Is operation the only alternative for deep vein thrombosis with pulmonary embolism?

No. In fact, surgery is almost never indicated for pulmonary embolism or dvt. Almost all cases can be treated effectively with blood thinners.
Almost never. As dr. Hermann said, surgery is virtually never recommended as treatment for a pulmonary embolism. Blood thinners are generally always the treatment of choice.
No. Most cases are treated with blood thinners but more severe cases might need endovascular treatment such as a catheter and drugs to help break down the clot directly, a balloon to open narrowed veins or stents to keep them open. All are done as outpatient procedures usually. We sedate patients and use local numbing medicine.