Maternal death analysis from the Japanese autopsy registry for recent 16 years: significance of amniotic fluid embolism

AIM: To clarify the cause of maternal deaths, an autopsy is essential. However, there has been no systemic analysis of maternal death in Japan based on autopsy cases. MATERIAL & METHODS: Maternal death reports were retrieved from a large amount of registered autopsy data on maternal death in the series of 'Annual of pathological autopsy cases in Japan'. These files contain 468,015 autopsy records from 1989 to 2004. We collected 193 cases of maternal death due to direct obstetric causes. We recorded all the data into Excel files. Then we analyzed the causes of death and classified them into 11 categories. RESULTS: The causes of maternal death were as follows: amniotic fluid embolism (AFE), 24.3%; disseminated intravascular coagulation (DIC) related to pregnancy-induced hypertension, 21.2%; pulmonary thromboembolism, 13.0%; injury to the birth canal, 11.4%; medical and surgical complications, 9.8%; and atonic bleeding or DIC of unknown cause, 8.3%. A discrepancy between the clinical diagnosis and pathological diagnosis was frequently observed in cases of AFE, septic DIC and injury to the birth canal. AFE diagnosed by autopsy was often clinically diagnosed as atonic bleeding or DIC of unknown cause before death. Half of the cases of AFE diagnosed by autopsy were associated with DIC. CONCLUSION: We found that AFE, DIC related to pregnancy-induced hypertension, pulmonary thromboembolism and injury to the birth canal were the major causes of maternal death in Japan. AFE had various clinical features such as uterine atony and DIC in addition to pulmonary cardiac collapse.