President Cristina Fernandez's government was in uncharted territory Sunday after doctors ordered the Argentine leader to take a month's rest because they found blood on her brain from a head injury.

While experts called the prescription good medicine, it could prove politically risky for her to leave the campaign trail just three weeks before nationwide elections determine control of Congress. Fernandez has stumped hard for her party's candidates, and both pro and opposition forces have focused on her central role managing the government and economy.

The presidential office broke a weekend of near-total silence with a three-paragraph news release summarizing Fernandez's medical condition late Saturday, more than nine hours after she entered a hospital for tests.

There were no updates as of Sunday evening, and no official word on whether she would formally put the government in the hands of Vice President Amado Boudou, who called off a trip to the Cannes film festival to rush back to Buenos Aires.

Parlamentario.com, a media site that closely follows Argentina's congress, reported that "sources close to Boudou" said he "is already in charge," but that any formal declaration would come from Fernandez's spokesman, Alfredo Scoccimarro.

Fernandez, 60, has been a tireless campaigner since her opponents made a significant show of force in the August primaries — results that prompted opposition media to write about the beginning of the end of a populist government that began with the 2003 election of her late husband and predecessor, Nestor Kirchner.

The Oct. 27 elections could shift the balance of power in Congress, possibly taking away the votes she needs to rule by emergency decree during the final two years of her second term.

Scoccimarro went on national television at 10 p.m. Saturday to read the three-paragraph statement signed by the president's doctors. He took no questions.

No details were released about the cause of the previously undisclosed "skull trauma" the doctors said Fernandez suffered Aug. 12, one day after the primaries. Neither was there an explanation of why the injury wasn't disclosed earlier, even though the doctors say she had a CAT scan done on her brain in August during what was described as a gynecological visit.

Fernandez has suffered from a variety of ailments, and doctors have periodically ordered her to rest due to chronic low blood pressure. She also has a history of trying to keep her medical condition private until she can share good news. Questions abounded at first about her thyroid surgery in January 2012, when she had both glands removed fearing they were cancerous. Tests later showed no presence of cancerous cells.

Her doctors' statement said that the brain scan found nothing wrong and that initially she suffered no symptoms. They said she went in for more tests Saturday after experiencing an irregular heartbeat as well as headaches, so they looked at her skull again.

"The president had a cardiovascular study done in the Fundacion Favaloro and given that she had head pain, they did neurological studies, diagnosing a 'chronic subdural collection,' and they ordered her to rest for a month," Scoccimarro read.

The doctors added that they will closely watch how the bleeding evolves using imaging technology while Fernandez rests.

"Generally such patients are operated on with positive results and without any neurological problems," Dr. Rolando Cardenas Sanchez, a brain surgeon and director of the stroke committee at the Argentine Cardiological Society, told The Associated Press on Sunday.

According to the U.S. National Institutes of Health, the surgery involves drilling small holes in the skull to drain the liquid and relieve pressure to reduce or prevent brain damage.

Brain experts interviewed Sunday cautioned that without any information beyond the brief statement from the president's doctors, they could not analyze her situation in detail. But Cardenas Sanchez said the general description suggests that her chances were good for a full recovery.

"At the time of the blow, the tomograph or the diagnostic exam can appear normal because it doesn't appear immediately. This chronic subdural hematoma can appear gradually and it pushes on the brain because the bone doesn't move, and so inside the skull it pushes on the covering of the skull and produces pain," Cardenas Sanchez said.

Neurosurgeon Nicolas Arranz gave a similar review to the state-owned news agency Telam.

"In 95 percent of such cases, it's the product of a blow that could have been minor, inconsequential, and not necessarily a heavy blow," he said.

"We're talking about an injury outside the brain, not an accidental stroke, which is another kind of injury ... Anyway, these symptoms generally resolve themselves with a very low-risk operation in which the clot is removed."

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Associated Press writer Michael Warren reported this story in Buenos Aires and Belen Bogado reported from Asuncion, Paraguay.