Degree and Direction of Force and Cause of Death

Generally, multiple, extensive, and open cutaneous injuries imply a greater degree of force. Injuries distributed on different surfaces of the body may, depending on the circumstances of injury, represent multiple concurrent impacts or repetitive trauma. A cutaneous injury is an external sign of severe visceral injury and indicates significant absorption of energy at that site. Rarely, fatal exsanguination is caused by a skin laceration (Fig. 7). Extensive soft tissue trauma can be a cause of death (see Subheading 12.1. and refs. 3 and 14).

The degree of bruising reflects the amount of inflicted trauma, but a number of factors modify this interpretation (13).

Contusions can be extensive yet arise from minimal trauma. If an individual is taking medications (e.g., aspirin, anticoagulants) or has a bleeding diathesis (e.g., cirrhosis, hemophilia), then there is a predisposition to hemorrhage (see Subheading 3.4.1.1.; Fig. 7; and refs. 8 and 13). Children bruise more easily because of their loose, delicate skin (8,13). Elderly individuals, because of dermal atrophy and decreased capillary support,

Fig. 7. Alcoholic found dead in home. Acute ethanol intoxication (240 mg/dL). Cirrhosis seen at autopsy. (A) Evidence of considerable bleeding at scene. (B) Exsanguination from laceration on left eyebrow. Hematoma, upper eyelid.

develop senile ecchymoses (8,13,15). These bruises typically arise in individuals more than 60 yr of age and arouse suspicion of abuse (15). Senile ecchymoses are characterized by nonpalpable foci of hemorrhage with irregular edges. They typically involve the arms and to a lesser extent, the sides of the neck, and legs (Fig. 8). They are seen in nursing home patients, but they also occur in individuals in acute care hospitals and at home. Minimal trauma, such as lifting or other means of physical support, can precipitate ecchymoses. Obesity enhances bruising (8,13).

The nature of the impacted site influences the skin injuries seen. Force inflicted over a bony prominence (e.g., orbital ridge) is more likely to cause laceration (Fig. 7).

Unlike abrasions and lacerations, contusions do not always indicate a direct impact site because of tracking of blood (Fig. 9). Direction of force can be determined in abrasions and lacerations (e.g., abraded layers of skin pushed to one side, unequal undermining of a laceration consistent with tangential force [3]). If extravasated blood collects in deep soft tissue (hematoma), bruising is not apparent initially and is appreciated only by incision of the suspected injured site (Fig. 10; refs. 3 and 8). The scalp is a site of "hidden" bruises (Fig. 11). Scalp hair covers contusions. A scalp contusion may not be appreciated externally until the scalp is reflected. Hemorrhage is typically seen at the scalp-skull interface, which shifts with blunt impact. If the individual survives, blood may reach the skin surface, and the consequent bruise can appear more recent. The extent of bleeding is increased if the injured tissue is loose, vascular, or both (e.g., periorbital, genital areas; see Fig. 7 and refs. 3, 8, and 13). Continued pressure on an injured site reduces bleeding (8).

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