Bed-blocking is also clogging up space across Scotland’s NHS, with more than 1,000 patients stuck in hospitals when they were ready to go home in May.
Labour has stepped up calls for Health Secretary Shona Robison to be sacked in light of the figures which have been branded “totally unacceptable”.
The Cabinet Secretary has insisted that the NHS “works hard” to keep cancellations to a minimum and that the overall postponement rate is at an all-time low.
A total of 512 operations were scrapped in May due to capacity issues, up from 490 the previous month. The worst month this year was January when 704 operations were cancelled.
A total of 141,638 operations were carried out in the first five months of this year, health service figures yesterday showed. But 2,912 planned operations were cancelled between January and May due to capacity reasons, an average of 19.2 per day.
Labour’s health spokesman Anas Sarwar said: “These official figures once again reveal the extent of the SNP’s mismanagement of our NHS.
“An average of nearly 20 operations are being cancelled every day so far this year – that’s almost 3,000 patients since January.
“This is simply unacceptable. The SNP has left our NHS staff under-valued and under-resourced, while patients are facing delay after delay.
“It is clear that SNP Health Secretary Shona Robison is now totally out of her depth - she created this crisis and she can’t be the one to fix it.
“Nicola Sturgeon must reshuffle her Cabinet and get back to the day job of fixing the mess the SNP has made of our NHS.”
The figures reveal that 4,804 operations were also cancelled in the five months to May by the hospital due to concerns about the health of the patient involved, while 4,979 were cancelled by the patients themselves.
A further 405 procedures were postponed for unspecified reasons, the figures show.
Ms Robison said the 29,997 procedures carried out in May show that there were an average of almost 1,000 operations per day carried out in Scotland’s hospitals.
The total of 13,100 axed operations – for all reasons – represents the lowest ever rate of overall cancellations since the statistics were created, she added. The cancellations due to a lack of hospital staff or space was just 1.7 per cent, she said.
“Boards work hard to keep cancellations to a minimum, and we’ll continue working with them so we see sustained improvement,” she added.
“I am confident that the recently announced extra £9 million to improve patient flow through hospitals this year will help us continue to reduce delays.”
The figures show the picture is improving in Scotland’s emergency departments.
There were 150,442 patients seen at Accident and Emergency (A&E) services in Scotland throughout May.
Of these, 94 per cent were seen within four hours, which is just short of the national target of 95 per cent.
But just over 700 patients –about 22 a day – were forced to wait more than eight hours, while 96 spent more than 12 hours in an A&E department. Fewer than a quarter of attendances (23.7 per cent) led to an admission to hospital.
The most recent weekly A&E figures covering the seven days up to 25 June found that 94.5 per cent of patients were being seen within the four-hour target, but 83 people were forced to wait more than eight hours.
Ms Robison has previously pledged to “eradicate delayed discharge”, also known as bed-blocking.
But the latest figures show that this still remains an issue in the NHS. In May, 39,651 days were spent in hospital by people whose discharge was delayed. This is equivalent to an average of 1,279 beds occupied per day in May 2017. In April, the daily average was 1,364.