CHICAGO - Doctors are testing a new obesity surgery that avoids cutting into the abdomen. Instead, the procedure involves snaking a tube as thick as a garden hose down the throat to snap staples into the stomach.

The experimental, scar-free procedure creates a narrow passage that slows the food as it moves from the upper stomach into the lower stomach, helping patients feel full faster and eat less.

Doctors say preliminary results, from about 200 U.S. patients and 100 in Europe, look promising.

After about 18 months, obese European patients have lost an average of about 45 percent of their body weight, said Dr. Gregg Nishi, a surgeon at Cedars-Sinai Medical Center in Los Angeles. He discussed the European and U.S. studies during a Chicago conference this week for digestive-disease specialists.

The procedure is only being done in the studies that recently ended enrollment. Makers of the device used in the operation plan to seek federal approval if the research continues to go as planned.

Although two studies are still under way and only brief details are being released, Nishi said results so far are slightly better than typical results from conventional stomach stapling. *