All complex surgery is to be transferred from the Midland Regional Hospital, Portlaoise and emergency department hours at the hospital are expected to be reduced to an 8am to 8pm service.
The transfer of surgery was confirmed today after a meeting with senior Health Service Executive officials and consultants at the hospital.
It comes in the aftermath of a damning Health Information and Quality Authority report on the safety of services at the hospital.
In a statement, the HSE said complex surgery will be moved to St James's Hospital in Dublin or to the Midland Regional Hospital, Tullamore.
The HSE said the move was being made "as the volumes are too low to maintain the requisite expertise of clinical staff."
It added that the planning process "will be done with the engagement and input of relevant staff".
Hospital would be able to cover most problems - CEO
The CEO of the Dublin Midlands Hospital Group has said the hospital would be able to cover most rare and uncommon difficult problems that might occur in maternity services through a sensible arrangement for surgical coverage.
Dr Susan O'Reilly said they would "cover off" the potential risk of urgent surgical intervention if it was needed for maternity services in the hospital.
Asked about support surgeons for obstetrics and emergency caesarian sections, Dr O'Reilly said it was an interdependency they must look at.
Dr O'Reilly said there were always 24-hour anaesthesia services in Portlaoise. She said for general obstetrics it was rare to need a general surgeon.
She said one obstetrician or a second obstetrician can usually deal with complex maternity surgeries.
But she said in rare circumstances - such as a severe haemorrhage - occasionally urgent surgical intervention was needed.
She said they would make sure through their planning processes they would cover off that potential risk.
Asked if there would be proper surgical facilities for an emergency in the middle of the night, she said that since there were in-patient beds in the hospital they would always have a surgical on-call system and there would always be surgeons available in some capacity.
Dr O'Reilly said the surgeons in Portlaoise might not be the people who would deal with a complicated vascular problem for example.
She said Portlaoise did not have vascular surgeons and neither did many of the maternity hospitals in the country.
She also said they would not be able to cover everything under the sun, but they would be able to cover most rare and uncommon difficult problems.
Asked if she could give assurances that plans for the Midland Regional Hospital Portlaoise would create a safer hospital, Dr O'Reilly she said she thinks that Portlaoise Hospital is safe.
But she said there was no health service anywhere that could say nothing could ever go wrong.
Dr O'Reilly said what the hospital continually strives to do is to make it as safe as it possibly can.
She said that one of the elements of safety is sustainability.
Dr O'Reilly said if a hospital was at risk of losing a consultant, or a couple of registrars, and then having a service that falls apart that that is not sustainable.
She said the hospital had to plan for what is the reality about patient volumes and the clinical expertise that is needed on site to deliver the care.
Anger over expected closure of Emergency Department at night
Fianna Fáil TD Sean Fleming,has said he is appalled by the expected decision to close the Emergency Department at night.
Speaking on RTÉ’s News at One, he said it was the wrong approach to take to solve problems at the hospital.
He said the hospital's emergency department is one of the busiest in the country outside the main cities, with around 30,000 people attending it each year.
Labour Senator John Whelan said he believes the HSE has deliberately used the situation where the Dáil and Seanad are not sitting this week to make the decision public.
He said ultimately the Minister for Health, his department and Government have to stand over it.
Sinn Féin TD Brian Stanley has expressed concern that the closure of the emergency department at night would mean overcrowding of the unit at peak times.
Meanwhile, Fine Gael's Marcella Corcoran-Kennedy has said she will be raising the matter with the HSE and Minister for Health Leo Varadkar.
"The first thing I want to know is why they are looking at downgrading services because clearly having an emergency unit is crucial, especially in a town the size of Portlaoise and the broader catchment is very large also."
INMO to seek discussions over implications
The Irish Nurses and Midwives Organisation has said it is to seek immediate discussions with the HSE to discuss the implications arising from the decision on surgery.
In a statement, the INMO said it fully supports the delivery of services in a manner that ensures they are of the highest quality.
However, concerns are raised over the level of overcrowding in hospitals that would receive transfers from Portlaoise.
INMO General Secreary Liam Doran said, "before any services can be relocated, to any receiving hospital, the ability of that hospital, in terms of bed capacity and staffing, to receive additional services must be examined."