Answer by  
                                                                                          mammakat (11147)
                                                            
                          
                          
                                                          Most commonly this refers to clots forming in the veins (usually leg), which can be dangerous as they can break off, migrate to the lungs, causing a pulmonary thrombosis or embolism, blocking a vein. this can cause a stroke. This condition needs to be taken seriously and requires medical attention.