Dozens of colonoscopies are to be reviewed at St Columcille's Hospital, at Loughlinstown in Dublin.
The Ireland East Hospital Group say colonoscopies performed between November 2017 and April 2018 were reviewed, as part of a quality assurance process.
As a result, it was recommended 65 patients be scheduled for a repeat procedure.
The hospital group says this is "a precautionary measure" - and that the risk to patients is low.
The patients identified have been contacted by the hospital.