Does this look like necrosis? And what treatment will prevent it worsening? (Photo)

Thank you for your question as well as photos.  Delayed healing can happen with any type of surgery.  I would recommend following closely with your surgeon to ensure complete healing.  Best wishes!

You need to see your surgeon right away.  While you do not have a large blatant necrosis, you do have evidence of a process that should examined.  Hopefully all is well.

Judging from your photos, it appears that you do have some distinct areas of skin slough (necrosis), primarily on the left. Most likely, this will not get worse but improve under close supervision and appropriate management by your surgeon.

Thank you for your pictures.  It does look like you have some small areas of superficial skin loss.  Topical antibiotics (Silvadine cream) can be helpful but the areas just have to heal naturally. Revision may or may not be advisable.Dr. ES

It is a small area, and looks fairly superficial so should heal well.  Keep it moist with Vaseline so you don't get contraction of the area.  If you get some scarring - which should be minimal anyway - you can do some laser at about 6-8 weeks to eliminate the scar.  The right side looks more like some residual scabbing. And the darker color is probably deep bruising.