The symptoms depend on the location and cause of the gangrene. If the affected area involves the skin or is close to the skin, the symptoms may include:

• Discoloration (blue or black if skin is affected; red or bronze if the affected area is beneath the skin)
• Loss of sensation (which may occur after severe pain in the area)
• Foul-smelling discharge

If the affected area is internal (such as gangrene of the gallbladder or gas gangrene), the symptoms may include:

• Persistent or severe pain
• Fever
• Gas in tissues beneath the skin
• General ill feeling
• Septic shock

• Blood tests -- a CBC may show a high white blood cell (WBC) count
• X-rays
• CT scan for internal conditions, such as abdominal pain
• Surgical exploration to confirm (and treat) gangrene
• Microscopic examination of tissue to look for cell death
• Tissue or fluid culture from wounds to identify bacterial infection
• An arteriogram to help plan treatment for vascular disease