A total of 1,767 operations were cancelled at the last minute at South Tyrone Hospital over the past three years, latest figures have revealed.
The number was even greater at Craigavon Hospital with 2,066 patients missing out on treatment over the same period.
According ot the Department of Health, the figures refer only to operations cancelled within two days of the appointed time.
The Royal Group of hospitals had the highest number of dropped operations at 5,637.
Former Health Minister and UUP Assembly member Michael McGimpsey said the scale of the problem “laid bare” the crisis facing the NHS.
There was a public outcry in January when all five of the north’s health trusts took the unprecedented step of cancelling planned operations due to massive A&E pressures.
Concerns were raised at the lack of transparency across the sector, with many patients awaiting surgery complaining at the lack of communication about their revised dates for serious operations, such as hip replacements.
DUP health minister, Simon Hamilton said the cancellations related to a range of issues, including an overrun of theatre lists, emergency cases taking priority and equipment failure.
Mr Hamilton also noted that in some cases patients cancelled themselves or were deemed medically unfit to undergo a procedure.
But Mr McGimpsey noted that all hospitals across the north had been affected by the problem, which he branded “inhumane” given the lengthy delays for first assessments with a consultant.
“Making people wait for months to be even given an appointment, then for several more for a date of surgery is bad enough in the first place, but then cancelling that operation often at the last moment is downright inhumane,” he said.
A department spokesperson said the figures include cancellations due to both clinical and non-clinical reasons, as well as patient cancellations. “Non-clinical reasons include list over-run, emergencies/trauma, etc. while clinical reasons are those where the patient was clinically unsuitable to undergo the procedure, though these lists are not exhaustive.”