The bruising of the glans after circumcision is mostly caused by bleeding from the surgical wound, which seeps into the submucosa of the glans to form a haematoma.
A small amount of bleeding should be stopped by pressure bandaging and keeping the vulva clean, and the haematoma can gradually absorb and heal.
For larger haematomas, a second operation should be given to remove the accumulated blood, haemostasis of the wound and prevent infection treatment.