Rep. Gabrielle Giffords (D-AZ) now "has a 101 percent chance of survival," says Dr. Peter Rhee at Tucson's University Medical Center, where Giffords is being treated after being shot in the head Saturday. (See doctors update on Giffords' health.) That in itself is something of a miracle, since more than 90 percent of people with gunshot wounds to the head die, often before they reach the hospital. But how much will Giffords recover, and when? Here's a brief prognosis, and a look at her future:

How did Giffords survive the gunshot?
Quick medical intervention and a healthy dose of luck. Giffords' intern, 20-year-old Daniel Hernandez, who'd been working for the congresswoman for just five days and had previously trained as a nurse's assistant, rushed to her side. He propped Giffords up to prevent her from choking on her own blood, applied pressure to the wound to stem blood loss, and waited for the paramedics to arrive. "It was probably not the best idea to run toward the gunshots, but people needed help," he recalls. State representative and hospital physician Matt Heinz says Hernandez's actions saved Gifford's life.

How was she lucky?
The bullet passed through only the left hemisphere of her brain, avoiding the critical neural connections in the middle, and appears to have left intact the parts of the brain that control hearing and significant motor skills. Giffords also benefits from the rapid advances in treating brain injury that have come out of the wars in Iraq and Afghanistan, both of which have produced many cases of this "signature" injury of modern warfare.

How fully will she recover?
Nobody can say at this point. It's conceivable that she could make a full recovery; there is also a danger she could lapse into a vegetative state. "I hope that she's not and I don't think she will be in a vegetative state," says Rhee, but at least "I know that she's not going to die." Doctors are cautiously optimistic, because she can breathe on her own and has given thumbs-ups and other responses that require a high level of cognition. "She has no right to look this good, and she does," says Dr. Michael Lemole, Giffords' neurosurgeon.

How long will her recovery take?
Anywhere from several months to a year and a half or longer, experts say. It depends largely on how badly her brain was damaged, and the effects of that damage, which doctors won't be able to assess for weeks. "She is going to take her recovery at her own pace," Lemole says.

What are doctors most worried about?
"The two most obvious questions," says Casey Schwartz in The Daily Beast, "are whether her ability to speak has been disrupted and whether she is paralyzed on the right side of her body," which is controlled by the left half of the brain. Doctors also don't know yet whether the bullet damaged her vision or other senses. The biggest initial risk in brain injuries, though, is swelling — about half of her skull has been temporarily removed as a precaution — and doctors are optimistic that Giffords has dodged that problem during the most vulnerable period.

What if Giffords can't return to Congress?
Congress could adopt a resolution declaring her seat "vacant," as it did in 1981 with Rep. Gladys Noon Spellman, who fell into a coma before taking her oath of office. But there is no set procedure in the Constitution, federal law, or Congress to deal with incapacitated members, according to the Congressional Research Service. If Giffords' seat is declared vacant, Arizona law stipulates that a special election would have to be called within 72 hours, and the winner would serve the remainder of Giffords' term.

Sources: Huffington Post, Politico, New York Times (2), CNN, Arizona Republic, USA Today, Daily Beast, KOLD News