Derek managed to save four people who were involved in the crash, and was walking back to his vehicle when he was struck by a semi-truck. Derek was then rushed to the nearest ER, and if they had done a simple CT scan, he could have been saved. ... Derek was later pronounced brain-dead.

Who failed to save Derek Shepherd?

But, as it turns out, Meredith (Ellen Pompeo) was in for a shock when she opened her front door to welcome the couple into a house party and realized that her friend's new love interest, Penny (Samantha Sloyan), was the doctor who failed to save her late husband, Derek Shepherd (Patrick Dempsey).

Why didn't they give Derek head CT?

When his ambulance showed up, the on-call doctor didn't even want to take him. He kept saying they weren't a trauma center and weren't equipped to deal with the four car accident victims and Derek. ... They didn't take a head CT, so they didn't know he had a brain injury.