WASHINGTON (AP) -- The government has approved the first nonsurgical method of sterilizing women, a tiny device called Essure that could transform the way many women end their childbearing years.

Scientists long have tried, and failed, to develop a way to sterilize women without surgery; sterilization remains the most widely used form of birth control. More than 180 million women worldwide have had the procedure performed, including an estimated 700,000 Americans a year.

Today, sterilization is performed through an operation called tubal ligation, where doctors cut and tie the fallopian tubes to keep eggs released by the ovaries from reaching the uterus. It requires either conventional surgery, with large incisions, or minimally invasive surgery in which doctors work through small cuts in the abdomen. It typically requires general anesthesia.

Essure, in contrast, requires no cutting and only a local anesthetic in a half-hour procedure that promises to block the fallopian tubes as effectively.

"This is a very exciting, innovative method," said Dr. Vanessa Cullins of Planned Parenthood. "This method is a form of permanent birth control, so the woman must be sure that she does not ever want to become pregnant."

If that is the case, women probably will find Essure "much more convenient" than standard sterilization, because it can be performed in a gynecologist's office, she said.

The device looks like a tiny spring. Doctors use a thin tube to thread one Essure device up the vagina, into the uterus and then into each fallopian tube. Flexible coils temporarily anchor it inside the tube. Dacron-like mesh embedded in those coils -- material widely used in medical procedures -- irritates the tube's lining to cause scar tissue to grow that eventually permanently plugs the tube.

The catch: It takes three months for the scar tissue to grow.

So in approving Essure on Monday, the Food and Drug Administration cautioned that women must use another type of birth control during those three months, then return for testing to ensure the scar tissue has fully blocked her tubes.

That's a crucial check, because not all women can be implanted successfully. In one study, doctors failed to block both tubes fully on the first try in about one of seven women, the FDA said. The test, performed at outpatient radiology clinics, consists of an injection of dye into the uterus followed by an X-ray to be sure the tubes are blocked.

In studies of more than 600 women, followed for a year, there so far have been no pregnancies in those whose Essure devices were implanted successfully.

The FDA did, however, require Essure's maker, Conceptus Inc., to continue studying those women for five years to ensure no long-term problems crop up.

Conceptus, of San Carlos, Calif., planned to begin training physicians to implant the Essure device this weekend. The company expects to have enough physicians that Essure will be offered nationwide by March.

It will cost about the same as traditional tubal ligation, about $2,500, a company spokeswoman said.

Copyright 2002 The Associated Press. All rights reserved.