Effects of postmortem positional changes on conjunctival petechiae

The present study aimed to determine whether postmortem period, physical constitution, cause of death, and cardiopulmonary resuscitation are associated with positional changes in the postmortem appearance of conjunctival petechiae. We retrospectively investigated serial forensic autopsies from 6 h to 6 days postmortem (n = 442; male, 303; female, 139; median age, 62 years; range, 0–100 years). The causes of death were sharp instrument injury, blunt force trauma, fire, intoxication, asphyxia, drowning, hypothermia, hyperthermia, acute heart failure, and natural causes. Of these, 28 (male, n = 18; female, n = 10) were aged ≤5 years. Palpebral conjunctival petechiae were initially assessed at autopsy in supine bodies, then reassessed in prone bodies after 30 min. Among 414 bodies, 291 (70.2%) and 123 (29.7%) who were aged between 6 and 100 years, and 18 (64.2%) and 10 (35.7%) aged <5 years at the time of death, were discovered in the supine and prone positions, respectively. The amounts of petechiae increased within 1.5 days postmortem, but not in those discovered in the prone position. The rates at which petechiae increased were higher in supine overweight bodies (BMI ≥ 25.0) and in those who were discovered supine and had died of asphyxia or drowning (37.5%). Cardiopulmonary resuscitation for bodies discovered in the supine and prone positions did not statistically affect the occurrence of petechiae. Several postmortem factors can cause hypostatic blood redistribution that manifests as increased amounts of petechiae in the palpebral conjunctivae.