The health insurer Aetna is ending most coverage of hysterectomies performed with a once-popular device that has drawn warnings from federal regulators over a risk for spreading cancer. 

The nation's third-largest health insurer said Tuesday that, as of May 15, it will curb coverage of power morcellation in hysterectomies or for removing uterine fibroids "because the safety and efficacy of this approach has not been demonstrated."

Aetna Inc. will make exceptions for pre-menopausal women who want to maintain their fertility and for whom another treatment would not be effective. The Hartford, Connecticut, company also will still cover the procedure in patients for whom the use of another approach would be a life-threatening risk.

A hysterectomy is the surgical removal of the uterus. The procedure is used as a treatment for a variety of conditions, including severe endometriosis, chronic pelvic pain, and some cancers.

Laparoscopic power morcellators are used to remove uterine fibroids or the entire uterus in less-invasive surgeries than standard abdominal procedures. Surgeons use the tools to grind and shred uterine tissue so it can be removed through a small incision in the abdomen.

The Food and Drug Administration warned last fall that the devices should not be used in most cases because they can spread undetected cancers.