Vokoun, 37, was hospitalized during a Saturday practice after swelling was noticed on his thigh. It was diagnosed as a blood clot in his pelvis, and was treated with surgery at a local hospital, the team said.
"The most important thing right now is Tomas' health and well-being," Penguins General Manager Ray Shero said. "The clot was dissolved by the procedure, and the doctors tell us that he will remain in the hospital for several days. We will continue to monitor his progress after that."
The Czech Republic native compiled a 13-4-0 record with a 2.45 goals- against average and three shutouts last season for the Penguins.
It marked the second time Vokoun has been troubled with blood clots -- while a starter with Nashville in 2005-6, he missed the end of the regular season and the entire post-season due to clots in his abdomen.
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