PO stands for which phrase?

• A. By mouth
• B. Nothing by mouth
• C. Postoperative
• D. Per os

Answer: (A)

PO is a route indicator meaning administration by mouth. In everyday nursing practice, when you see an order or MAR note PO, it tells you to give the medication orally—swallowed or taken in the mouth. The Latin origin is per os, but the common English expression used on orders is by mouth, which is why this option is the best fit for the question. It’s important to distinguish this from nothing by mouth (NPO), which means no intake of food or liquids, and from terms like postoperative, which refer to the period after surgery. Per os is technically the Latin form of the same idea, but in standard nursing notation the English phrase “by mouth” is the expected answer here.