In people without a detectable thrombophilia, the cumulative risk of developing thrombosis by the age of 60 is about 12%. About 60% of people who are deficient in antithrombin will have experienced thrombosis at least once by age 60, as will about 50% of people with protein C deficiency and about a third of those with protein S deficiency. People with activated protein C resistance (usually resulting from factor V Leiden), in contrast, have a slightly raised absolute risk of thrombosis, with 15% having had at least one thrombotic event by the age of sixty. In general, men are more likely than women to experience repeated episodes of venous thrombosis.

People with factor V Leiden are at a relatively low risk of thrombosis, but may develop thrombosis in the presence of an additional risk factor, such as immobilization. Most people with the prothrombin mutation (G20210A) never develop thrombosis.

There are autoimmune causes of coagulation disorders. They include acquired antibodies to coagulation factors, termed inhibitors of coagulation. The main inhibitor is directed against clotting Factor VIII. Another example is antiphospholipid syndrome an autoimmune, hypercoagulable state.

Purpura fulminans is rare and most commonly occurs in babies and small children but can also be a rare manifestation in adults when it is associated with severe infections. For example, Meningococcal septicaemia is complicated by purpura fulminans in 10–20% of cases among children. Purpura fulminans associated with congenital (inherited) protein C deficiency occurs in 1:500,000–1,000,000 live births.

Following are some complications of coagulopathies, some of them caused by their treatments:

Prognosis varies depending on the underlying disorder, and the extent of the intravascular thrombosis (clotting). The prognosis for those with DIC, regardless of cause, is often grim: Between 20% and 50% of patients will die. DIC with sepsis (infection) has a significantly higher rate of death than DIC associated with trauma.

The amount of fresh frozen plasma required to reverse disseminated intravascular coagulation associated with purpura fulminans may lead to complications of fluid overload and death, especially in neonates, such as transfusion-related acute lung injury. Exposure to multiple plasma donors over time increases the cumulative risk for transfusion-associated viral infection and allergic reaction to donor proteins found in fresh frozen plasma.

Allergic reactions and alloantibody formation are also potential complications, as with any protein replacement therapy.

Concomitant warfarin therapy in subjects with congenital protein C deficiency is associated with an increased risk of warfarin skin necrosis.

DIC is observed in approximately 1% of academic hospital admissions. DIC occurs at higher rates in people with bacterial sepsis (83%), severe trauma (31%), and cancer (6.8%).

The major ("type 1") thrombophilias are rare. Antithrombin deficiency is present in 0.2% of the general population and 0.5–7.5% of people with venous thrombosis. Protein C deficiency, too, is present in 0.2% of the population, and can be found in 2.5–6% of people with thrombosis. The exact prevalence of protein S deficiency in the population is unknown; it is found 1.3–5% of people with thrombosis.

The minor ("type 2") thrombophilias are much more common. Factor V Leiden is present in 5% of the population of Northern European descent, but much rarer in those of Asian or African extraction. In people with thrombosis, 10% have factor V Leiden. In those who are referred for thrombophilia testing, 30–50% have the defect. The prothrombin mutation occurs at rates of 1–4% in the general population, 5–10% of people with thrombosis, and 15% of people referred for thrombophilia testing. Like factor V Leiden, this abnormality is uncommon in Africans and Asians.

The exact prevalence of antiphospholipid syndrome is not well known, as different studies employ different definitions of the condition. Antiphospholipid antibodies are detected in 24% of those referred to thrombophilia testing.

