Administration of autologous fetal membranes: Effects on the coagulation in pregnant mini-pigs.

OBJECTIVE

A hallmark of the so-called amniotic fluid embolism is the induction of coagulation defects. Entry of meconium-free autologous amniotic fluid into the circulation, however, is innocuous. Little is known about the true causative agent or agents. The purpose of this study was to assess the effects of homogenized autologous fetal membranes (FM) on the coagulation system in the mini-pig model.

DESIGN

Laboratory study.

SETTING

University institute animal laboratory. SUBJECTS: Six near-term pregnant, Göttingen-bred mini-pigs. INTERVENTIONS: After induction of general anesthesia, FM were col-lected from all animals by cesarean section. Animals received 2 g FM (shredded and suspended in lactated Ringer's solution) via an ear vein. MEASUREMENTS: Blood samples were taken from a central vein before administration (baseline), immediately after administration, every 10 mins until 90 mins after administration, and every 20 mins until 150 mins after administration. The following parameters were measured: platelets, partial thromboplastin time, prothrombin time index, fibrinogen, factors II, V, VII, VIII, IX, X, XI, antithrombin III, and protein C. The values relative to baseline in the FM group were compared with a historical control group by rank order test. A p <.05 was considered significant. MAIN

RESULTS

In the FM group (compared with the control group), platelets were lower; partial thromboplastin time was prolonged; fibrinogen was lower; prothrombin time index was lower (ie, prothrombin time was prolonged); protein C and antithrombin III were lower; and activity levels of factors V and VII were lower. The levels of factors II, VIII, IX, X, and XI showed a trend toward lower activity in the FM group, but the differences were not statistically significant.

CONCLUSIONS

FM can activate coagulation in mini-pigs. The laboratory parameter changes seen are typical for disseminated intravascular coagulation. However, the full clinical picture of amniotic fluid embolism and disseminated intravascular coagulation could not be elicited despite the high dose of FM used.