saw it in the stool, you do need to go to the clinic, and probably will need an X-ray and maybe even a Barium study.