Coagulation Factor Changes Associated With Postpartum Hysterectomies

Overview

The purpose of this study is to examine components of the coagulation system in women undergoing postpartum hysterectomy and to compare laboratory parameters of coagulation in these women to women at increased risk for a postpartum hysterectomy, but who do not have postpartum hemorrhage and a postpartum hysterectomy. During normal pregnancy, the hemostatic balance tips toward hypercoagulation. Non-obstetric surgical blood loss is associated with increased coagulation activity. We have observed that women undergoing a postpartum hysterectomy become hypocoagulable secondary to a consumptive coagulopathy and/or excessive fibrinolysis. This coagulopathy may lead to the administration of multiple blood products. Worldwide, postpartum hemorrhage is a leading cause of maternal death. Plasma levels of tissue plasminogen activator, urokinase plasminogen activator and their inhibitors increase during pregnancy. During labor and delivery activation of coagulation occurs with consumption of platelets, coagulation factors and inhibitors. Obstetric complications during delivery can excessively activate the coagulation system and disseminated intravascular coagulation may ensue. Current treatment for postpartum coagulopathy is non-specific and primarily consists of replacing blood components. If specific causes or markers of abnormal coagulation can be identified in women at risk, then it might be possible to target (with specific medications) specific abnormalities early in the process and decrease hemorrhage and the need for blood transfusions.

All women scheduled for a Cesarean-hysterectomy will be asked to enroll in the study, as well as the women with the following diagnoses, which puts them at increased risk for Cesarean hysterectomy: placenta previa, placenta accreta, vaginal trial of labor after a previous Cesarean delivery. Written, informed consent will be obtained from all subjects. A blood sample will be obtained shortly after admission to the hospital. In women who go on to have a hysterectomy, blood samples will be obtained at predefined time periods (at time of decision to perform hysterectomy, with every clinically indicated blood draw for coagulation tests, 2 hours after delivery. The next patient at risk of Cesarean hysterectomy, but who does not go on to have a hysterectomy, will serve as a cohort control. Blood samples will be drawn at 2 hours after delivery for coagulation testing. Baseline samples from all other study subjects will be discarded and no further blood work will be obtained. The primary outcome will be the the level of fibrinogen at 2 hours following delivery as a marker of consumptive coagulopathy. Every patient at risk for hemorrhage has at least one peripheral intravenous cannula inserted upon admission to the Labor \& Delivery Unit. A 2nd IV cannula is almost always placed, usually when the decision is made to proceed with a Cesarean delivery. All study subjects will have a 2nd IV cannula placed for drawing blood for study coagulation tests, and any other clinically indicated blood tests. The cannula will be connected to a stopcock with a "heparin lock" (cannula and stopcock are flushed with saline between aspirations) and left in place for 48 hours after delivery.