He underwent an angioplasty and all the three blockages in his arteries were successfully removed. This test is very important in finding where the blockages are in the arteries. Ash ingestion may also cause gastrointestinal blockages. It may be caused by artery blockages, rupture, mechanical compression, or vasoconstriction. This is commonly done to relieve blockages within the trachea. Engineers tried to alleviate the blockages to no avail. High flow velocities keep the system free of any blockages or sedimentation. Oil can congeal in pipes, provoking blockages. Anastomoses provide critical alternative routes for blood to flow in case of blockages. Any blockages of these freedoms could prevent the satisfaction of the basic needs. Fluoroscopy is used to look for blockages, or other lesions such as stones. In the United States, almost half of all sewer blockages are caused by grease. However, medications will not remove the blockages from the body. With flush toilets, using newspaper as toilet paper is likely to cause blockages. These blockages can lead to cell death.