The Evans Surgery Center sent out letters this week to warn patients of possible infection.

The center is notifying about 1,300 patients who underwent gastrointestinal procedures with endoscopes that might not have been properly sanitized, according to the letter dated Tuesday.

An internal quality review of the medical facility on Ronald Reagan Drive discovered that the staff did not follow a manufacturer's recommendation to sanitize the endoscope for at least five minutes.

Jeff Simless, the vice president of operations at the center, confirmed the authenticity of the letter. After discussions with "leading authorities in infectious diseases," according to the letter, "the risk of disease transmission is near zero." Mr. Simless said the Center for Disease Control in Atlanta was one of the "authorities" consulted.

The center is offering free testing at any LabCorp location "to confirm that no infection was transmitted." LabCorp can be reached by calling (800) 203-0560 or visiting www.labcorp.com. The testing facility will report the results to the surgery center, which will notify patients within 10 working days.

According to the letter, a toll-free number, (888) 594-8651, was set up to answer patients' questions

As of Wednesday afternoon, at least 200 people had called the hot line or LabCorp, Mr. Simless said.

A similar warning was issued last month by the Charlie Norwood VA Medical Center. Officials said that about 1,200 patients in the center's ear, nose and throat clinic might have been exposed to infection from endoscopy equipment that was not sterilized according to the manufacturer's recommendations.