The surgical instruments went through two-thirds of the sterilization process, but didn't go through the final steam cleaning. That steam would have turned sensors from blue to black.
When the doctors saw the blue sensors on the instrument racks, they knew they had a problem.
Doctors and administrators at Cape Fear Valley Medical Center have implemented new sterilization procedures after three trays of surgical instruments were found that had not been completely sterilized.
Administrators say 160 patients could have come in contact with unsterilized equipment.
"We mailed letters to all 160 patients that were identified," Cape Fear Valley Medical Center Dr. Eugene Wright said. "Also on October 15 we voluntarily self-reported to the State of North Carolina the situation."
Doctors say at this point there are no reports of symptoms of infections amongst the patients.
Doctors say the instruments go through a four hour sterilization process that includes special sensors that change from blue to black after instruments are sterilized.
"On the inside of here there are these filters and they are actually little black dots on these filters that show that it has been sterilized, and those are also on the top and the bottom," Cape Fear Valley Medical Center Dr. Leo Davidson said. "And there's this indicator right here, and the black stripe means it's sterile."
The state has recommended the hospital be placed on "Immediate Jeopardy" status, which could lead to the medical center losing payments from Medicare and Medicaid that accounts for nearly 70 percent of the hospital's revenue.
"We expect Medicare on sight within the next 21 to 23 days to remove that Immediate Jeopardy," Cape Fear Valley CEO Joyce Korzen said. "We have taken all steps at this point to basically improve anything that was identified last week, Wednesday and Thursday."