Therefore, you can do another one. On my first defecography 7 months ago, all they found was pelvic floor descent. My second defecography showed a small rectocele of 1.9 cm and grade 1 sigmoidocele, so something's going on back there.
It's quite possible they missed this the first time. Ask your colorectal surgeon for another defecography. Tell him your bowel issues still persist.