Time was scheduled for acute operations during the week but sometimes acute emergencies happened outside the available blocks, she said.
"We are constantly reviewing our theatre schedules to make the very best use of our resources, but part of our purpose is also to plan for and manage the unpredictable.
"As a smaller hospital, we do not have extra theatres to manage additional acute operations at these times, therefore we have to postpone an elective procedure."
She said the hospital worked with patients to minimise the impact on work and family arrangements.
"It is difficult to be prepared for an operation and then experience a delay."
She said it would be helpful if people let the hospital know if they couldn't make it so it could make use of the time.
Chief operating officer Pete Chandler said using targets was working at Hutt Hospital where cancellations had reduced by nearly two thirds over two years. "Whilst we've only been working on this at Wairarapa for a few months, we're already seeing some great improvements on a month-by-month basis, which is very encouraging."
He said Wairarapa was below target for the year but August's data would provide a more accurate picture.
Former patient Toby Mills, who has had surgery at Hutt and Wairarapa hospitals, said Wairarapa had a "seriously slick operation" and he was impressed at how his broken arm and cut-up hand had been treated.
He was transferred to Hutt Hospital for his hand, which he said was horrible, waiting five days to be stitched up and trying to get "served" by burned-out staff: "Masterton would be my first choice if I had to have future surgeries."
Former Wairarapa resident Paula Materman was meant to have an operation on her left knee at the hospital about four years ago.
"The operation would have only taken one hour and was going to be keyhole," she said. "But I ended up getting a letter from them pretty much saying that I was not a high enough number for them to do the operation and it was cancelled."
She has since left Wairarapa but still hasn't had the surgery.
"I am a solo mother of two kids and I am living with the pain because I am too scared that another hospital is going to get my hopes up of having an operation and then just take it all away again."
The case of a Wairarapa man who was scheduled to have surgery but died before it took place is being investigated by the Health and Disability Commissioner.
The Government has been keeping the purse strings tight. The hospital is running at a deficit and since 2009 its annual increase in public funding has dropped from 4.36 per cent to 1.81 per cent for the 2014/15 year.