Fm 49, all docs say trans-vaginal us can not cause prolapse to pelvic organs. what if procedure done roughly on narrow introitus with weak structure?

No : Ultrasound uses sound waves. There is no possible scientific connection between and ultrasound and prolapse. You state all doctors have already told you this . Maybe it's time to believe them.

Highly improbable: Cannot imagine a set of circumstances in which, during a normal examination with trans-vaginal ultrasound one could produce the damages necessary to induce the changes you describe.

No: There is no current research that has suggested the use of ultrasound will disrupt pelvic floor support.