Secondary TTP is diagnosed when the patient's history mentions one of the known features associated with TTP. It comprises about 40% of all cases of TTP. Predisposing factors are:

- Cancer

- Bone marrow transplantation

- Pregnancy

- Medication use:

- Antiviral drugs (acyclovir)

- Certain chemotherapy medications such as gemcitabine and mitomycin C

- Quinine

- Oxymorphone

- Quetiapine

- Bevacizumab

- Sunitinib

- Platelet aggregation inhibitors (ticlopidine, clopidogrel, and prasugrel)

- Immunosuppressants (ciclosporin, mitomycin, tacrolimus/FK506, interferon-α)

- Hormone altering drugs (estrogens, contraceptives, hormone replacement therapy)

- HIV-1 infection

The mechanism of secondary TTP is poorly understood, as ADAMTS13 activity is generally not as depressed as in idiopathic TTP, and inhibitors cannot be detected. Probable etiology may involve, at least in some cases, endothelial damage, although the formation of thrombi resulting in vessel occlusion may not be essential in the pathogenesis of secondary TTP. These factors may also be considered a form of secondary aHUS; patients presenting with these features are, therefore, potential candidates for anticomplement therapy.

The mortality rate is around 95% for untreated cases, but the prognosis is reasonably favorable (80–90% survival) for patients with idiopathic TTP diagnosed and treated early with plasmapheresis.

The normal clotting process depends on the interplay of various proteins in the blood. Coagulopathy may be caused by reduced levels or absence of blood-clotting proteins, known as clotting factors or coagulation factors. Genetic disorders, such as hemophilia and Von Willebrand's disease, can cause a reduction in clotting factors.

Anticoagulants such as warfarin will also prevent clots from forming properly. Coagulopathy may also occur as a result of dysfunction or reduced levels of platelets (small disk-shaped bodies in the bloodstream that aid in the clotting process).

Individuals experiencing episodic bleeding as a result of congenital dysfibrinogenemia should be treated at a center specialized in treating hemophilia. They should avoid all medications that interfere with normal platelet function. During bleeding episodes, treatment with fibrinogen concentrates or in emergencies or when these concentrates are unavailable, infusions of fresh frozen plasma and/or cryoprecipitate (a fibrinogen-rich plasma fraction) to maintain fibrinogen activity levels >1 gram/liter. Tranexamic acid or fibrinogen concentrates are recommended for prophylactic treatment prior to minor surgery while fibrinogen concentrates are recommended prior to major surgery with fibrinogen concentrates usage seeking to maintain fibrinogen activity levels at >1 gram/liter. Women undergoing vaginal or Cesarean child birth should be treated at a hemophilia center with fibrinogen concentrates to maintain fibrinogen activity levels at 1.5 gram/liter. The latter individuals require careful observation for bleeding during their post-partum periods.

Individuals experiencing episodic thrombosis as a result of congenital dysfibrinogenemia should also be treated at a center specialized in treating hemophilia using antithrombotic agents. They should be instructed on antithrombotic behavioral methods fur use in high risk situations such as long car rides and air flights. Venous thrombosis should be treated with low molecular weight heparin for a period that depends on personal and family history of thrombosis events. Prophylactic treatment prior to minor surgery should avoid fibrinogen supplementation and use prophylactic anticoagulation measures; prior to major surgery, fibrinogen supplementation should be used only if serious bleeding occurs; otherwise, prophylactic anticoagulation measures are recommended.

Treatment of asymptomatic congenital dysfibrinogenemia depends in part on the expectations of developing bleeding and/or thrombotic complications as estimated based on the history of family members with the disorder and, where available, determination of the exact mutation causing the disorder plus the propensity of the particular mutation type to develop these complications. In general, individuals with this disorder require regular follow-up and multidiscipline management prior to surgery, pregnancy, and giving childbirth. Women with the disorder appear to have an increased rate of miscarriages and all individuals with fibrinogen activity in clotting tests below 0.5 grams/liter are prone to bleeding and spontaneous abortions. Women with multiple miscarriages and individuals with excessively low fibrinogen activity levels should be considered for prophylaxis therapy with fibrinogen replacement during pregnancy, delivery, and/or surgery.

