Lancashire MP Eric Ollerenshaw has slammed the loss of vascular services at the Royal Lancaster Infirmary, which serves people from the Garstang area.
The NHS trust which runs the hospital has failed in its bid to continue specialist vein and artery surgery at the hospital.
Instead, regional specialist centres will be set up in Blackburn, Carlisle and Preston.
The trust said it was considering a judicial review.
Mr Ollerenshaw, Conservative MP for Lancaster and Fleetwood, said: “This is a huge blow and I am hugely disappointed.
“While I accept that reviews to create fewer but more specialised units for services like vascular treatments are correct in principle, the way the process has been handled in our area has been fundamentally flawed.
“I have raised this matter in the House of Commons directly with the Health Minister and hope our local councils will also make their opposition known.
“If the hospital trust decides to launch a judicial review against this outcome, I will support them in that action.”
Trust chairman Sir David Henshaw said he was “extremely disappointed” with the decision which he called “fatally flawed”.