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There is no specific treatment for thrombophilia, unless it is caused by an underlying medical illness (such as nephrotic syndrome), where the treatment of the underlying disease is needed. In those with unprovoked and/or recurrent thrombosis, or those with a high-risk form of thrombophilia, the most important decision is whether to use anticoagulation medications, such as warfarin, on a long-term basis to reduce the risk of further episodes. This risk needs to weighed against the risk that the treatment will cause significant bleeding, as the reported risk of major bleeding is over 3% per year, and 11% of those with major bleeding may die as a result.
Apart from the abovementioned forms of thrombophilia, the risk of recurrence after an episode of thrombosis is determined by factors such as the extent and severity of the original thrombosis, whether it was provoked (such as by immobilization or pregnancy), the number of previous thrombotic events, male sex, the presence of an inferior vena cava filter, the presence of cancer, symptoms of post-thrombotic syndrome, and obesity. These factors tend to be more important in the decision than the presence or absence of a detectable thrombophilia.
Those with antiphospholipid syndrome may be offered long-term anticoagulation after a first unprovoked episode of thrombosis. The risk is determined by the subtype of antibody detected, by the antibody titer (amount of antibodies), whether multiple antibodies are detected, and whether it is detected repeatedly or only on a single occasion.
Women with a thrombophilia who are contemplating pregnancy or are pregnant usually require alternatives to warfarin during pregnancy, especially in the first 13 weeks, when it may produce abnormalities in the unborn child. Low molecular weight heparin (LMWH, such as enoxaparin) is generally used as an alternative. Warfarin and LMWH may safely be used in breastfeeding.
When women experience recurrent pregnancy loss secondary to thrombophilia, some studies have suggested that low molecular weight heparin reduces the risk of miscarriage. When the results of all studies are analysed together, no statistically signifiant benefit could be demonstrated.
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.
As there is no cure, treatment is focused on prevention of thrombotic complications by counseling. In addition, temporary treatment with an anticoagulant may be required during periods of particularly high risk of thrombosis, such as major surgery.
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.
Studies have found that about 5 percent of Caucasians in North America have factor V Leiden. The condition is less common in Latin Americans and African-Americans and is extremely rare in people of Asian descent.
Up to 30 percent of patients who present with deep vein thrombosis (DVT) or pulmonary embolism have this condition. The risk of developing a clot in a blood vessel depends on whether a person inherits one or two copies of the factor V Leiden mutation. Inheriting one copy of the mutation from a parent (heterozygous) increases by fourfold to eightfold the chance of developing a clot. People who inherit two copies of the mutation (homozygous), one from each parent, may have up to 80 times the usual risk of developing this type of blood clot. Considering that the risk of developing an abnormal blood clot averages about 1 in 1,000 per year in the general population, the presence of one copy of the factor V Leiden mutation increases that risk to between 4 in 1,000 to 8 in 1,000. Having two copies of the mutation may raise the risk as high as 80 in 1,000. It is unclear whether these individuals are at increased risk for "recurrent" venous thrombosis. While only 1 percent of people with factor V Leiden have two copies of the defective gene, these homozygous individuals have a more severe clinical condition. The presence of acquired risk factors for venous thrombosis—including smoking, use of estrogen-containing (combined) forms of hormonal contraception, and recent surgery—further increase the chance that an individual with the factor V Leiden mutation will develop DVT.
Women with factor V Leiden have a substantially increased risk of clotting in pregnancy (and on estrogen-containing birth control pills or hormone replacement) in the form of deep vein thrombosis and pulmonary embolism. They also may have a small increased risk of preeclampsia, may have a small increased risk of low birth weight babies, may have a small increased risk of miscarriage and stillbirth due to either clotting in the placenta, umbilical cord, or the fetus (fetal clotting may depend on whether the baby has inherited the gene) or influences the clotting system may have on placental development. Note that many of these women go through one or more pregnancies with no difficulties, while others may repeatedly have pregnancy complications, and still others may develop clots within weeks of becoming pregnant.
For people who have severe congenital protein C deficiency, protein C replacement therapies are available, which is indicated and approved for use in the United States and Europe for the prevention of purpura fulminans. Protein C replacement is often in combination with anticoagulation therapy of injectable low molecular weight heparin or oral warfarin. Before initiating warfarin therapy, a few days of therapeutic heparin may be administered to prevent warfarin skin necrosis and other progressive or recurrent thrombotic complications.
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.
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.
Clotting factors are usually not needed in mild haemophilia. In moderate haemophilia clotting factors are typically only needed when bleeding occurs or to prevent bleeding with certain events. In severe haemophilia preventive use is often recommended two or three times a week and may continue for life. Rapid treatment of bleeding episodes decreases damage to the body.
Factor VIII is used in haemophilia A and factor IX in haemophilia B. Factor replacement can be either isolated from human blood serum, recombinant, or a combination of the two. Some people develop antibodies (inhibitors) against the replacement factors given to them, so the amount of the factor has to be increased or non-human replacement products must be given, such as porcine factor VIII.
If a person becomes refractory to replacement coagulation factor as a result of circulating inhibitors, this may be partially overcome with recombinant human factor VII.
In early 2008, the US Food and Drug Administration (FDA) approved anti-haemophilic factor, genetically engineered from the genes of Chinese hamster ovary cells. Since 1993 recombinant factor products (which are typically cultured in Chinese hamster ovary (CHO) tissue culture cells and involve little, if any human plasma products) have been available and have been widely used in wealthier western countries. While recombinant clotting factor products offer higher purity and safety, they are, like concentrate, extremely expensive, and not generally available in the developing world. In many cases, factor products of any sort are difficult to obtain in developing countries.
