Clinical characteristics of amniotic fluid embolism: an experience of 29 years.

Aim: The aim of this study was to elucidate the clinical characteristics and risk factors for amniotic fluid embolism (AFE).

Methods: We performed a retrospective case study analysis of patients using medical records and autopsy records. The diagnosis of AFE was based on the presence of clinical symptoms using Clark's criteria and autopsy results. We analyzed patient records from a 29-year period in three hospitals affiliated with the Nippon Medical School in Japan.

Results: Ten diagnoses of AFE were found in the records. First, we classified AFE patients into two types based on the initial presenting symptoms: post-partum hemorrhage and cardiopulmonary collapse. Fifty percent of the patients initially presented with post-partum hemorrhage and disseminated intravascular coagulation. Most were diagnosed with post-partum hemorrhage or uterine atony at AFE onset. Similarly, 50% presented with cardiopulmonary arrest or pulmonary arrest as initial symptoms, and most were diagnosed with eclampsia. Second, risk factors for AFE included advanced maternal age, multiparity, increased intrauterine pressure and disruptions of the uterine vasculature. Third, the case fatality rate was 70%. Fourth, squamous cells were observed in maternal central venous blood of five patients.

Conclusion: AFE patients were classified into two types based on presenting signs and symptoms. Knowledge of the various initial symptoms of AFE enables a correct diagnosis.