The Colchester East Hants Health Authority is telling more than 250 patients and their doctors that the products used to disinfect transrectal ultrasound probes were not recommended by the manufacturer.
Procedures involving the probes began in 2009.
They were stopped on April 15 and resumed the following month after staff received additional training.
A review by the health authority's medical specialist says it's unlikely anyone was exposed to serious infection because the probes were still cleaned between patients and covered with a protective sheath.
Patients are being advised to contact their doctor if they have any concerns.