What Causes Rectal Pressure After Undergoing Cystocele Repair?

I am a 37 YO G10P8. I just had an A/P repair done yesterday for the correction of stage 3 cystocele and rectoceles. I feel constant pressure in the rectum now, like I need to have a BM. I have gone to sit on the toilet several times and nothing comes out, except flatulence, and I'm afraid to push too hard. I have taken my stool softener as directed. How long is this feeling of rectal pressure going to last? Should I be concerned about jeapordizing my repair by pushing too hard? Oh yeah, and what is the average blood loss associated with anterior and posterior colporrhaphy?