NEW YORK (3rd UPDATE) - US Secretary of State Hillary Clinton was hospitalized Sunday when doctors discovered a blood clot caused after she fainted and suffered concussion earlier this month, her top aide said.
The latest health scare for the globe-trotting Clinton will likely keep her out of the public eye a bit longer, just as she prepares to step down after four years as America's top diplomat.
Clinton, 65, fell ill with a stomach bug on her return from a trip to Europe earlier this month that caused the former first lady to become severely dehydrated and faint, suffering a concussion.
"In the course of a follow-up exam today, Secretary Clinton's doctors discovered a blood clot had formed, stemming from the concussion she sustained several weeks ago," her aide Philippe Reines said in a statement.
"She is being treated with anti-coagulants and is at New York Presbyterian Hospital so that they can monitor the medication over the next 48 hours," he said.
"Her doctors will continue to assess her condition, including other issues associated with her concussion. They will determine if any further action is required," he added.
Reines did not elaborate further on her condition, and would not specify where the clot had formed. And the streets outside the hospital in Clinton's home state were deserted late Sunday on a cold December night.
Previously in 1998, when she was first lady in the White House of her husband and then-president Bill Clinton, Clinton suffered a blood clot in her leg that she has described as "the most significant health scare I've ever had."
"That was scary because you have to treat it immediately -- you don't want to take the risk that it will break lose and travel to your brain, or your heart or your lungs," she told the New York Daily News in October 2007.
Clinton has been off work since her return from her last foreign trip on December 7, although her staff has said she has been working from home. Only a few days ago, Reines said she was expected back in Washington this week.
Her rare and lengthy absence from public life had sparked claims from some of her fiercer critics that she was trying to avoid testifying before lawmakers investigating a deadly attack on a US mission in Libya.
The American media has also been rife with speculation and rumors about her whereabouts and her condition, but it is not believed to be life-threatening.
Clinton's doctors said she had become severely dehydrated due to the effects of the stomach bug and fainted, suffering a concussion. They recommended she stay off work, and ordered her not to fly until at least mid-January.
Clinton has flown almost a million miles since taking office four years ago, visited 112 countries and spent some 400 days in a plane. She has been hugely popular as secretary of state, and has the highest ratings of any cabinet member.
Many believe she will try to run again for the White House in 2016, after she was narrowly defeated to the Democratic Party nomination by Barack Obama in 2008.
The secretary's health prevented her from testifying on December 20 to US lawmakers about the September 11 attack on the US consulate in the eastern Libyan city of Benghazi.
The assault, in which the US ambassador and three other American officials were killed, sparked a political firestorm in the United States.
Republican lawmakers and some media outlets opposed to the administration slammed Clinton's absence from the hearings, with her harshest critics suggesting she was faking illness.
Republican Senator Lindsey Graham said Sunday it was "absolutely essential that she'd testify. I want to know from the secretary of state's point of view, were you informed of the deteriorating security situation?"
Graham also told Fox News Sunday Republicans would not conduct the nomination hearings for Senator John Kerry, tapped to replace Clinton, until she has appeared before them.
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