Patient Information Resource:
Benign Hematologic (Blood) DisordersA collaborative project of the Arizona Telemedicine Program, the Arizona Health Sciences Library and the Arizona Cancer Center.
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Fibrin Clot Formation Abnormalities
When a wound occurs, several changes take place to minimize blood loss. First, the blood vessel slows the flow of blood past the wound site. Next, platelets collect at the wound site to form a plug. Finally, fibrin clots form scabs to replace these temporary platelet plugs. Fibrin clot formation is dependent on adequate function of clotting factors. Multiple factors can prevent fibrin clot formation.
A. Coagulation Factor Abnormalities
Hepatocellular Disease. In patients with severe liver disease, such as hepatocellular carcinomas and adenomas, insufficient clotting factors may be available to control bleeding. Treatment involves transfusion and antifibrolytic medications such as e-aminocaproic acid (Amicar) and tranexamic acid. Please see Liver Cancer.
Medications. Medications that can affect clot formation include heparin and warfarin (Coumadin). Although both heparin and warfarin are used to prevent thrombosis (the formation of blood clots in the blood vessels), bleeding is an uncommon but possible side effect. Risk factors for heparin-induced bleeding include recent surgery, cardiopulmonary resuscitation (CPR), intracranial hemorrhage, stroke; active peptic ulcer disease; high blood pressure; history of bleeding diathesis; elevated serum creatinine (a blood protein); and age (women > 60, men > 70). Risk factors for warfarin-induced bleeding include use of multiple drugs and coexisting serious illness such as kidney failure or congestive heart failure. When severe heparin-induced bleeding occurs, protamine sulfate may be used to counteract the bleeding tendency. Similarly in the presence of warfarin therapy, bleeding may be treated with vitamin K supplements or transfusions.
Fibrinolytic Therapy. Fibrinolytic, or thrombolytic, agents are used to break up clots. The risk for fibrinolytic-induced bleeding is much higher than it is for heparin or warfarin (Coumadin). Bleeding depends on the dose, length of therapy, and the individual patient. The most serious bleeding threat is intracranial hemorrhage (bleeding within the skull), a rare but usually fatal complication. Bleeding requires immediate treatment, often with cryoprecipitate, platelets, or antifibrinolytic drugs.
B. Disseminated Intravascular Coagulation
In disseminated intravascular coagulation (DIC), both bleeding and clotting occur at the same time. DIC occurs often in cancer patients (it is especially common with prostate cancer). DIC can result from burns, surgery, cancer, injury, or toxins or foreign substances in the blood (such as bacteria). Hematological symptoms arise due to bleeding or clotting in the specific organ affected. These include difficulty breathing, unconsciousness and confusion, swelling in the limbs, bruising, petechiae, purpura, blood in the urine and stool, and bleeding of wounds. The disorder is diagnosed based on patient history, physical examination, and laboratory testing. Although it often exists as a low-grade problem, it can quickly result in death. If bleeding or clotting become serious, they must be immediately treated with blood transfusions and antifibrolytic medications such as heparin or e-aminocaproic acid (Amicar). If possible, the underlying disease should be treated aggressively.
C. Massive Blood Transfusion
When several blood transfusions have been administered, the fibrin in the blood may become too dilute. Bleeding occurs because there is not enough fibrin for the amount of blood in the body. Platelet transfusions may be used to improve clotting function. Another cause of bleeding following red cell transfusion is elevated levels of citrate anticoagulant. Accumulation of citrate anticoagulant, which is added to transfused blood, decreases fibrin’s clotting ability. In patients at risk, blood with low levels of citrate is used for transfusion.
D. Snake and Spider Bites
Some snake and insect bites contain toxins that produce bleeding by interfering with fibrin’s activity. For instance, bleeding may result from bites from the eastern and western diamondback rattlesnakes, the saw-scaled viper, the viperine, the Russell viper, a species of caterpillar found in Venezuela and Brazil (Lonoma achelous), and the brown recluse spider. These venoms often produce symptoms of disseminated intravascular coagulation(DIC) and should be treated with antivenin and transfusion if necessary.
GENERAL DISCLAIMER: This web site and its contents are designed for educational purposes only. This web site does not render medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.
Updated: October 30, 2000