SF 6 is used as a contrast agent for ultrasound imaging. Sulfur hexafluoride microbubbles are administered in solution through injection into a peripheral vein. These microbubbles enhance the visibility of blood vessels to ultrasound.F 6 is used as a contrast agent for ultrasound imaging. Sulfur hexafluoride microbubbles are administered in solution through injection into a peripheral vein. These microbubbles enhance the visibility of blood vessels to ultrasound.
Once constipation (no bowel movement) has gone on for some time, the result can be what is known as an impacted bowel (sometimes called fecal impaction). Essentially, this means that a large lump of dry, hard stool is stuck inside your rectum.
1 In a healthy system, there should be a bowel movement shortly after every meal. 2  As for how long a person can go without a bowel movement and when this becomes life-threatening, that I do not know. In a healthy system, there should be a bowel movement shortly after every meal. 2  As for how long a person can go without a bowel movement and when this becomes life-threatening, that I do not know.