Amniotic fluid embolism
This section of lung is from a woman who died in shock shortly after delivery. The stains are H&E on the left and Twort stain on the right. Within the vessels are squames from the fetus which were present in amniotic fluid. A DIC syndrome is often triggered by the release of thrombogenic substances.
Amniotic fluid containing fetal squamous cells, lanugo and other debris can enter the maternal circulation during labor or during or shortly after vaginal or cesarean delivery or dilation and evacuation.. Current thinking is that the resultant clinical disaster is not due to obstruction as in embolization of blood clots but due to the triggering of pulmonary vasospasm and disseminated intravascular coagulation. Complement activation may play an important role. Clinically, the patient becomes acutely dyspneic and hypotensive. Massive hemorrhage may follow and most patients expire quickly.