Cancelled operations due to winter pressures in hospitals are becoming "the norm" not the exception in Wales, a leading surgeon has warned.
Tim Havard, of the Royal College of Surgeons, said Wales is braced for a repeat of last winter’s high demand, which was the busiest he had known.
Numbers of postponed operations rose to 84,477 in 2015/16, new figures show.
There has also been a jump in patients not turning up or postponing their own surgery at short notice.
The proportion of planned operations cancelled for non-medical reasons – such as beds not being available – has fallen (40.2%).
But those as a result of patients cancelling or not turning up to their appointment has risen to 41,031 (48.6%).
The rest (11%) are due to surgery being cancelled for medical reasons such as the patient not being fit enough.
The previously unpublished figures show with more than a third of a million new routine surgery cases in Wales last year, patients have a one in four chance of the operation being cancelled for one reason or another.
A Welsh Government spokesman said: "While the health service needs to do more to prevent non-clinical postponements, we want to create a shared responsibility NHS where people attend their appointments and let the NHS know as soon as possible if a procedure is no longer needed so their space can be re-allocated to another person who needs treatment."
Conservative health spokeswoman Angela Burns AM said it was the "height of selfishness" and unacceptable for those patients who simply did not turn up on the day.
"However, I don’t like the Welsh Government’s attitude putting the emphasis all down to patients, it’s a logistics problem we’ve had for years and we should be able to solve it by now."
Mr Havard, a consultant surgeon in Cardiff, said last winter was "extraordinarily difficult in terms of emergency pressures" and the most difficult he could remember, with the knock-on effect still being felt in June.
He said the lack of capacity to manage routine surgery was the biggest symptom and led to a large number of cancellations.
There was also a rise in demand from patients in their 80s and 90s being admitted to hospital.
"I cannot be confident we’re not going to have more winter pressures this year," he said.
"It’s difficult to predict but I don’t see anything that is radically different from last winter. We’re under pressure at the moment – at the end of September.
"We are functioning in terms of our elective operations but more pressure will mean it is likely we will run into similar problems this winter."
He said in terms of a long term fix there either needed to be more capacity or "difficult decisions" such as splitting work between hospitals in areas – so one does emergency services while the other does routine surgery.
"In the past we used to cancel elective operations just in extremis, when we had particular pressures, and that was unusual.
"I think that’s become more the norm and we use it as the pressure outlet."
Plaid Cymru health spokesman Rhun ap Iorwerth said cancellations because of lack of beds, staff and problems with equipment were problems that the Welsh Government "had to get to grips with."
But he also said people had to "understand the consequences for their actions if they don’t turn up for their operations."
He said alongside education, there needed to be better communication between the NHS and the patient so they realised the importance of their treatment and the details of when it was to take place.
Health Secretary Vaughan Gething, who attended a winter planning meeting on Wednesday, said everyone could play a part in reducing pressures.
"If you are eligible for a free flu vaccine, it’s worth making plans to get it soon so you are protected throughout the autumn and winter this year," he said.
"If you do get sick and need medical attention, take a look at the Choose Well website and app that explain what each NHS service does.
"In many cases people go to emergency units when they could receive advice, be seen and assessed in a minor injuries unit, GP surgery or a pharmacy."