Best Diagnostic Imaging for ano-rectal narrowing

I am almost a year post-op rectocele repair...which also included a laparoscopy to remove alot of adhesions....my sigmoid colon was fused to the abdominal sidewall.  Prior to the surgery having a decent bowel movement was a big problem.  After the surgery my bowel movements were back to normal, no restrictions for a few months,  But, the restrictive b.m.'s have gotten progressively worse again through the months.  For a couple of months I have been doing anal dilation (given to me by my doc)...it helps to a point, as the dilator only goes up as far as the junction of the sigmoid colonl  So I do believe that that adhesions have again formed and my sigmoid colon is attached back to the sidewall.    Now, its like trying to squeeze a banana through a straw.  And I do take Metamucil twice a day.  So my Urogynecology doc wants to repeat a lap to take down the adhesions, but this time using a barrier to prevent more adhesions from forming.  But he wants to make sure there is nothing else causing the restriction of stool thru the anorectal canal.   So, my question to all of you who have had different kinds of imaging for your GI problems....  what would be the best imaging to one) rule out any other pathology, and two) confirm that there are adhesions formed around the sigmoid colon???  I would appreciate any answers you have.  Oh, and by the way, the rectocele repair was successful.  Thanks.