Jobst compression stockings (or other brands) are used to decrease venous blood congestion or pooling while a patient is immobile on the operating table, in order to reduce blood clot formation. Sequential compression devices actively "pump" the blood in your lower extremities, and have been shown by numerous studies to be an even better way to decrease blood clots after surgery. Compression stockings are simply one way to decrease risks (better than doing nothing), but "necessary?" No. Neither is it "necessary" for your surgeon to be well-rested and attentive--s/he has probably done this operation hundreds of times and can probably do it blindfolded. Of course, neither is "right" nor proper.
But the second word that I take issue with is "prevent." Use of antibiotics won't "prevent" infection, they only reduce the risk of an infection. Similarly, use of compression stockings, or even sequential active compression devices, or even injectable blood thinners do not "prevent" blood clots, they only reduce the risk!
But why would you fail to do anything that might enhance your safety, reduce your risks, or potentially save your life?
If you are asking because your surgeon didn't mention this, perhaps it's because it's already a routine where your surgeon operates and every patient automatically gets them, just as in our office surgical facility (we also use active sequential compression devices for every case, not just certain ones).
If there is any question, please ask at the time of surgery or beforehand. Best wishes and good luck! Dr. Tholen