A vigilant member of staff who voiced concerns is behind a review of colonoscopies involving 65 patients at a Dublin hospital.
St Columcille's Hospital, in Loughlinstown, has now asked the patients to return for a repeat procedure.
A colonoscopy is an internal examination of the bowel which is used in the diagnosis of cancer and other conditions.
The staff member was worried that a complete photo- graphic record of the end section of the bowel was not obtained.
This led to a look-back at 160 colonoscopies carried out there by a doctor between November and April.
"It was discovered that in 65 cases there was not a complete photographic record of the end section of the bowel," a spokeswoman for the hospital said.
"This photographic record is evidence that the colonoscopy was completed.
"Hence, for best practice, it was decided to rescope those 65 cases."
All 65 patients have been contacted, but it will be some weeks before they all receive a repeat procedure as some are on holiday.
"St Columcille's Hospital, as part of a quality assurance process, undertook a review of colonoscopies performed at the hospital between November 2017 and April 2018," the spokesperson added.
Dr Garret Cullen, clinical lead for endoscopy at Ireland East Hospital Group, said the measure was precautionary and the risk to patients is low.
"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, appointments are currently being scheduled and we expect this process to be complete within four weeks," he said.
The doctor involved in the original work was employed on a seasonal basis at the hospital and no longer works there.
Asked where the doctor is working now, a spokeswoman said she had no further comment to make.
"The doctor was employed on a non-permanent basis, this arrangement is complete and the consultant is no longer at St Columcille's," she said.
"We have no further comment to make regarding the consultant.
Questioned on the protocol used to contact patients, she said: "We would like to apologise to all patients who are involved in this recall and understand that this has put undue stress and worry.
"It is, however, very important that we contact patients involved as soon as possible and ensure that they have their rescope as quickly as possible.
"In this instance a letter was sent out to each of the patients involved with a contact number at the hospital.
"The morning after the letter was sent to patients, staff at St Columcille's Hospital telephoned each patient as a follow up, to explain the process and answer any questions the patient may have."
She said she was aware of the distress caused to people concerned.
"We sincerely apologise to them and appreciate that this has caused worry to them and their families.
"We hope to make this process as easy as is possible on the patient and ensure that they are seen quickly," she said.