This was posted online in October by a supposed medical death investigator...
"It depends, on the method you use, where you die, and how long it is until you are found.
You can only donate the 'main organs' if you are in a hospital and being kept alive with machines. You must either be pronounced brain dead, or your family must decide to withdraw care if they decided your recovery would not be compatible with a quality of life.
The heart, lungs, kidneys, pancreas, liver, etc. must be kept 'perfused' with oxygenated blood. This can only happen in a hospital. Then the OPO (Organ Procurement Organization) needs to have time to make matches of recipients and get them prepared for the transplant. This usually takes 1–2 days.
So to donate those organs you will have had to injure yourself in a way that would not destroy those organs, and be found, and able to be kept alive long enough to reach a hospital and be stabilized, yet not so long that you begin to get septic or have your organs go into failure.
If that did not occur tissue donation can still save and improve several lives. Donation of tissues such as corneas, skin, bones, heart valves, tendons, muscle, veins etc. To donate those you need to be found and refrigerated within a certain amount of time after you were last known alive. (Different OPO's have different standards, but usually within 12 hours.) This is much more common. But the method you use can also determine which tissues can be used.
Every suicide (in the USA) falls under the jurisdiction of the Medical Examiner/Coroner. If you get an autopsy, this may also affect what can be recovered.
If you are found in water, the type will vary by the amount of time you were submerged. For example we can recover on someone several hours if found in bath water, but if you were found in a stream, lake, or ocean it must be from 10 minutes up to an hour. Brackish water usually must be under 10 minutes.
If you hanged yourself, often your eyes will be restricted until after your examination by the ME/Coroner, which may time the OPO out.
If you used needles to inject yourself, none of your tissue will be able to be used. This is due to the high incidence of HIV and Hepatitis from IV drug abuse. Even if this was your first time using a needle.
Gunshot wounds can damage many tissues as the projectile tumbles around.
If you exsanguinated (lost all your blood), we will not be able to transplant tissue. We need to test the blood for many diseases for the health of the recipients. Slitting wrists is not a popular, or effective, method, but there are many more injuries where this could happen.
Burns, either thermal chemical, are usually not accepted, but depends on extent.
My off the cuff estimation would place suicides as a source for 1/2 to 1/3 of all of our donors.
This does not mean I think you should take into considerations that you feel like your death would be helpful to others. Or that your death could contribute to society in this way. We are willing to wait. You can still donate after you live a long and productive life."