Should Bruising from Lipo Still Be Around 4 1/2 Months Later?

Yes, unresolved bruising 4 months after liposuction would be unusual if not impossible. Most bruising resolves after about 1-2 weeks. Most likely you have dealing with some staining of the skin, possibly from hemosiderin (a byproduct of broken down blood cells). The body should eventually resolve this for you, but it could take months to years. I am not certain how well hydroquinone works for this. In general, hydroquinone is thought to affect the melanocytes in the skin, which really doesn't have anything to do with hemosiderin deposits. But, a dermatologists recommendations should be followed instead of mine for this. 

   Hemosiderin staining can improve over about one year's time.  Kenneth Hughes, MD Los Angeles, CA

This type of skin discoloration can occur with liposuction, it will fade over time and follwing your PS instructions of using hydroquinone to treat those areas is the best route. Be sure to continue to massage the area and do not expose the area to any sun as it can make the situation worse. Good luck and the discoloration will fade with time.