Postmortem Changes

Classification

1. Pallor Mortis (Immediate)

• Occurs within 15-30 minutes of death
• Skin becomes pale due to loss of capillary circulation and cessation of blood flow
• Most noticeable in fair-skinned individuals
• Accompanied by primary relaxation - all muscles go flaccid immediately after death (sphincters relax, bowel/bladder may empty)

2. Algor Mortis (Cooling of the Body)

• Body temperature falls toward ambient temperature after death
• Rate of cooling: approximately 1-1.5°C per hour under average conditions (the "Rule of thumb")
• Henssge nomogram is used forensically to calculate PMI from body and ambient temperature
• Factors that accelerate cooling: thin build, wet clothing, cold/windy environment, youth
• Factors that delay cooling: obesity, warm environment, clothed body, fever before death

3. Livor Mortis (Postmortem Hypostasis / Cadaveric Lividity)

• Indicates the posture at the time of death
• Shifting vs. fixed lividity helps estimate PMI
• Unusual distribution indicates body was moved
• Must be distinguished from bruising: lividity blanches on pressure (until fixed) and does not cross natural skin creases
• Essentials of Forensic Medicine and Toxicology, 36th ed., p. 161-163
• Parikh's Textbook of Medical Jurisprudence, p. 181-183

4. Rigor Mortis

• Cadaveric Spasm (Instantaneous Rigor): Occurs at the moment of death following violent exertion, convulsions, or extreme hyperthermia. The muscle stiffens instantaneously without primary relaxation. An object held at death (e.g., weapon) is found firmly clenched. This has major medicolegal significance as it cannot be simulated postmortem.
• Goose skin (Cutis anserina): Erector pilae muscles affected by rigor mortis produce puckered, granular skin - also seen in drowning (cold water).
• Breaking rigor: Rigor can be broken by mechanical passive stretching. Once broken, it will NOT return. This can mislead PMI estimation if rigor is broken during body handling.
• Heat stiffening: Distinct from rigor mortis - occurs in burn victims. Muscles contract and coagulate from heat, producing characteristic "pugilistic attitude" (boxer's posture) with flexed elbows, knees, and clenched fists.

• DiMaio's Forensic Pathology, 3rd Ed., p. 34-35
• Parikh's Textbook, p. 181

5. Late Postmortem Changes

A. Putrefaction (Decomposition)

1. Greenish discoloration of the right iliac fossa (caecum area) appears first, around 24-48 hours in warm conditions - due to formation of sulfhaemoglobin from hydrogen sulfide reacting with hemoglobin
2. Color spreads across the abdomen and chest
3. Marbling - network of discolored blood vessels visible through skin, due to bacterial gas in vessels carrying sulphhaemoglobin
4. Bloat - gas accumulates in intestines and body cavities (abdomen distends)
5. Skin slippage - epidermis separates from dermis; blister formation
6. Purging of bloody, malodorous fluid from nose and mouth (often mistaken for ante-mortem hemorrhage)
7. Tissues liquefy and organs disintegrate
8. Skeletonization - soft tissue completely lost

• Forensic Anthropology: A Comprehensive Introduction, 2nd Ed., p. 297-300

• High temperature, high humidity: accelerate
• Immersion in water, burial, cold: slow
• Septicemia/fever before death: accelerates
• Antiseptic substances ingested: delays

B. Adipocere Formation

• Conversion of body fat into a waxy, soap-like substance (saponification)
• Hydrogenation of unsaturated fatty acids + hydrolysis of triglycerides → hydroxy fatty acids (adipocere)
• Conditions: warm, moist, anaerobic environment (waterlogged bodies, buried remains)
• More common in obese individuals, women, and infants
• Can persist for centuries - important in identification of old remains
• Body contours are preserved, which aids in estimating PMI and identifying injuries

C. Mummification

• Desiccation and drying of body tissues
• Conditions: hot, dry, well-ventilated environment (desert, hanging bodies in airflow)
• Begins with face, hands, and feet - brown to golden-brown discoloration and wrinkling
• Natural or deliberate; skin becomes leathery and hard
• Preserves features and may preserve injuries

D. Maceration

• Softening and disintegration of tissues in a sterile fluid environment (e.g., a retained fetus in utero after intrauterine death)
• Skin becomes red and peeling; body is soft and friable

Decomposition Stages (Summary Table)

• Forensic Anthropology: A Comprehensive Introduction, 2nd Ed., p. 300

Medicolegal Importance

1. PMI estimation - algor + livor + rigor mortis together help narrow the time of death window
2. Position of body - livor mortis indicates original posture; unusual distribution suggests body was moved
3. Cadaveric spasm - indicates the last act of the deceased (suicidal vs. homicidal weapon grip)
4. Distinguishing antemortem injury from postmortem artifact - vital reaction (inflammatory response, active bleeding) confirms antemortem injury; lividity and postmortem changes may mimic bruising
5. Decomposition pattern - used by forensic anthropologists for PMI when early changes are no longer present