The ER physician ordered an ultrasound of the man's legs that revealed a DVT in the right leg. But that didn't explain why both of his legs were swollen and weak.

Next, the physician ordered a CT scan to get a better look. But the radiologist pointed out that the intravenous contrast dye needed for the scan could harm the patient's already compromised kidney function.

The ER physician explained the pros and cons to the patient, who agreed to have the test despite the risk.

The CT revealed what the ultrasound did not: blood clots, or thrombi, not only in the right-leg veins, but also in the pelvic veins above both legs, in the inferior vena cava, and, most concerning, beyond the filter that had been installed years before.

Additional lab work revealed that the patient had thrombophilia, a condition in which the blood clots too easily.

The patient was given the blood thinner heparin, and a vascular surgeon was consulted.

Of the available options, the medical team and the patient agreed the wisest was thrombolysis, the catheter-directed removal of the clots with potent clot-dissolving medication called tissue plasminogen activator (t-PA). After 24 hours of thrombolysis with t-PA, the patient's kidney function was normal, and after 48 hours, nearly all of the thrombi were dissolved. The catheters were removed, and the patient's symptoms disappeared, though he will have to take the oral blood thinner warfarin indefinitely.

Vena cava filters can be lifesaving. But if they are left in place, they can create complications like this patient suffered. That's why the FDA recommends removal of these filters as soon as protection from a blood clot is no longer needed.

After he had time to recover from his ordeal, the patient had to return to the hospital to have his retrievable filter removed.