T-MALE Injection Update:
The CDC update regarding aspiration before IM injection:
Aspiration Before Injection
Previous versions of the General Recommendations have recommended aspiration (i.e., gently pulling back on the plunger to check for blood before injection) prior to injection, particularly before intramuscular injection. No data exist to document the necessity of this procedure. The 2002 General Recommendations on Immunization does not recommend aspiration before injection.
Though this was written in regards to immunizations, it also applies to general IM injections. It is still up to you if you wish to check for blood but it's not necessary according to the CDC (Center for Disease Control & Prevention) It's never hurts to be sure but be gentle when you do, if you continue to aspirate before injecting.
(I was alerted to this by a nurse who used to give me my testosterone injections)