Post mortem

• Cellular death


  Biological cell ceasing to carry out its functions
• Types of cellular death


  • Apoptosis - Programmed Cell Death
  • Necrobiosis - Physiologic Death
  • Necrosis - Pathological Death
• Necrosis


  • Focal death along with degradation of tissue by hydrolytic enzymes liberated by cells
  • It's invariably accompanied by an inflammatory reaction
  • Cell death due to lethal injury
• Nuclear changes in cell death

  • Karyolysis
  • Pyknosis
  • Karyorrhexis

  
• Cytoplasmic changes in cell death include increased eosinophilia
• Necrosis vs Apoptosis


  • Necrosis: Cell size enlarged (swelling)
  • Apoptosis: Cell size reduced (shrinkage)
  • Necrosis: Nucleus undergoes pyknosis, karyorrhexis, karyolysis
  • Apoptosis: Nucleus fragments into nucleosome-sized fragments
  • Necrosis: Plasma membrane disrupted
  • Apoptosis: Plasma membrane intact, may be released in apoptotic bodies
  • Necrosis: Cellular contents frequently present
  • Apoptosis: Cellular contents no
  • Necrosis: Invariably accompanied by inflammation
  • Apoptosis: Often physiologic means of eliminating unwanted cells, may be pathologic after some forms of cell injury

  
• Types of necrosis


  • Coagulative necrosis
  • Liquefactive necrosis
  • Gangrenous necrosis
  • Caseous necrosis
  • Fat necrosis
  • Fibrinoid necrosis
• Coagulative necrosis


  • Most common type of necrosis caused by irreversible focal injury
  • Less often caused by bacterial and chemical agents
  • Commonly affects the heart, kidney, and spleen
  • In early stage, foci are pale, firm, and slightly swollen
  • With progression, they become more yellowish, softer, and shrunken
  • Results from denaturation of proteins and enzymatic digestion of the cell
• Liquefactive necrosis


  • Commonly due to ischaemic injury and bacterial or fungal infections
  • Degradation of tissue by the action of powerful hydrolytic enzymes
  • Affected area is soft with a liquefied center containing necrotic debris
  • Later a cyst wall is formed
  • Cystic space contains necrotic cell debris and macrophages filled with phagocytosed material
  • Cyst wall formed by proliferating capillaries, inflammatory cells, and gliosis (brain) or proliferating fibroblasts (abscess cavity)
• Gangrenous necrosis


  • Usually coagulative due to ischaemia
  • Characterized by primarily inflammation provoked by virulent bacteria
  • Three types: dry, wet, and gas gangrene
  • Dry gangrene: Affected part is dry, shrunken, and dark black
  • Wet gangrene: Affected part is soft, swollen, putrid, and rotten
  • Gas gangrene: Affected area is swollen, edematous, painful, and crepitant due to gas bubbles within the tissues
• Caseous necrosis


  • Found in the centre of foci of tuberculosis infections
  • Combines features of both coagulative and liquefactive necrosis
  • Resembles dry cheese, soft, granular, and yellowish
  • Necrosed foci are structureless, eosinophilic, and contain granular debris
• Fat necrosis


  • Special form of cell death peculiar to fatty tissue
  • Occurs in acute pancreatic necrosis and traumatic fat necrosis (breast)
  • In pancreas, liberation of pancreatic lipase from injured or inflamed tissue results in necrosis
  • Fat necrosis results in hydrolysis of neutral fat into glycerol and free fatty acid
• Fibrinoid necrosis


  • Characterized by deposition of fibrin-like material with staining properties of fibrin
  • Encountered in various examples of immunologic tissue injury, arterioles in hypertension, peptic ulcer
  • No distinctive gross appearance, identified by brightly eosinophilic, hyaline-like deposition
• Primary changes in somatic death


  • Circulatory failure - immediate death
  • Respiratory failure - absence of oxygen
  • Nervous failure - loss of reflexes
• Secondary changes in somatic death

  • Algor mortis - cooling of the body
  • Rigor mortis - stiffening of the muscles
  • Livor mortis - purplish discoloration of the skin
  • Post-mortem clotting - occurs slowly immediately after death
  • Desiccation - drying and wrinkling of cornea
  • Putrefaction - production of foul-smelling gases, greenish blue discoloration, softening of muscles, retraction of cornea, loss of rigor mortis, peeling of skin with crepitation
  • Autolysis - cell digestion
• Autopsy


  Process of taking pieces of tissue from a dead person to determine, investigate, and preserve the cause of death
• Pre-requisites of autopsy procedure


  • Written consent
  • Type of autopsy to be performed
  • Apparatus or instruments needed
  • Pathologist on duty
• Types of autopsy


  • According to purpose: Routine hospital autopsy, Medico-legal autopsy/forensic/coroner's, Anatomical or academic
  • According to completeness of procedure/technique: Partial, Complete
  • According to manner of incision or opening the cadaver: Y-shaped incision, Straight cut incision
• Other techniques of dissection


  • Rudolf Virchow's - one by one removal of the organs
  • Anton Ghon's - organs removed by block
  • M. Letulle's - organs removed "en masse"
  • Carl Rokitansky's - in situ dissection + en bloc removal
• Common apparatuses or instruments needed during autopsy procedure


  • Bone marrow borer
  • Sterile syringes and needles
  • Spatula
  • Electric saw for bones
  • Culture medium
  • Specimen bottles with fixatives
  • Different sizes and types of forceps
  • Clean dry slide
  • Weighing scale
  • Knives, scissors
  • Alcohol lamp
  • Surgical gloves, surgical masks
• Normal weight of organs

  • Brain - 1300 grams
  • Heart - 300 grams
  • Kidney - 150 grams
  • Liver - 1500 grams
  • Lungs - 550/450 grams
  • Uterus - 50/100 grams
  • Ovary - 10 grams
  • Prostate - 20 grams
  • Pituitary - 0.7 grams
  • Pancreas - 100 grams
  • Spinal cord - 25 grams
  • Spleen - 150 grams