Health Service Executive Director General John Connaghan has written to Dr Gabriel Scally to clarify the protocol the HSE used to identify the original group of women affected by the CervicalCheck crisis.
Mr Connaghan said that smear tests taken up to 78 months, prior to cervical cancer diagnosis, were considered for review.
Based on HSE documents supplied to it, the Scally Inquiry had reported that smear tests taken less than 18 months before diagnosis had been excluded from the original HSE review.
This was based on the minutes of a 25 August 2015 HSE/CervicalCheck meeting, supplied by the executive to the Scally Inquiry.
"Although it is unfortunate that the 18-month figure was relied upon in compiling my report, it is welcome news that the situation has been clarified and our concerns about the adoption of an unsustainable cut-off point were not, in fact, based on the true situation", Dr Scally has said in a letter to the Oireachtas Health Committee chairperson, following receipt of the HSE clarification.
In his letter on 7 November to Dr Scally, Mr Connaghan also said the size of the original group identified for slides review, had been definitively confirmed at 293 cases, after a manual review of files by the CervicalCheck Laboratory Coordinator was completed earlier this month.
Of this 293 group, in 72 cases, no different result was determined after the slides review, resulting in the reduced figure of 221 cases.
Recently, the HSE said that four cases where there had been no diagnosis of cervical cancer, had been included in this 221 group.
In his letter to Dr Scally, the HSE Director General said that the protocol for inclusion in the smear test slides review was a minimum of one month prior to cervical cancer diagnosis and up to 78 months, prior to the diagnosis.
He said it was likely that smears taken earlier than 3-6 months before diagnosis, were taken when there had been symptoms.
Mr Connaghan said the reference in the minutes of the August 2015 meeting to 18 months was "in relation to what it would be considered a delayed diagnosis, this timeframe was referenced by Dr Gráinne Flannelly.
It was never used to exclude slides nor was it used to determine which clinicians were written to with audit results."
Dr Flannelly was the former clinical director of CervicalCheck.
Dr Scally received the HSE clarification, after appearing at a recent Oireachtas Health Committee meeting, where he and Committee members raised questions over the protocol used by the HSE.
The HSE CervicalCheck website says that the original group of affected women identified, could have got a different result from their smear test, could have been advised to have an earlier follow-up, a repeat screening test, or colposcopy.