"But unfortunately, for the second time in quick succession, we will need to reschedule some elective surgery and outpatient clinics booked for those two days.
"We will be doing everything we can to make sure the patients concerned are not impacted a second time."
Simpson said patients with a planned surgery, procedure or outpatient appointment booked for the days of the strike would be contacted as soon as possible if it needed to be rearranged.
"Patient safety is always foremost in our minds so all decisions regarding rescheduling of appointments and surgery will be made with this in mind."
Patients should still come to their scheduled appointment or surgery on those days unless contacted directly to say their appointment is being rescheduled.
People with non-urgent ailments or injuries should visit their GP or after-hours clinic in the first instance.
Anyone unsure about whether they need ED care should contact their GP or call Healthline (0800 611 116) for free advice from a registered nurse.