In the mouse, IP injection should proceed only after aspiration has shown that the needle is properly positioned.

In the mouse, IP injection should proceed only after aspiration has shown that the needle is properly positioned.

• A. True
• B. False
• C. Only after intravenous confirmation
• D. Never aspirate before IP injection

Answer: (A)

Guiding principle: verify needle placement before delivering the substance. For intraperitoneal injections in mice, you aspirate after inserting the needle to check that you’re not in a blood vessel. If blood is drawn, you’ve likely hit a vessel and must reposition and re-aspirate. Only when the aspirate shows no blood do you proceed to inject into the peritoneal cavity. This reduces the risk of delivering the drug systemically or puncturing organs. Aspiration is the safeguard that ensures you’re in the intended space, not a vessel.

Guiding principle: verify needle placement before delivering the substance. For intraperitoneal injections in mice, you aspirate after inserting the needle to check that you’re not in a blood vessel. If blood is drawn, you’ve likely hit a vessel and must reposition and re-aspirate. Only when the aspirate shows no blood do you proceed to inject into the peritoneal cavity. This reduces the risk of delivering the drug systemically or puncturing organs. Aspiration is the safeguard that ensures you’re in the intended space, not a vessel.