CLEVELAND - Surgeon Maria Siemionow was getting ready for bed a few weeks ago when she got the call she had been awaiting for 20 years.

A woman had died, and her family would let her be the donor for the first face transplant in the United States, the Cleveland Clinic plastic surgeon was told.

And that meant that Siemionow's patient, a woman who had lost most of the middle of her face several years ago in a violent trauma, might regain some semblance of a normal life.

By the next afternoon, a team of surgeons had assembled, doctors recounted yesterday at a news conference describing the surgery.

The surgeons started by removing 80 percent of the donor's face, from her lower eyelids down through her upper lip. They checked their progress against an exact 3-D model of the recipient's face, made from computerized X-ray scans.

In an adjoining operating room, another team began to remove the scar tissue that had covered the center of the recipient's face.

For years, she had lived with vision in only one eye, no cheekbones, no nose, no upper jaw and no upper lip. She could see only dimly, could not eat without a feeding tube, could no longer smell, and had difficulty communicating.

She was courageous enough to go out in public, Siemionow said, but "she often suffered humiliation. People called her names. Children were scared of her and ran away." Siemionow and her colleagues were hoping to change that.

Eleven hours after surgery began, doctors positioned the donor's face over the same parts of the recipient's face and began attaching skin, muscle, veins, nerves and bone.

The team had to connect five major blood vessels, two sets of nerves, with intervening nerve grafts, all of the muscles and bone.

"It was like a jigsaw puzzle you had to fit into the appropriate position and put together," said Daniel Alam, a principal plastic surgeon on the case.

With operations like an appendix removal, Alam said, surgeons do about the same procedure on every patient. But in these kinds of transplants, he said, "it becomes like an artistic project for each individual patient." By 4:30 p.m. on the day after they started - 22 hours in total - the surgical teams finished.

Later, as the patient emerged from the anesthetic, one of the first things she did was run her hands over her face, confirming that she had a nose, a jaw and cheeks for the first time in years.

Then, she gave the team a thumbs-up sign.

The procedure in Cleveland is the world's fourth face transplant and the largest in skin area.

Experience with those procedures has shown the first month is the critical period to see if the person's body will reject the transplanted tissue.

So far, the woman in Cleveland has had no rejection, though she will have to take immune-suppressing drugs indefinitely.

Unlike many organ transplants, those involving the face are not life-saving, but rather enhance quality of life. So medical ethicists have questioned whether they should be done.

The Cleveland Clinic team argued that in cases of severe disfigurement and interference with normal functioning, the benefits outweigh the risks.

The clinic's fact sheet also noted that every face-transplant candidate must have enough viable skin elsewhere on the body to replace the transplanted tissue if it is rejected.

Eric Kodish, the team's ethicist, noted that the clinic would never do a face transplant for "cosmetic enhancement," and hopes no one would ever attempt one.

Even though the clinic has emphasized that restriction since it got internal approval four years ago to do face transplants, it still received inquiries from people with minor facial scars or blemishes, Siemionow said.

"They were thinking we would do this to beautify them," she said.

For the same reason, Kodish said the recipient would never be shown a photograph of the donor's face, because it would suggest the donor's appearance was a factor.

Besides, the doctors noted, face-transplant recipients are unlikely to look like the donor because of their underlying muscle and bone structure, and particularly if they have been disfigured.

Neither the donor family nor the recipient wanted personal details revealed, so the doctors would not talk about how the donor died or what kind of trauma the recipient had experienced.

The donor was a woman of the same race, Siemionow said, and was roughly the same age. She also donated her kidneys and liver to other patients.

The recipient will have months of rehabilitation. In three to six months, she should regain significant feeling and motor control in the new face.

"There will be a lot of work to do," Alam said, "learning how to smile, to eat, and even learning how to blink with hybrid eyelids, because her upper eyelids are hers and the lower ones are from the transplant."