Louise, age 38, was scheduled to have a hysterectomy. Her doctor had decided to perform the surgery to eliminate the very heavy bleeding that she had had for years with her periods. She said, "The attitude from the doctors and nurses was, 'This is routine surgery, a walk in the park.'"

The operation proceeded uneventfully, and Louise soon returned home. She does not recall much, if any, discussion about possible complications or symptoms to watch out for.

She said, "One week later, I got up in the morning and had an awful pain in my shoulder when breathing. It was hard to catch my breath. I went back to the surgeon. He said, 'What's wrong with you is a shoulder problem. Go see an orthopedic surgeon.'"

Louise continued, "As the day went on, it got harder and harder to breathe. My friends took me to the hospital. A blood clot had gone through my heart to my lungs."

Dr. John A. Heit of the Mayo Clinic in Minnesota notes that more than 900,000 people develop blood clots each year. Many people believe that blood clots are usually a result of long airplane flights. However, Dr. Heit reports that more than two-thirds "are related to recent hospitalization."

Further, nearly a third of the people who get blood clots die as a result. This situation typically occurs when a blood clot breaks off and travels to the lungs, where it interferes with breathing.

As was true in Louise's case, blood clots may not become evident until the patient is home. At that point, people may have let down their guard. They may have assumed that any risk related to being in the hospital went away when they drove out of the hospital parking lot.

Dr. Heit reports that blood clots are more common than heart attacks or strokes, and cause more deaths than either of those. He also points out that deaths from blood clots are expected to increase because older people are at greater risk, and the population is aging.

Dr. Joseph A. Caprini at Northwestern University has developed a model to assess a patient's risk of developing a blood clot. It lists about two dozen risk factors and assigns points to each. Three of the risk factors are being age 40-plus, having surgery that lasts 45 minutes or more, and having recently fractured certain bones.

As an example, imagine a 55-year-old woman in the hospital after having surgery lasting 60 minutes to treat a broken hip. She would score 1 point for her age, 5 points for her recent broken hip, and 2 points for the 60-minute surgery, for a total of 8 points. Of the people who score 5 or more points, 40-80 percent develop blood clots.

Additional examples of risk factors for blood clots among hospital patients are obesity and smoking. In fact, most people who land in the hospital are at risk, so it's worth paying attention to this potential complication to safeguard your life.

Louise received emergency treatment and recovered from her blood clot. Looking back, she was disturbed that the surgeon assumed right away that her new problem had nothing to do with the operation she'd just had. This dangerous assumption could have killed her.

Five action steps can help you avoid this deadly problem:

  1. If you know that you are going to be hospitalized, start to evaluate your risk for blood clots by completing the easy quiz at preventdvt.org. It is called "DVT Risk Assessor Tool." (DVT stands for deep vein thrombosis, the technical term for a blood clot.)    
  2. Print out the results and talk with your doctor about them. Factors unique to you may mean that you have more risk or less risk than the quiz suggests.    
  3. If you are at risk, ask for a plan to prevent blood clots.    
  4. Make sure that the plan is put into action.   
  5. Ask what symptoms to watch for and what to do if they arise. Generally, you will need immediate medical attention.

When you are aware of the often-overlooked risk that blood clots present, you can be on the alert to help prevent the needless tragedies they often create.