The risk of hematoma is most commonly associated with which injection?

• A. Posterior superior alveolar injection
• B. Inferior alveolar nerve block
• C. Incisive nerve block
• D. Infraorbital injection

Answer: (A)

Hematoma forms when a blood vessel is injured during the injection, so the area with the richest venous network near the injection site carries the greatest risk. The posterior superior alveolar region sits next to the pterygoid venous plexus in the infratemporal space, where large veins are easily breached by the needle. That proximity makes a PSA block the most likely to produce a hematoma, with bleeding that can spread into the cheek or maxillary sinus.

The other injections occur in areas with fewer large vessels or along a path that is less likely to hit significant veins, so the chance of hematoma is lower.