no ha person should do medical testing for 'peace of mind'. it doesn't work. all a HA person does is either doubt the medical test---find some sort of flaw in the test or the doctor got it wrong--- OR the ha person simply moves onto a new disease fear not covered by the test. THAT is the nature of this thinking disorder. It is part of the endless reassurance cycle.
As Flguy was fond of saying AND he was spot on as always - LASTING solace will not be found in an MRI tube, will not be found under a CT scan machine, will not be found by a sonogram, will not be found with another EKG, will not be found by giving another vial of blood, etc.
Any time we try to address our anxious over thinking through reassurance, IMO, it is doomed to fail.
so whether you have the colonoscopy or not is up to you, but don't expect that you will have solved HA long term or maybe even short term.