Dozens of colonoscopies are to be reviewed at St Columcille's Hospital Loughlinstown.
The Ireland East Hospital Group say procedures performed between November 2017 and April 2018 were reviewed, as part of a quality assurance process.
As a result, it was recommended that 65 patients be scheduled for a repeat procedure.
The hospital group says it's "a precautionary measure" - and that the risk to patients is low.
The patients identified have been contacted by the hospital.
The process is expected to be completed within four weeks.
Dr Garret Cullen from the Ireland East Hospital Group said: "We acknowledge that patients may be anxious about being called for an appointment but I want to reassure them that this is purely a precautionary measure".