Good Morning, please try not to over worry re your procedure. The procedure you are having is called a cerclage. The Dr will put in a running stitch around your cervix and then pull the suture closed just like the draw strings on a pair of sweat pants. Usually a short acting pudendal block is used - a spinal anesthetic.
They will numb your skin a bit so you don't feel the anesthetic when it is administered . Usually the anesthetic will wear off quickly after the procedure and you are allowed to go home. They will keep you and monitor your baby for a length of time to the best of my knowledge but if all is ok and you are feeling well - home will feel good to you.
This procedure should help keep your cervix closed and protect your baby from being born to early.
Please ask questions of your Dr. before you sign any permits so you understand the procedure. Remember even people without anxiety would be worrying re any procedure that is new and unknown to them. You are normal and know we are all here for you.