Why? If you read the fine print in your policy, you'll probably see that--in some circumstances--they can refuse to cover you if you don't call them before you head to the emergency department or within several hours of arriving. Considering that an ambulance ride can cost just slightly less than a space shuttle mission, it's a good tidbit to remember.
And really, what's the trouble with phoning them? Once you get a finger on your bleeding artery, just use your other hand to dial the phone. To make it easier, why not put the 24-hour claims hotline on speed dial, right below your favorite pizza joint?
In being practical, having your insurance ID number handy will smoothen your experience at the ER anyway, and you can be sure that your insurance card will magically vanish from your wallet or purse because it's the first time you've really needed it in the last 15 years. So the phone call could prevent a common hold-up. And your relative or friend can do it for you (your health care advocate, if available, would naturally be the best choice).
Find out more about this book:YOU: The Smart Patient: An Insider's Handbook for Getting the Best Treatment