A new device that opens blocked fallopian tubes with a tiny balloon can offer a simpler and cheaper method for helping infertile women become pregnant, doctors reported Wednesday.

However, the technique is designed for a particular type of blockage, present among only 10 percent of the estimated 1 million American women who have blocked fallopian tubes.The procedure, which requires neither surgery nor general anesthesia, is similar to the use of balloons to open the clogged arteries of heart patients, according to the report in today's Journal of the American Medical Association.

The balloon is mounted on a flexible tube called a catheter and threaded through the womb into one of the fallopian tubes, which connect the uterus to the ovaries. Once the balloon is in place, doctors inflate it to open the passage.

Dr. Edmond Confino, the study's lead author and director of education in obstetrics and gynecology at Mount Sinai Hospital Medical Center in Chicago, said the procedure could reduce by two-thirds the cost of treating women with blockages, who now usually choose between microsurgery or test-tube fertilization.

The procedure is expected to cost a third as much as test-tube fertilization, which totals about $6,000, succeeds about 20 percent of the time and results in only a single pregnancy. Microsurgery, in which the patient's abdomen is opened, typically costs up to $10,000, Confino said.

A surgeon not involved in the study said he believes the technique offers no significant advantages over still another method, simple catheterization. Simple catheterization uses the flexible tube itself to clear the blockage.

The device is designed to treat proximal tubal occlusion, or blockage of a tube near the point where it enters the uterus.