The North Tees and Hartlepool NHS Foundation Trust revealed in a compliance and performance report that 322 operations were cancelled for non-medical reasons due to an increase in staff being off work with coronavirus cited as a factor.
Twenty-six of these had to be cancelled on the day patients were due on the operating table.
The trust said the omicron coronavirus variant saw a surge in admissions over the festive period and staff sickness continued to remain a key challenge.
The report said: “The increased acuity of patients reporting to the emergency department, alongside gaps in staffing resources due to higher sickness and vacancy rates have compounded the impact of increased activity and the pandemic.
“Despite these pressures, clinical teams are working hard to maintain business as usual.”
Cancer was one area where performance had suffered with the number of patients waiting for treatment over 62 days said to be increasing.
More than 76% of patients did receive treatment at the trust within the 62 day timescale in November, a slight monthly improvement, but this was below the national 85% target.
A two-week rule is in place within the NHS meaning that if a GP makes an urgent referral for someone with cancer symptoms then they should be offered an appointment with a hospital specialist within two weeks of the referral.
A total of 86.5% of patients referred met this time frame in November.
But again this was below the national target of 93% and had sharply declined in the latter half of 2021.