What type of enema injects an oil held in the rectum to soften the stool?

A retention enema is specifically designed to introduce a liquid, such as oil, into the rectum and hold it there for an extended period. This type of enema is beneficial for softening stools and making bowel movements easier, especially in patients with constipation or impacted stools. The oil in the retention enema works by lubricating the stool and the intestinal lining, facilitating easier passage during a bowel movement.

In contrast, other types of enemas serve different purposes. Emulsifying enemas typically involve a mixture aimed at breaking down emulsions, while suspending enemas are designed to hold particles in suspension for therapeutic purposes. Cleansing enemas, on the other hand, focus on flushing the intestines to relieve constipation or prepare for medical procedures. Thus, the retention enema's specific function in softening and retaining oil in the rectum makes it the correct choice.