\-A deep vein is occluded by a thrombus (example: blood clot), causing inflammation, blocked venous return, cyanosis, and edema.
\-Cause may be prolonged bed rest, history of varicose veins, trauma, infection, cancer, obesity, immobility, heart failure, or the use of estrogen hormones.
\- S: Sudden onset of intense, sharp, deep muscle pain.
O: Increased warmth; swelling; redness; dependent cyanosis is mild or may be absent; tender to palpation