A blood clot’s danger depends on where it is

AP

Blood clots like the one that Secretary of State Hillary Rodham Clinton is being treated for following her recent concussion can occur for a host of reasons.

How serious a clot is depends on where it is and why it formed. In a statement Monday, Clinton’s doctors say her clot was located in a vein in the space between the brain and the skull behind the right ear

WHAT THEY ARE: Blood pools and thickens into a clot after an injury or because of a heart problem, clogged arteries or other condition. Clots also can break off and travel to another part of the body.

WHERE THEY OCCUR: In leg veins (called deep vein thrombosis) or in blood vessels in the neck, brain or lungs. Leg clots are a common risk after someone has been bedridden. Clots are most dangerous when they travel to the lungs, a potentially life-threatening situation, or to the brain, where they can cause a stroke.

RISK FACTORS: High blood pressure, diabetes, birth control pills, pregnancy, stroke, recent surgery, prolonged sitting, circulation problems and heart problems - especially an irregular heartbeat called atrial fibrillation - raise the chances of developing a blood clot.

TREATMENT: Sometimes a blood thinner such as warfarin (Coumadin) is prescribed to allow the clot to dissolve by itself over time and prevent new ones from forming.

CLINTON’S TIMELINE TO ILLNESS

For nearly a month, Secretary of State Hillary Clinton has been battling health ailments stemming from what State Department officials said was a stomach virus contracted during an overseas trip at the beginning of December. Here is a chronology:

Friday, Dec. 7: Clinton returns from a five-day trip to Prague, the Czech Republic, Brussels, Dublin, and Belfast, suffering from what officials later said was a stomach virus, which also affected other members of her traveling party.

Monday, Dec. 10: State Department postpones Clinton’s planned trip to the Middle East by a day because of the virus. A centerpiece of the trip was a “Friends of Syria” meeting in Morocco on Dec. 12.

Tuesday, Dec. 11: State Department cancels Clinton’s trip to Morocco and the Middle East, sending Deputy Secretary of State William Burns instead.

Saturday, Dec. 15: State Department announces that, as a result of the stomach virus, .Clinton had become dehydrated and fainted earlier in the week, suffering a concussion when she fell. Officials would not say exactly when the fall occurred or where she was when it happened.

Lawmakers said the developments meant Clinton would miss Dec. 20 hearings in the House and Senate about the Sept. 11 terrorist assault against the U.S. diplomatic post in Benghazi, Libya.

Tuesday, Dec. 18: State Department spokeswoman Victoria Nuland said Clinton is “on the mend, she’s going to be absolutely fine.” Nuland said the secretary of state was working at home and was writing letters and emails and making phone calls.

Thursday, Dec. 20: Top Clinton aides Burns and Thomas Nides testify before House and Senate committees on Benghazi about an independent review that found glaring errors at the State Department.

Sunday, Dec. 30: State Department announces that in a follow-up exam, doctors discovered a blood clot and that she has been hospitalised in New York City for treatment with anti-coagulants. State Department officials would not say where the clot is located. She is expected to remain in the hospital at least until Tuesday.

Monday, Dec. 31: In an update, Clinton’s doctors said she is suffering from a blood clot located between her brain and her skull, behind her right ear, describing the location of the clot for the first time.