Human Reproduction Biology

Human Reproduction Biology

Introduction

Disseminated intravascular coagulation (DIC) is a pathologic disruption of the finely-balanced process of hemostasis. Massive activation of the clotting cascade results in widespread thrombosis, which leads to depletion of platelets and coagulation factors and excessive thrombolysis. The end result is multiorgan failure and hemorrhage.

DIC was first described in 1901 as a state of "temporary hemophilia" in two pregnant women; one had a retained fetal demise and the other had a placental abruption. Peripartum hemorrhage is estimated to account for 1 to 5 percent of all cases of DIC in high-resource countries; the frequency is higher in low-resource countries.

Any patient in DIC presents a major management challenge, and this challenge is further complicated when a viable fetus is also present. For example, delaying delivery to transfuse the mother in DIC may not be in the best interest of a fetus with a no reassuring fetal heart rate tracing, whereas performing an emergency cesarean delivery on a mother in DIC may not be in her best interest. Even in the setting of fetal demise, labor and delivery of a woman in DIC carries the potential for catastrophic hemorrhage (Mader, 2006). This topic will focus upon DIC related to pregnancy. Broader discussions of the pathogenesis, clinical manifestations, diagnosis, and treatment of DIC can be also found in the paper.

Discussion & Analysis

Pregnancy Complications that may lead to DIC

The most common pregnancy complications that may lead to DIC are (Levi, 2009):

Abruptio placentae

Severe preeclampsia, eclampsia, or HELLP syndrome

Amniotic fluid embolism

Acute fatty liver of pregnancy

Dead fetus syndrome

Septic abortion

Massive hemorrhage, which may be a consequence of disorders such as placenta previa, uterine rupture, placenta accreta, or postpartum uterine atony.

Intrauterine fetal demise as an inciting event is much less common than in previous decades, given that fetal demise is readily diagnosed by ultrasound examination and most patients elect to terminate the pregnancy shortly thereafter. This avoids development of coagulopathy, which is most common when the demised fetus is retained in utero for at least four weeks. Septic abortion is a complication of unsafe abortion, which is most common in areas lacking providers with the necessary skills to perform abortion or in environments that do not conform to minimal medical standards, or both. In the general population, the most common events that may initiate DIC are sepsis, tissue trauma/destruction, and cancer (Thachil, 2009).

Pathophysiology and Pathogenesis of DIC

During pregnancy, the coagulation system is in an activated state to prevent excessive bleeding peripartum. In addition to systemic changes in coagulation factors, trophoblast cells that line the vascular bed of the placenta strongly express tissue factor, similar to other vascular endothelial cells. In normal coagulation, tissue factor binds to factor VIIa. This complex generates factor Xa, which binds to its cofactor, Va, to convert prothrombin to thrombin. The latter cleaves fibrinogen to fibrin and simultaneously causes platelet aggregation. This sequence is normally tightly regulated by multiple hemostatic mechanisms, including tissue factor pathway inhibitor, antithrombin, and activated protein C (Gerbasi, 1990).

In DIC, however, these physiologic regulatory mechanisms are overwhelmed or ...