Why Does Coagulation Fail?
The failure of blood clot formation can cause bleeding complications during or after an oral surgery procedure. Normal coagulation may fail due to several reasons.
Thrombocytopenia
In thrombocytopenia, the platelet blood count is below the normal levels of 150,000-350,000 platelets per mm3. Below a count of 50,000, one can expect abnormal and spontaneous bleeding, if the level decreases to below 10,000. Platelet deficiency can result from:
- Failure of bone marrow to produce enough platelets (disorders, vitamin deficiency, aplastic anemia, infections, alcohol consumption, etc.)
- Enlarged spleen which traps platelets
- Dilution of platelets (heart bypass surgery, blood or fluid replacement etc.)
- Platelet destruction or use (EBV, HIV, SLE, various medications)
- Increased platelet use (disseminated intravascular coagulation (DIC) etc.)
von Willebrands’ Disease (VWD)
VWD is a hereditary condition in which a protein that affects platelets is missing. In this condition, platelets fail to clump and plug vessel walls. There are four types, I, IIa, IIb, III and IV in order of severity and rarity. While it may not be necessary to treat all patients pre-operatively, a hematology consult should be obtained.
Hemophilia
Hemophilia is another hereditary condition characterized by decreased amounts of coagulation factors VIII and IX. Hemophilia A accounts for ~80% of cases and involves factor VIII; Hemophilia B or Christmas disease involves factor IX. The disease affects mostly males and is inherited through the mother.
Disseminated Intravascular Coagulation (DIC)
In DIC, small blood clots form and travel through the bloodstream where they may cause blockages in smaller vessels. As such, excessive clotting factors are used up. This is often seen in certain leukemias, pancreatic, stomach or prostate cancer. In other instances, it may arise from a toxic substance in the blood including bacterial endotoxins or uterine tissue from a complex obstetric surgery.
Disseminated Malignancy
This condition is often associated with the presence of tumour cells in bone marrow which impairs the coagulation pathway or system. Additionally, there may be deficiencies of isolated factors.
Anemia
Anemia contributes to bleeding problems and can take different forms.
- Complication of chronic renal failure
-Requires dialysis and replacement therapy
- Cancer-related autoimmune hemolytic anemia
-Ovarian cancer, lymphoma, lung, stomach, breast, kidney, colon, testicular cancers
- Resulting from pituitary deficiency, para/thyroid as well as adrenal diseases
Bacterial Infections – Chronic/Acute
The presence of hypervascular and granulomatous tissue are often associated with bacterial infections. Bacteria within an area of infection release toxins that affect the endothelium of vascular walls and can adversely affect liver function as well as hemostasis.
Viral Infections
Certain viral infections including rubella, cytomegalovirus (CMV) and HIV can negatively impact blood clotting. In HIV, along with thrombocytopenia, there is also a deficiency in lymphocytes and neutrophils, lymphopenia and neutropenia, respectively. Patients treated with AZT (zidovudine) are at risk for development of drug-induced bone marrow hypoplasia.
Parasitic Infections
Diseases such as malaria, hookworm, visceral larva migrans, schistosomiasis, leishmaniasis and other trematode infections affect coagulation.
Systemic Lupus Erythematosus (SLE)
In SLE, antibodies against lipids involved in clotting are produced by the body which can attack blood cells, organs and tissues. As a result, blood clots may form and cause pulmonary embolism, miscarriages, hemoptysis, strokes etc. SLE can also result in thrombocytopenia and anemia.
Rheumatoid Arthritis
Patients afflicted with rheumatoid arthritis may also be anemic as a result of poor diets, chronic blood loss or due to treatment with anti-inflammatory medication such as NSAIDs, ASA and corticosteroids.
Inflammatory Bowel Diseases
Many of the medications used to treat these diseases exacerbate the issue.
Liver Disease
Clotting factors required for coagulation are reduced in people afflicted by liver disease. Additionally, patients with chronic liver failure as well as alcoholics are usually anemic. Alcoholics may also suffer toxic effects on bone marrow which further impacts bleeding.
Pneumonia
Patients with pneumonia as a result of Legionella pneumophilia can have severe thrombocytopenia and lymphopenia as well as complications due to DIC.
Source: Manual of Minor Oral Surgery for the General Dentist, Wiley, 2006