Like most aspects of the disorder, life expectancy varies with severity and adequate treatment. People with severe haemophilia who don't receive adequate, modern treatment have greatly shortened lifespans and often do not reach maturity. Prior to the 1960s when effective treatment became available, average life expectancy was only 11 years. By the 1980s the life span of the average haemophiliac receiving appropriate treatment was 50–60 years. Today with appropriate treatment, males with haemophilia typically have a near normal quality of life with an average lifespan approximately 10 years shorter than an unaffected male.

Since the 1980s the primary leading cause of death of people with severe haemophilia has shifted from haemorrhage to HIV/AIDS acquired through treatment with contaminated blood products. The second leading cause of death related to severe haemophilia complications is intracranial haemorrhage which today accounts for one third of all deaths of people with haemophilia. Two other major causes of death include hepatitis infections causing cirrhosis and obstruction of air or blood flow due to soft tissue haemorrhage.

The prevalence of vWD is about one in 100 individuals. However, the majority of these people do not have symptoms. The prevalence of clinically significant cases is one per 10,000. Because most forms are rather mild, they are detected more often in women, whose bleeding tendency shows during menstruation. It may be more severe or apparent in people with blood type O.

With treatment, maternal mortality is about 1 percent, although complications such as placental abruption, acute renal failure, subcapsular liver hematoma, permanent liver damage, and retinal detachment occur in about 25% of women. Perinatal mortality (stillbirths plus death in infancy) is between 73 and 119 per 1000 babies of woman with HELLP, while up to 40% are small for gestational age. In general, however, factors such as gestational age are more important than the severity of HELLP in determining the outcome in the baby.

If someone has coagulopathy, their health care provider may help them manage their symptoms with medications or replacement therapy. In replacement therapy, the reduced or absent clotting factors are replaced with proteins derived from human blood or created in the laboratory. This therapy may be given either to treat bleeding that has already begun or to prevent bleeding from occurring.

Haemophilia A occurs in approximately 1 in 5,000 males, while the incidence of haemophilia B is 1 in 30,000 in male population, of these, 85% have haemophilia A and 15% have hemophilia B.

Two Dutch studies have followed hemophilia patients for a number of years. Both studies found that viral infections were common in hemophiliacs due to the frequent blood transfusions which put them at risk of getting blood borne infections such as HIV and hepatitis C. In the latest study which followed patients from 1992 to 2001, the male life expectancy was 59 years. If cases with known viral infections were excluded, the life expectancy was 72, close to that of the general population. 26% of the cases died from AIDS and 22% from hepatitis C.

It is known that diabetes causes changes to factors associated with coagulation and clotting, however not much is known of the risk of thromboembolism, or clots, in diabetic patients. There are some studies that show that diabetes increases the risk of thromboembolism; other studies show that diabetes does not increase the risk of thromboembolism. A study conducted in the Umea University Hospital, in Sweden, observed patients that were hospitalized due to an thromboembolism from 1997 to 1999. The researchers had access to patient information including age, sex, vein thromboembolism diagnosis, diagnostic methods, diabetes type and medical history. This study concluded that there is, in fact, an increased risk of thromboembolism development in diabetic patients, possibly due to factors associated with diabetes or diabetes itself. Diabetic patients are twice as likely to develop a thromboembolism than are non-diabetic patient. The exact mechanism of how diabetes increases the risk of clot formation remains unclear and could possibly be a future direction for study.

From previous studies, it is known that long distance air travel is associated with high risk of venous thrombosis. Long periods of inactivity in a limited amount of space may be a reason for the increased risk of blood clot formation. In addition, bent knees compresses the vein behind the knee (the popliteal vein) and the low humidity, low oxygen, high cabin pressure and consumption of alcohol concentrate the blood. A recent study, published in the British Journal of Haematology in 2014, determined which groups of people, are most at risk for developing a clot during or after a long flight. The study focused on 8755 frequent flying employees from international companies and organizations. It found that travelers who have recently undergone a surgical procedure or who have a malignant disease such as cancer or who are pregnant are most at risk. Preventative measures before flying may be taken in these at-risk groups as a solution.

