The Health Service Executive (HSE) is launching a rapid review process, after around 800 women did not receive the results of their CervicalCheck tests in recent months.
One of the labs - Quest Diagnostics - based in the US state of Virginia have delayed issuing cervical screening results to some women and their GPs, due to IT problems.
This relates to how result letters were electronically triggered.
The HSE says the issue appears to "primarily affect approximately 800 women" who were having HPV tests rechecked - dating from late 2018 until June 2019.
However, the Department of Health was only told earlier this week about the IT glitch.
The HSE says it has known since February about the issue.
It also says it is aware of a "very small number of people" affected outside of this recheck group, and is following up on those cases.
HSE CEO Paul Reid says: "In response to information emerging over recent days, I have decided to commission an immediate rapid review of this incident.
"This review will examine in detail how the communication process for providing results to women was planned and managed.
"I want this work to commence quickly and be completed in a timely manner, led by a chairperson external to the HSE."
"While this review is ongoing, we will continue to update the women involved as planned, and to work with Quest Diagnostics to get to the bottom of what has happened, what needs to be done to resolve these problems."
Dr Colm Henry, HSE chief clinical officer, adds: "We will ensure that the results are communicated to all women, through their GPs, as soon as is possible.
"This is to ensure that they have full access to their results, as should have happened from the outset."
Details of the chairperson of this rapid review and its terms of reference will be announced early next week.
The Quest Diagnostics facility currently only performs HPV testing for CervicalCheck, which is just one part of the overall cervical screening test process.
CervicalCheck has instructed Quest Diagnostics to immediately dispatch all outstanding results from this group to their GPs.
This means that the people affected should either have their results already from their GP, or will be able to get them in the next day or so.
CervicalCheck says it will also follow up with all those people again this week and next week.
Fianna Fáil health spokesperson Stephen Donnelly earlier said the health service was aware of the issue in June – yet only informed the public on Thursday night “within hours of the Dáil going into recess.”
“The timing from the HSE, I have to say, is deeply cynical,” he said.
“They knew about this in June and they appear to have only informed the department within hours of the Dáil going in to recess.
“I don’t think that is an appropriate response given the very serious issue around non-disclosure that have dogged CervicalCheck for the last year.”
In a statement on Thursday, the HSE said the issue was only uncovered after a woman contacted the Department of Health to warn that she had not received her results.
It said it wrote to the women affected to inform them on July 1st and advised them to contact their GPs to get their results.
However, it emerged in recent days that a number of GPs have also not received expected result reports. On Thursday, Quest Diagnostics promised to manually issue the result reports to all the doctors involved.
The lab involved is based in Chantilly and is one of the facilities brought in to increase the capacity of the screening service as it deals with a large backlog of samples.
The HSE said the facility did not implement a critical IT update in time to give it capacity to transfer results to the programme’s Cervical Screening Register – and inform women and their doctors that their results were ready.
“We sincerely apologise again for this IT issue and the confusion it has likely caused to individuals concerned,”the HSE said.
It said it was confident the lab is now capable of generating the electronic results and Quest Diagnostics has pledged to ensure that all necessary IT updates and testing will be finalised in the next two weeks.
Additional reporting: Jack Quann