The settings were immediately changed to five minutes, from one minute, officials said.

The 250 Cathedral Rock Road facility, near Tenaya Way and Smoke Ranch Road, is currently sending certified letters to all patients who had a colonoscopy or upper-endoscopy procedure there between Jan. 1, 2007, and Dec. 18, a spokesman said.

The surgery center's logs show that the disinfection settings might have been set to one minute starting Jan. 1, 2007, according to the incident report submitted to the licensing bureau.

"No other procedures performed at the surgery center are involved,'' said Rob Dyer, a spokesman for HCA's Far West Division, which is affiliated with the outpatient surgery center. Hospital Corporation of America, or HCA, also owns several hospitals in Las Vegas including Sunrise and Sunrise Children's Hospital.

State health officials said there would have been minimal risk of patients contracting an infectious disease such as hepatitis C or HIV because of poor cleaning of the endoscopes at the facility.

"We feel the risk is pretty close to zero, but we're not going to take that chance with our patients,'' said Dr. Ed Septimus, medical director of infection prevention for HCA. "We want to be transparent, which is a reason we are offering blood tests and counseling to patients.''

Septimus said the disinfecting of endoscopes is one step in the cleaning process. The scopes were cleaned prior to being placed in the disinfecting machine, which is a reason the risk of infection transmission is near zero, he said.

"The critical step is cleaning, and that was done,'' Septimus said.

None of the facility's gastroenterologists have reported any patient infections the past three years, the incident report says.

The facility is working with Quest Diagnostics, which operates laboratories throughout the nation, Dyer said.

A toll free telephone number has also been set up for patients, he said.

State health officials said it is unclear whether the facility will be cited for a violation because the investigation is ongoing.

They noted the facility did self-report the problem.

"This is new behavior,'' said Martha Framsted, a spokeswoman for the Nevada State Health Division.

The ambulatory surgery center's administration also notified the Southern Nevada Health District, the Centers for Disease Control and Prevention in Atlanta and the Accreditation Association for Ambulatory Health Care about the problem.

Orthopedic, radiation oncology, gynecology and some plastic surgery outpatient procedures are also offered at Specialty Surgicare of Las Vegas.

Contact reporter Annette Wells at awells @reviewjournal.com or 702-383-0283.