What to know about Jalen Hurts' blood clot diagnosis

Philadelphia Eagles quarterback Jalen Hurts, a Super Bowl champion and one of the NFL's top stars, is now facing a long absence because of blood clots in his lungs — and his team is facing serious questions over his medical treatment.

Hurts' agent, Nicole Lynn, and the Eagles said in a statement Monday his "prognosis is very good, and we anticipate a full recovery."

The condition can be life-threatening, and the Eagles say Hurts could miss the rest of the season. 

However, Hurts was cleared to play a week ago in London after a blood clot was found in his leg. He threw for 222 yards and a touchdown, but the Eagles lost to the Jacksonville Jaguars, 19-17. 

Just one day earlier, he was diagnosed with a superficial blood clot in his left calf and ordered by doctors to stay awake overnight, according to NFL insiders, who report the quarterback did not sleep for roughly 36 hours. After being released from the hospital, he was reportedly given some time to rest before taking the field against the Jaguars.

Since then, the diagnosis has worsened. The star quarterback is now facing deep vein thrombosis and bilateral pulmonary emboli with blood clots in his left leg and both lungs, the team and his agent said.

Deep vein thrombosis, also known as DVT, refers to a condition when a blood clot develops in the deep veins, usually in the lower extremities, according to the U.S. Centers for Disease Control and Prevention. A pulmonary embolism, or PE, is the term for when the clot breaks off and travels to the lungs, which can be life-threatening, the CDC says.

"You have a clot in your leg. The problem is it can travel up the veins and go to your heart, and from there, go to your lungs, and block the blood vessels in your lungs. And you get things called pulmonary emboli. That's very serious," CBS News chief medical correspondent Dr. Jon LaPook, who is not treating Hurts, told "CBS Mornings."

Whether it could be career-ending, LaPook said, it's "too soon to know."

"Normally what you do is you would treat this with blood thinners for three months and then sort of see what happens," he continued. "Now, they're going to follow him closely. It may be more than that, and then after that, you take them off the blood thinners."

LaPook said Hurts' doctors would then likely test his blood to see if there is an issue that increases the risk of clotting.

The revelation of the diagnosis is sparking backlash against the Eagles and its medical staff.

Eagles head coach Nick Sirianni did not answer Monday why the quarterback was allowed to play in London or fly back with the team to the U.S. after the game.

"I'm not a medical expert. I lean on our guys in all those situations, right? I'm a football coach," he said. "I lean on our medical experts in every situation. I have full trust and full faith in them."

Flying could be a concern, doctor says

A main question from fans is whether flying to London, or flying back, could have exacerbated the injury. LaPook said it's possible it could be an issue.

"In flying, you can get dehydrated, you're not moving around a lot," so your blood doesn't return to your heart as well, LaPook said. "When he got there (to London), they did a test, and they found this superficial thrombophlebitis, so a little clot, and they ... clear him to play. He ended up playing, and then right after the game, he flew back."

The fact Hurts did not sleep much was not as big a concern as the flying, LaPook said.

"Well, the bigger point to me is not the not sleeping, it's the fact that he had a flight there, a flight back within a few days," he said. "That increases the risk of blood clot in the first place. We tell people when they're on flights to walk around, maybe wear compression stockings."

The CDC makes similar warnings about flying.

"Extended periods of limited mobility are inherent to long-distance travel and can increase a traveler's risk for VTE," according to the agency. "An association between VTE and air travel was first reported in the early 1950s; since then, long-distance air travel has become more common, leading to increased concerns about travel-associated VTE."

Different organizations offer different guidance on how soon someone with DVT should fly, but they are significantly longer than the time it took for Hurts to fly back to the U.S.

The International Air Transport Association says if a person is stable, they should wait at least five days before a flight, while the British Thoracic Society advises someone with DVT or PE should wait two weeks before flying.

"Over the last few days, Jalen Hurts has received comprehensive medical evaluations by physician experts," the Eagles and Hurts' agent said in the statement announcing his long-term absence.

For now, the Eagles will wait three months to see how the condition is improving with blood thinners.

"We anticipate that he will have the opportunity to resume contact football activities when off the blood thinners," the statement said. "In the meantime, he will remain active around the team and continue to condition. More importantly, we anticipate that he will have no long-term effects. 

"We are thinking of Jalen and looking forward to a strong recovery."