Which site is least appropriate for an intramuscular injection?

The subdeltoid site is the least appropriate for an intramuscular injection primarily due to its anatomical location and the risk of injury to surrounding structures. The deltoid muscle, where this site is located, is smaller compared to other muscle sites recommended for intramuscular injections, such as the vastus lateralis or rectus femoris. This smaller volume capacity makes it less ideal for larger doses of medication.

Furthermore, the subdeltoid area is in close proximity to the radial nerve and the axillary nerve, which increases the risk of nerve damage during injection. On the other hand, the vastus lateralis, dorsogluteal, and rectus femoris are larger muscle groups that can accommodate larger volumes and have lower risks associated with injecting substances into them. The dorsogluteal site, while historically common, has become less favored due to the proximity to the sciatic nerve, yet it still remains a larger muscle site compared to the deltoid.

In summary, the subdeltoid is less appropriate due to its limited capacity and the higher risk of complications related to nearby nerves, making it less favorable compared to other recommended sites for intramuscular injections.