The U.S. Food and Drug Administration on Monday recommended tougher warning labels on electric morcellators used in gynecologic surgery, but opted not to ban the devices, as critics have urged.

Power morcellators, introduced in 1993, have motorized blades that can dissect the uterus or uterine fibroids so the tissue can be removed through tiny abdominal incisions. But in some cases - the FDA estimates one in 350 - the device disseminates an undiagnosed cancer that preoperative screening tests cannot reliably detect.

The FDA urged manufacturers to add a boxed warning to their labeling that says:

The device "may spread cancer and decrease the long-term survival of patients."

The device should not be used in women who are near or past menopause, those whose tissue could be removed intact through the vagina or a relatively small abdominal incision, or those with known or suspected cancer.

During a news conference, the FDA deputy director for science, William Maisel said the benefits of minimally invasive fibroid removal with morcellation still may outweigh the cancer risks for younger women who want to preserve their fertility by leaving the uterus intact.

"But in the vast majority of women, the procedure should not be performed," he said.

Hooman Noorchashm, a cardiac surgeon at Thomas Jefferson University Hospital, denounced the FDA's action. He has led a high-profile campaign to ban power morcellators since last December, a month after the mother of their six children, anesthesiologist Amy Reed, was diagnosed with stage 4 leiomyosarcoma following a hysterectomy with morcellation.

"I can't begin to tell you how disappointing this is," Noorchashm said. "It's proof to me that the FDA is beholden to the manufacturers. I'd like to know what the FDA plans to say to the next patient who has an upstaged cancer. It's an indictment of the agency."

Of an estimated 600,000 hysterectomies done each year - 40 percent because of bleeding problems caused by fibroids - about 50,000 involve power morcellation, Maisel said.

He said that in the months since Noorchashm and Reed launched their campaign, the FDA has received about two dozen new reports of accidental spread of cancer by morcellation.

Doctors' groups have defended the value of power morcellation because traditional hysterectomy, in which the abdomen is cut wide open, increases pain, recovery time, and the risk of infection, bleeding, and dangerous blood clots.

The American College of Obstetricians and Gynecologists on Monday commended the FDA, issuing a statement that said: "Although the worsening of a malignancy as a result of power morcellation is, of course, tragic, we believe that an approach that combines deliberate patient selection criteria with robust informed consent will help protect women . . . while maintaining access to morcellation for women who would benefit from it."

The FDA's latest action builds on its warning issued in April, and a meeting that it convened in October of expert advisers.

Most hospitals - including Brigham and Women's Hospital in Boston, where Reed had her hysterectomy - have stopped using power morcellators. Johnson & Johnson's Ethicon division, the leading maker, withdrew its version from the market in July, several months after suspending worldwide sales.

Although the FDA is urging and not requiring the tougher warnings, it has asked for label revisions within 120 days.

"Our experience is that manufacturers follow FDA guidance," said spokeswoman Jennifer Rodriguez.

Noorchashm said that even if the warnings are toughened, and even if doctors inform patients of the dangers, women will be vulnerable to harm.

"Informed consent does not protect the patient," he said. "It protects the doctor and the hospital."