The field of bariatric surgery has exploded in the past decade. The number of operations performed increased ten-fold to about 140,000 per year.

But some patients have been forced to wait six months or more for their gastric bypass as many hospitals and bariatric surgeons across the country undergo additional certification.

Linda Davis, 42, is one of the lucky ones. She has health insurance that agreed to pay for her gastric bypass, but not all plans do.

"I''ve lost about 150 to 155 pounds depending on whether you use their scale or mine," says Davis, who had the Roux-en-Y gastric bypass surgery.

That's about half her weight since having the operation in April 2005. Davis says she''s thrilled.

Recently, patients covered by Medicare faced a barrier to getting bariatric surgery.

In February, Medicare decided to cover only the patients who had their procedures done at hospitals certified as Centers of Excellence by the American Society for Bariatric Surgery.

"You have to meet a certain set of criteria, ten criteria relating to the types of surgery done there, types of staff members that work with patients," explains Dr. J. Chris Eagon, a bariatric surgeon at Washington University School of Medicine.

Even the surgeons have to meet a new set of standards. Washington University''s bariatric program at Barnes-Jewish Hospital received the certification earlier this year. But many of Eagon''s Medicare patients were forced to delay their operations while that process was completed.

"This really is the first area in general surgery that there''s an outside restriction to offering of surgery," says Eagon.

There are currently three Centers of Excellence in the Metro area: the Washington University program at Barnes-Jewish Hospital, SSM DePaul Health Center and St. Alexius Hospital.

This new concept is expected to slow the numbers of bariatric surgeries performed. It could also help reduce complication rates.

Eagon thinks it's a good idea overall, but he is also concerned that limiting the numbers of certified surgeons could prevent or delay patients who need the operation from getting it.

"This is an effective therapy, a therapy that saves lives, improves the quality of life and therefore should be offered to all patients," says Eagon.

Patients can still pay for the operation themselves. It typically costs anywhere from $25,000 to $35,000.