Petechial hemorrhage
Petechial hemorrhage refers to small, pinpoint red marks that appear on the skin or mucous membranes due to bleeding from capillaries. These marks are often significant in forensic pathology, as their presence can indicate causes of death related to asphyxiation, such as strangulation or smothering. The phenomenon occurs when increased pressure within blood vessels leads to their rupture, allowing blood to seep into surrounding tissues. Historically recognized since 1949, petechial hemorrhages can also arise from various medical conditions, including blood disorders characterized by low platelet counts or clotting abnormalities.
In specific scenarios, such as crush asphyxia, the identification of petechial hemorrhages can provide crucial diagnostic information, particularly when they are observed in areas unaffected by tight clothing, a phenomenon known as the "brassiere sign." Additionally, petechial hemorrhages may manifest in non-asphyxiation-related traumas, such as shaken baby syndrome or as a consequence of cardiopulmonary resuscitation (CPR). Their diverse associations highlight the importance of understanding the underlying causes and implications of this condition in both medical and forensic contexts.
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Petechial hemorrhage
DEFINITION: Bleeding from the capillaries into the skin or mucous membranes, which results in tiny (pinpoint) red marks.
SIGNIFICANCE: The presence of petechial hemorrhages can help forensic pathologists determine the cause of death in many cases because such hemorrhages are often an indication of strangulation, hanging, or smothering.
Petechial hemorrhages, sometimes referred to as punctate hemorrhages, have been recognized for years as indicators of the increased pressure on the blood vessels in the head that occurs when the airway is obstructed. They have also been found to occur in many disorders and diseases that involve blood dyscrasias (abnormalities). The mechanism by which petechial hemorrhages occur was first delineated by J. G. Humble in 1949. Anything that leads to increased pressure within the capillaries can cause them to rupture, allowing blood to leak out into the skin or mucous membranes. Petechial hemorrhages are thus caused by tears in the blood vessels and fall into the category known as rhexis hemorrhages.
Forensic pathologists have long recognized the connection between petechial hemorrhages and asphyxiation. A pathologist will often make a diagnosis of “crush asphyxia” when findings include a history of traumatic compression of the chest or abdomen, swelling of the blood vessels due to overfilling (vascular engorgement), and the presence of petechial hemorrhages. It has been shown that if vascular congestion is not present (or possible), then petechial hemorrhages will not form at the site of the compression. Typically, no petechiae are found in areas underneath tight clothes, such as women’s bras. The compression of the skin caused by a bra does not allow for vascular engorgement, so no petechial hemorrhages are found in this region. This “brassiere sign” (petechial hemorrhages over the upper chest with none in the area of the bra) is taken as an indicator of crush asphyxia.
Although petechial hemorrhages are often indicators of asphyxiation, particularly when they are present in the conjunctiva of the eye or on the face, they also occur in a wide variety of other conditions. Trauma that does not involve asphyxiation may also lead to petechial hemorrhage. In the case of shaken baby syndrome, the pinpoint red marks may be found on the retina or conjunctiva of the eye, as well as on the earlobe. Low platelet counts (thrombocytopenia) or coagulopathies (defects in the body’s blood-clotting mechanism) often lead to the existence of petechial hemorrhages, especially on the lower extremities. They are also seen as aftereffects of cardiopulmonary resuscitation (CPR). If CPR successfully restores blood flow to small blood vessels damaged by hypoxia, the vessels may easily rupture, resulting in petechial hemorrhages.
Bibliography
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Sullivan, Debra. "What Causes Petechiae?" Healthline, 25 Aug. 2023, www.healthline.com/health/petechiae. Accessed 19 Aug. 2024.