When is a blood clot an emergency?

My friend had a blood clot in her leg after surgery. She called me and asked if she should go to the emergency room. Symptoms were: shortness of breath, hard time breathing, dizziness, chest pain and coughing up blood. I called an ambulance for her because I thought she would faint. The emergency room doctor said it was the best thing to get her to a hospital right away. Also, a blood clot can spread. It is serious and you can die. I am so glad we got her to the hospital. It may have saved her life. Blood clots are serious.