Prolonged winter weather has been blamed for high pressure on accident and emergency services.
United Lincolnshire Hospitals Trust last week urged people to only attend A&E if absolutely necessary as it struggled to meet demand for beds at hospitals including Boston’s Pilgrim.
Chief executive Jane Lweington said: “We’ve done a lot of planning but what’s caught us all out is the length of the winter.”
She said some operations had to be cancelled.
Inspectors are due to visit the trust’s hospitals in June as part of an investigation into high mortality rates.
There have been over 1,800 more deaths than expected in the past decade, according to research.