Pathology



Pathology

Lecture 23 Traumatic Injuries, Asphyxia & Drowning

1) To develop a basic understanding of the various types and terminology of blunt, sharp, penetrating and asphyxial injury.

a. Blunt injury – resulting from contact with an object having flat or rounded surfaces. Categorized as abrasion (scrape), contusion (bruise), and laceration from tissue tearing. Blunt force trauma to the head may result in extracerebral hematomas: epidural hematoma, subdural hematoma, or subarachnoid hemorrhage. Cerebral contusions can present in several forms depending on the type of impact: coup (a blow), contre-coup (a fall), fracture, or herniation.

b. Sharp injury – stab wounds have greater depth than width. Examining the skin can tell if the weapon moved, its quality (single/double edged, serrated), and identify marginal contusions (guard, handle, hand). Internal appearance can be deeper than the length of the weapon. Incised wounds have greater width than depth, are not usually fatal, and may be confused with laceration although no contusions are usually present.

c. Penetrating injury – gunshot wounds vary in severity depending on the type of gun/bullet and the wound area. The kinetic energy of the bullet is related to its mass and velocity (KE = ½ MV2). Range of fire leaves characteristic patterns: point blank range causes skin charring with soot and gunpowder deposition, intermediate range produces stippling and may leave soot, and distant ranges cannot be determined. Entrance wounds have marginal abrasions and may have an irregular contour (ricochet) while exit wounds have a variety of shapes and no marginal abrasions unless skin was in contact with an object (shored). Shot gun wounds have more dispersed stippling and the wad may enter the body in a contact wound, no exit wound is usually present.

d. Asphyxial injury – an external condition or substance deprives the body tissues of oxygen with no pathognomonic signs. Categories of suffocation include: entrapment, smothering, choking, mechanical, suffocating gases and strangulation (also hanging). Drowning results in asphyxia from submersion in a liquid and is the second most common type of non-intentional injury for the 5-44 year old age group. Accidents are the most common, followed by suicide and homicide.

2) To make clinicopathological correlations in cases of fatal disease and injury. Determine mechanism of death, take history and evidence into consideration, and differentiate the cause between a disease state and injury.

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