Which administration route allows for bowel preparation before medical procedures?

The use of an enema as an administration route for bowel preparation before medical procedures is highly effective. An enema involves the introduction of liquid into the rectum and colon via the anus. This method is specifically designed to clear out the bowel, making it suitable for procedures that require a clean colon, such as colonoscopies or certain surgeries. The liquid administered helps to soften stool, stimulate bowel movements, and flush out the contents of the intestines.

While the rectal route is also relevant for certain medications, it is not specifically tailored for bowel preparation like an enema is. The nasal route involves drug administration through the nasal mucosa, which does not pertain to bowel cleansing. Topical administration involves applying medications to the skin or mucous membranes, which is not related to bowel preparation at all. Therefore, the enema is the most appropriate and effective choice for this purpose.