If you get hurt on your job in Oregon, you have a few choices to make to start with. If you're injured but have time before you need to seek medical help, then you'll normally inform your employer of your injury and fill out the necessary paperwork before you head to the hospital or medical practitioner. For instance, if you fracture your wrist, you may not be in severe pain but need medical attention. It would be reasonable that in some cases, you could report your injury before heading to the doctor.
If you have to go to the hospital immediately following the injury or can't speak with your employer, then it's your doctor's responsibility to file your workers' compensation claim through the appropriate medical paperwork. Doctors and medical clinics are obligated to report your injury within three days of it taking place, and they will alert your employer's workers' compensation insurer.
In any case when you get hurt on the job, your employer has no right to prevent you from filing a claim. Your claim may not be approved by the insurer, but you still have the right to file it. If your claim is accepted by the insurer, then you'll start to receive your approved coverage and receive a notice that your claim has been accepted. If it's denied, then you'll be told about how you can appeal.
Sometimes, an appeal will result in your claim being accepted. That's why you'll want to make sure you have good evidence of your injury and what happened at work to cause it.
Source: Oregon.gov, "I got hurt on my job, what do I do?," accessed Sep. 02, 2015