What are some reasons that a straight catheter doesn't go in or stay in the bladder?

When I was in the hospital, after my leg operation, I could not urinate (not sure if it was b/c of a leg nerve block or dilaudid).
I had a completely full bladder where it was fully distended.
They attempted a straight cath but it kept slipping out. They called several different nurses and even a doctor. The 5th or 6th time they tried, I had a seizure (I have a seizure disorder so it could have been from the meds or too much stress on the body). It was a horrible seizure where they had to call Rapid Response Team level 2 because of tachycardia and long time in the post-ictal state.
MY question is i wanted to know why the cath kept slipping out.
I can't find the answer online and would appreciate if a nurse, doctor, or anyone could help me with the answer. :)
Also, if anyone has any other input on connections involved with the seizures, caths, dialudid, leg nerve block and surgery?

-I am a 27 year old female if that has any importance to the situation.
THANK YOU!

a straight cath is meant to go straight in empty and go right back out. an indwelling cath has the 10 cc balloon on the end and that one is meant to stay. there is many reason why it might have been difficult to get in a woman can be difficult to cath at time ex specially if you had some swelling or other things going on.

If a catheter isn't held in place it is going to fall out. Now if it had a balloon on the end of it that was filled then it could have been because of the pressure. I cath and if I don't hold it in place it will come out. That is just how it is.

A straight cath and a foley catheter are two different things. A straight cath is designed to go in the bladder, release the urine and come out. It is not designed as a indwelling device. A foley cath has a 10cc balloon on the end that is inflated once the foley is in the bladder, verified by urine, this balloon keeps the foley in place by not allowing it to slip out of the bladder.