Pulmonary embolism (PE) or blood clot to the lungs occurs in half a million patients every year. Death is often the first sign of this problem. That's why it's called a "silent disease."

Doctors are aware this problem can occur most often during or after an operation of any kind. That's why research is ongoing to find out who's at risk and what can be done to prevent blood clots. The risk of a blood clot is greatest with surgery to the pelvis and legs. This is especially true for total hip and total knee replacements.

The risk of blood clot with spinal surgery hasn't been fully reported. Only case reports or studies after the fact are available. Recently a group of Italian doctors from several centers started a study to follow this problem. The results of their findings may help formulate future decisions about prevention of blood clots after spine surgery.