Prospects good for Hillary Clinton recovery: doctors Secretary of State Hillary Clinton is under observation at a New York City hospital after being treated for a blood clot that apparently stemmed from the concussion she suffered in a fall earlier this month. By Maggie Fox, NBC News Secretary of State Hillary Clinton is in New York City's Presbyterian Hospital for a fourth day after being diagnosed with a rare blood clot in her head. She is likely to completely recover, according to doctors. Clinton, who fainted and hit her head in December, probably developed the blood clot as a result of the injury, doctors say. It's in an unusual place - in a large vein that drains blood from the brain, and that sits on a covering of the brain called the dura, right beneath her skull. "This is in a weird space," NBC News medical editor Dr. Nancy Snyderman told TODAY on Wednesday. Clinton hasn't been seen since she made an appearance Dec. 7 in Belfast, Northern Ireland. Her spokesman said she had a stomach virus, became dehydrated and fainted, suffering a concussion. "She fainted, she clunked her head," Snyderman said. Perhaps that caused a tiny tear in the vein, known medically as the right transverse sinus. Blood would have leaked out, pooled and clotted. It's a potentially serious condition that can cause a stroke, but doctors found the clot when they did an MRI scan Sunday. "It did not result in a stroke, or neurological damage," Dr. Lisa Bardack of Mt. Kisco Medical Group in New York and Dr. Gigi El-Bayoumi of George Washington University said in a joint statement released Monday. Secretary of State Hillary Clinton is expected to make a full recovery after spending a Â fourth day in a New York City hospital for a blood clot in her head that developed following a fall and concussion she suffered last month. NBC's Anne Thompson reports. This is a standard and safe therapy for such a blood clot, according to a review published in the New England Journal of Medicine in 2005. Dr. Jan Stam of the University of Amsterdam said the clots are rare - affecting 3 to 4 people out of a million every year. Some doctors fear that blood thinners for a clot near the brain could be dangerous, but it's the best way to dissolve the clot. "More than 80 percent of all patients now have a good neurologic outcome," Stam wrote. It's also likely Clinton, who is 65, had a headache that could have tipped doctors to a potential problem - 90 percent of people who develop these clots have headaches, he said. The statement from Bardack and El-Bayoumi put an end to grumblings that Clinton was feigning illness to escape testifying about the Sept. 11 attack on the U.S. mission in Beghazi, Libya in which the ambassador and three other Americans were killed. Clinton had been expected to testify on Dec. 20 before the House of Representatives and Senate foreign affairs committees. "When you don't want to go to a meeting or conference or an event you have a "diplomatic illness." And this is a diplomatic illness to beat the band," former United Nations ambassador John Bolton told Fox News on Dec. 17. But many of her critics were wishing Clinton well this week. "A full recovery is what's important now," the New York Post wrote in a commentary. In nearly four years of office, Clinton has traveled just shy of a million miles, visiting 112 countries. She's considered a possible Democratic candidate for president in 2016. She had a blood clot in her leg in 1998, when she was first lady, and took blood-thinning drugs for several months. The Secretary of State has been undergoing treatment for a blood clot just below her ear that was reportedly caused by the concussion she suffered in mid-December. She is expected to make a complete recovery. NBC News chief science correspondent Robert Bazell reports.