"Yes, Parkinson's disease can cause rectal prolapse as a symptom of neurogenic bowel dysfunction (NBD):
Symptoms of NBD
Bowel
Constipation, fecal incontinence, rectal bleeding and prolapse
Other
Urinary tract infections (UTIs), abdominal pain, anal fissures, autonomic dysreflexia
Other conditions that can cause NBD include multiple sclerosis, spinal cord injury, and stroke.
NBD is caused by conditions that impact the nervous system, which plays a role in the proper functioning of the pelvic floor. People with Parkinson's are more likely to experience bladder and bowel problems than people of a similar age without the condition.
If you have a change in bowel habit, particularly if you see blood in your bowel motions, you should report it to your doctor."

I am in Stage 4 of PD. My Constipation is very severe and I've tried all sorts of treatments like Prunes, Fiber, Metamucil, Collace, etc. to no avail. As an added complication, I also have Hemeroids, which periodically bleed on me. I don't know if, because of that I have NBD.

Very hard to stay positive with this problem. General surgeon offers no help, but we are looking at specialist. Expect same “ no can do” but bracing for another no. Then, there are no answers.
Good luck, Lynne