No one wants to take a trip to the ER, but there are times when it's necessary. Before you go, keep in mind hospital emergency centers are designed to treat medical emergencies not routine illnesses. About half of all ER visits are unnecessary. Please do not substitute an emergency department for a family doctor, and of course, never hesitate to call 9-1-1 if you believe your situation is a medical emergency. Today, Dr. Drew Williams, Medical Director at the Emergency & Trauma Center at The Medical Center has tips to help you determine if your condition calls for a trip to the ER.