Patients who have undergone kidney transplant have a high risk of developing RVT (about 0.4% to 6%). RVT is known to account for a large proportion of transplanted kidney failures due to technical problems (damage to the renal vein), clotting disorders, diabetes, consumption of ciclosporin or an unknown problem. Patients who have undergone a kidney transplant are commonly prescribed ciclosporin, an immunosuppressant drug which is known to reduce renal blood flow, increase platelet aggregation in the blood and cause damage to the endothelial tissue of the veins. In a clinical study conducted by the Nuffield Department of Surgery at the Oxford Transplant Centre, UK, transplant patients were given low doses of aspirin, which has a some anti-platelet activity. There is risk of bleeding in transplant patients when using anticoagulants like warfarin and herapin. Low dosage of aspirin was used as an alternative. The study concluded that a routine low-dose of aspirin in kidney transplant patients who are also taking ciclosporin significantly reduces the risk of RVT development.

Females possess two X-chromosomes, males have one X and one Y-chromosome. Since the mutations causing the disease are X-linked recessive, a female carrying the defect on one of her X-chromosomes may not be affected by it, as the equivalent allele on her other chromosome should express itself to produce the necessary clotting factors, due to X inactivation. However, the Y-chromosome in the male has no gene for factors VIII or IX. If the genes responsible for production of factor VIII or factor IX present on a male's X-chromosome are deficient there is no equivalent on the Y-chromosome to cancel it out, so the deficient gene is not masked and the disorder will develop.

Since a male receives his single X-chromosome from his mother, the son of a healthy female silently carrying the deficient gene will have a 50% chance of inheriting that gene from her and with it the disease; and if his mother is affected with haemophilia, he will have a 100% chance of being a haemophiliac. In contrast, for a female to inherit the disease, she must receive two deficient X-chromosomes, one from her mother and the other from her father (who must therefore be a haemophiliac himself). Hence haemophilia is far more common among males than females. However, it is possible for female carriers to become mild haemophiliacs due to lyonisation (inactivation) of the X-chromosomes. Haemophiliac daughters are more common than they once were, as improved treatments for the disease have allowed more haemophiliac males to survive to adulthood and become parents. Adult females may experience menorrhagia (heavy periods) due to the bleeding tendency. The pattern of inheritance is criss-cross type. This type of pattern is also seen in colour blindness.

A mother who is a carrier has a 50% chance of passing the faulty X-chromosome to her daughter, while an affected father will always pass on the affected gene to his daughters. A son cannot inherit the defective gene from his father. This is a recessive trait and can be passed on if cases are more severe with carrier. Genetic testing and genetic counselling is recommended for families with haemophilia. Prenatal testing, such as amniocentesis, is available to pregnant women who may be carriers of the condition.

As with all genetic disorders, it is of course also possible for a human to acquire it spontaneously through mutation, rather than inheriting it, because of a new mutation in one of their parents' gametes. Spontaneous mutations account for about 33% of all cases of haemophilia A. About 30% of cases of haemophilia B are the result of a spontaneous gene mutation.

If a female gives birth to a haemophiliac son, either the female is a carrier for the blood disorder or the haemophilia was the result of a spontaneous mutation. Until modern direct DNA testing, however, it was impossible to determine if a female with only healthy children was a carrier or not. Generally, the more healthy sons she bore, the higher the probability that she was not a carrier.

If a male is afflicted with the disease and has children with a female who is not even a carrier, his daughters will be carriers of haemophilia. His sons, however, will not be affected with the disease. The disease is X-linked and the father cannot pass haemophilia through the Y-chromosome. Males with the disorder are then no more likely to pass on the gene to their children than carrier females, though all daughters they sire will be carriers and all sons they father will not have haemophilia (unless the mother is a carrier).

KMS has a mortality rate of about 30%. For patients that survive the acute disease, supportive care may be required through a gradual recovery.

