PITTSBURGH -- Pain is one way the body's tells us something is wrong. But what kind of pain should send up right to the emergency room and what pains can wait.

Janet Duff, of Reserve Township, is a healthy woman and wasn't worried when she started feeling pain when she took deep breaths.

She thought she could shake it off, but when it didn't go away she went to see Dr. Christine Mackey at Allegheny General Hospital.

Mackey said, "Her exam was normal, vital signs normal and we ended up getting a blood test."

The results of the blood test were alarming. The day after her blood test she got a call at work from Dr. Mackey.

Duff said, "I picked up the phone at work and she said get to the hospital immediately."

It turned out Duff had a blood clot in her lung.

Janet had no leg pain, but most blood clots begin in the calf and can break off and travel to the lung, which can be deadly.

If you have pain and swelling in the calf see a doctor immediately.

And there are other pains that should send up red flags.

Mackey said, "The absolute worst headache of your life. That's a medical emergency. It can represent, in the worst case, bleeding in the brain."

Don't ignore pain or discomfort in the chest, throat, jaw, shoulder, or arm.

It could signal a heart attack.

Heart attacks do not always cause chest - crushing pain, especially in women.

Mackey said, "Middle-aged women do not come in with that elephant sitting on their chest feeling that men present with. It may just be jaw pain."

Severe abdominal pain could be caused by anything from your appendix to an intestinal blockage.

Mackey said, "If it's severe pain, doubling you over and unable to function, you need immediate medical attention."

Other pains that shouldn't be ignored:

Pain in the lower back or between the shoulder blades can signal anything from arthritis to a more serious aortic dissection.

Burning, numbness or tingling in the feet or legs could be a sign of diabetes.

And vague, combined, unexplained pain can be a sign of depression.