Antemortem blisters are mostly produced during burns.
Features of antemortem blisters:
- surrounded by an area of hyperemeia
- floor is reddened with swelling of papillae
Postmortem blisters (blisters of putrefaction) are formed 18-24 hours after death due to putrefaction and production of gases which force blood, air to liquid fat into the superfical layers of skin forming blisters. They are found first in the lower surface trunk and thighs where there is more fluid collection due to hypostatic edema.
Features of postmortem blisters:
- no surrounding hyperemeia
- floor is not reddened