I read your question carefully and I am sorry about the condition your beloved one was in. Judging from the dates I assume a long time has gone by and his condition might be changed for better or for worse, but I am answering anyway so that you can have perhaps some more clarity.
First you blame the stroke on coagulant drugs that the patient has supposedly been given, but unless you have any documentation on that I doubt that to be the case. Surgeons do not give coagulant drugs in their routine work, actually often times they actually give low dose anticoagulant
drugs because of the risk of deep vein thrombosis
in their patients due to immobility.
So the cause must be looked elsewhere. Unfortunately you say nothing on previous history which could reveal risk factors for stroke, data such as age, hypertension
, heart abnormal rhythm, high cholesterol
. You mention also nothing on the tests he had, stroke location, heart tests (as many thrombi form in the heart, or can travel from the veins and tranverse through a hole between the atria), tests to look for atheroclerotic plaques in major arteries supplying the brain. So it is hard to pinpoint the origin of the stroke, let alone point fingers for it not being prevented.
I can not comment why weren't the symptoms noticed, perhaps you might be right in that. Regarding what you call premature discharge though it seems to be 3 months after the stroke. That time is more than enough in my opinion, a stroke is an acute event, after the first few weeks have passed there is no specific treatment for it, only physical therapy
to help recovery.
Since he fell into a coma later I assume he had another stroke. Whether that could have been prevented depends on the origin for which the data I mentioned above would be necessary as well as info on the treatment he was taking, treatment lowers the risk for stroke recurrence though doesn't completely eliminate it.
I hope to have been of help. In case you still care to discuss the issue please bring some more info and I would be happy to review it and try to give a better answer.