Secretary of State Hillary Clinton is suffering from a blood clot located between her brain and her skull, behind her right ear, her physicians said Monday, describing the location of the clot for the first time since she was hospitalized on Sunday.

She didn't suffer a stroke or sustain any neurological damage, said her doctors.

"In all other aspects of her recovery, the secretary is making excellent progress and we are confident she will make a full recovery," Dr. Lisa Bardack of Mt. Kisco, N.Y., and Dr. Gigi El-Bayoumi of George Washington University said. "She is in good spirits, engaging with her doctors, her family, and her staff."

Hillary Clinton Agence France-Presse/Getty Images

The blood clot is in a vein that experts said drains blood from the brain and is in an area known as the right transverse sinus, which the physicians described as a space between the brain and skull, behind the ear.

They said the blood clot was discovered Sunday in a "routine follow-up" visit. They said Mrs. Clinton would be released from the hospital once a proper dosage of blood thinners has been established. She was being treated at New York-Presbyterian Hospital/Columbia in New York City.

State Department officials before Monday afternoon's statement had declined to say where the blood clot was located.

The clot was the latest health problem to confront Mrs. Clinton in recent weeks. She became ill with a stomach virus during a European trip early in December. That virus led to what officials described as dehydration and caused her to faint, fall and suffer a concussion. The blood clot was discovered over the weekend.

Dr. Lori Shutter, a neurologist and critical-care doctor at the University of Pittsburgh Medical Center, said Mrs. Clinton was fortunate that the clot was in this particular vein, because there are two such veins, one behind each ear. With one blocked, the second is able to continue draining used blood from the brain.

Without that backup, the clot could have led to a "venous stroke." In that condition, the brain cannot properly drain itself of blood, resulting in a buildup of pressure. Because of the pressure, the brain wouldn't be able to accept sufficient amounts of oxygenated blood from arteries to sustain the tissue—hence a stroke.

Dr. Shutter said Mrs. Clinton's clot could well have been caused by the fall and concussion earlier in December. The fall could have led to a hairline fracture of the bone surrounding the vein, or could have caused inflammation within the vein. Either way, Dr. Shutter said, a clot could have occurred.

Dr. Shutter, who isn't involved in Mrs. Clinton's care, said the secretary likely will be on blood thinners for months.

Venous strokes more typically occur because of a clot in another vein, called the superior sagittal sinus. This is because there is only one such vein and any blockage there could prove more critical.

A venous stroke is considered generally less severe than the most common kind of strokes, which are caused by a clot in an artery, which blocks blood flow to the brain and can kill brain tissue.

By contrast, a venous stroke can cause some minor weakness or confusion, said Dr. Shutter.

The disclosure of the location of Mrs. Clinton's blood clot came near the end of the day, after State Department officials had refused to elaborate on her condition. It wasn't clear when physicians determined the secretary had avoided a stroke or any neurological damage, or whether that determination contributed to the delay in the release of details about her condition.

Earlier in the day on Monday, hospital executives referred all questions about Mrs. Clinton's condition to the State Department, where officials wouldn't respond to questions.

The latest setback may affect plans for Mrs. Clinton to testify before Congress about the Sept. 11 assault on a U.S. diplomatic post in Libya that claimed the lives of four Americans, including the U.S. ambassador, and resulted in sharp criticism of her agency.

She initially had planned to testify Dec. 20, but postponed that appearance because of her concussion, promising before her hospitalization Sunday to appear before lawmakers in January.

—Julian E. Barnes and Jay Solomon contributed to this article.

Write to Thomas M. Burton at