Why should an IP injection be made on the mouse's right side?

• A. It avoids puncturing cecum
• B. It reduces stress
• C. It is faster
• D. It avoids hitting the liver

Answer: (A)

Intraperitoneal injections in mice are positioned lower on the abdomen to minimize injury to internal organs. The cecum is a large, easily punctured part of the gut that sits in the lower abdomen, and approaching from the right side keeps the needle away from it. Puncturing the cecum can release intestinal contents into the peritoneal cavity, causing inflammation or infection and compromising the procedure as well as the study. So, choosing the right-side lower quadrant makes the injection safer by reducing the risk of hitting the cecum. The other ideas listed don’t directly address this particular injury risk, which is why this site is preferred.