Furthermore, patients may need care from a dermatologist or plastic surgeon for residual cosmetic lesions. On long-term followup, most patients have skin discoloration and/or mild disfiguration from the dormant tumor.

Congenital hypofibrinogenemia is a rare disorder in which one of the two genes responsible for producing fibrinogen, a critical blood clotting factor, is unable to make a functional fibrinogen glycoprotein because of an inherited mutation. In consequence, liver cells, the normal site of fibrinogen production, make small amounts of this critical coagulation protein, blood levels of fibrinogen are low, and individuals with the disorder may suffer a coagulopathy, i.e. a diathesis or propensity to experience episodes of abnormal bleeding. However, individuals with congenital hypofibringenemia may also suffer episodes of abnormal blood clot formation, i.e. thrombosis. This seemingly paradoxical propensity to develop thrombosis in a disorder causing a decrease in a critical protein for blood clotting may be due to the function of fibrin (the split product of fibrinogen that is the basis for forming blood clots) to promote the lysis or desolution of blood clots. Lower levels of fibrin may reduce the lysis of early fibrin strand depositions and thereby allow these depositions to develop into clots.

Congenital hypofibrinogenemia must be distinguished from: a) congenital afibrinogenemia, a rare disorder in which blood fibrinogen levels are either exceedingly low or undetectable due to mutations in both fibrinogen genes; b) congenital hypodysfibrinogenemia, a rare disorder in which one or more genetic mutations cause low levels of blood fibrinogen, at least some of which is dysfunctional and thereby contributes to excessive bleeding; and c) acquired hypofibrinogenemia, a non-hereditary disorder in which blood fibrinogen levels are low because of e.g. severe liver disease or because of excessive fibrinogen consumption resulting from, e.g. disseminated intravascular coagulation.

Certain gene mutations causing congenital hypfibrinogenemia disrupt the ability of liver cells to secrete fibrinogen. In these instances, the un-mutated gene maintains blood fibrinogen at reduce levels but the mutated gene produces a fibrinogen that accumulates in liver cells sometimes to such extents that it becomes toxic. In the latter cases, liver disease may ensue in a syndrome termed fibrinogen storage disease.

Warfarin necrosis usually occurs three to five days after drug therapy is begun, and a high initial dose increases the risk of its development. Heparin-induced necrosis can develop both at sites of local injection and - when infused intravenously - in a widespread pattern.

In warfarin's initial stages of action, inhibition of protein C and Factor VII is stronger than inhibition of the other vitamin K-dependent coagulation factors II, IX and X. This results from the fact that these proteins have different half-lives: 1.5 to six hours for factor VII and eight hours for protein C, versus one day for factor IX, two days for factor X and two to five days for factor II. The larger the initial dose of vitamin K-antagonist, the more pronounced these differences are. This coagulation factor imbalance leads to paradoxical activation of coagulation, resulting in a hypercoagulable state and thrombosis. The blood clots interrupt the blood supply to the skin, causing necrosis. Protein C is an innate anticoagulant, and as warfarin further decreases protein C levels, it can lead to massive thrombosis with necrosis and gangrene of limbs.

Notably, the prothrombin time (or international normalized ratio, INR) used to test the effect of warfarin is highly dependent on factor VII, which explains why patients can have a therapeutic INR (indicating good anticoagulant effect) but still be in a hypercoagulable state.

In one third of cases, warfarin necrosis occurs in patients with an underlying, innate and previously unknown deficiency of protein C. The condition is related to purpura fulminans, a complication in infants with sepsis (blood stream infection) which also involves skin necrosis. These infants often have protein C deficiency as well. There have also been cases in patients with other deficiency, including protein S deficiency, activated protein C resistance (Factor V Leiden) and antithrombin III deficiency.

Although the above theory is the most commonly accepted theory, others believe that it is a hypersensitivity reaction or a direct toxic effect.

Von Willebrand disease can also affect some breeds of dogs, notably the Doberman Pinscher, and screening is offered for known breeds.