Clotting factors are either given preventively or on-demand. Preventive use involves the infusion of clotting factor on a regular schedule in order to keep clotting levels sufficiently high to prevent spontaneous bleeding episodes. On-demand (or episodic) treatment involves treating bleeding episodes once they arise. In 2007, a trial comparing on-demand treatment of boys (< 30 months) with haemophilia A with prophylactic treatment (infusions of 25 IU/kg body weight of Factor VIII every other day) in respect to its effect on the prevention of joint-diseases. When the boys reached 6 years of age, 93% of those in the prophylaxis group and 55% of those in the episodic-therapy group had a normal index joint-structure on MRI. Prophylactic treatment, however, resulted in average costs of $300,000 per year. The author of an editorial published in the same issue of the "NEJM" supports the idea that prophylactic treatment not only is more effective than on demand treatment but also suggests that starting after the first serious joint-related haemorrhage may be more cost effective than waiting until the fixed age to begin.
The 2012 ACCP guidelines offered weak recommendations. For at-risk long-haul travelers—those with "previous VTE, recent surgery or trauma, active malignancy, pregnancy, estrogen use, advanced age, limited mobility, severe obesity, or known thrombophilic disorder"—suggestions included calf exercises, frequent walking, and aisle seating in airplanes to ease walking. The use of graduated compression stockings that fit below the knee and give 15–30 mm Hg of pressure to the ankle was suggested, while aspirin or anticoagulants were not. Compression stockings have sharply reduced the levels of asymptomatic DVT in airline passengers, but the effect on symptomatic VTE is unknown, as none of the individuals studied developed symptomatic VTE.
The course of treatment and the success rate is dependent on the type of TMA. Some patients with atypical HUS and TTP have responded to plasma infusions or exchanges, a procedure which replaces proteins necessary for the complement cascade that the patient does not have; however, this is not a permanent solution or treatment, especially for patients with congenital predispositions.
While there is no cure for haemophilia, treatment improves outcomes.
The risk of VTE is increased in pregnancy by about five times because of a more hypercoagulable state, a likely adaptation against fatal postpartum hemorrhage. Additionally, pregnant women with genetic risk factors are subject to a roughly three to 30 times increased risk for VTE. Preventative treatments for pregnancy-related VTE in hypercoagulable women were suggested by the ACCP. Homozygous carriers of factor V Leiden or prothrombin G20210A with a family history of VTE were suggested for antepartum LMWH and either LMWH or a vitamin K antagonist (VKA) for the six weeks following childbirth. Those with another thrombophilia and a family history but no previous VTE were suggested for watchful waiting during pregnancy and LMWH or—for those without protein C or S deficiency—a VKA. Homozygous carriers of factor V Leiden or prothrombin G20210A with no personal or family history of VTE were suggested for watchful waiting during pregnancy and LMWH or a VKA for six weeks after childbirth. Those with another thrombophilia but no family or personal history of VTE were suggested for watchful waiting only. Warfarin, a common VKA, can cause harm to the fetus and is not used for VTE prevention during pregnancy.
Surgery to remove the clot is possible, but rarely performed. In the past, surgical removal of the renal vein clot was the primary treatment but it is very invasive and many complications can occur. In the past decades, treatment has shifted its focus from surgical intervention to medical treatments that include intravenous and oral anticoagulants. The use of anticoagulants may improve renal function in RVT cases by removing the clot in the vein and preventing further clots from occurring. Patients already suffering from nephrotic syndrome may not need to take anticoagulants. In this case, patients should keep an eye out and maintain reduced level of proteinuria by reducing salt and excess protein, and intaking diuretics and statins. Depending on the severity of RVT, patients may be on anticoagulants from a year up to a lifetime. As long as the albumen levels in the bloodstream are below 2.5g/L, it is recommended that RVT patients continue taking anticoagulants. Main anticoagulants that can be used to treat RVT include warfarin and low molecular weight heparin. Heparin has become very popular, because of its low risk of complications, its availability and because it can easily be administered. Warfarin is known to interact with many other drugs, so careful monitoring is required. If a nephrotic syndrome patient experiences any of the RVT symptoms (flank or back pain, blood in the urine or decreased renal function), he or she should immediately see a doctor to avoid further complications.
The main side effect of anticoagulants is the risk of excessive bleeding. Other side effects include: blood in the urine or feces, severe bruising, prolonged nosebleeds (lasting longer than 10 minutes), bleeding gum, blood in your vomit or coughing up blood, unusual headaches, sudden severe back pain, difficulty breathing or chest pain, in women, heavy or increased bleeding during the period, or any other bleeding from the vagina. Warfarin can cause rashes, diarrhea, nausea (feeling sick) or vomiting, and hair loss. Heparin can cause hair loss (alopecia) thrombocytopenia – a sudden drop in the number of platelets in the blood.
It has been reported in a case study of 27 patients with nephrotic syndrome caused RVT, there was a 40% mortality rate, mostly due to hemorrhagic complications and sepsis. In 75% of the remaining surviving patients, the RVT was resolved and renal function returned to normal. It has been concluded that age is not a factor on the survival of RVT patients, although older patient (55 and older) are more likely to develop renal failure. Heparin is crucial in returning normal renal function; in patients that did not take heparin, long term renal damage was observed in 100%. In patients that did take heparin, renal damage was observed in about 33%. By quickly treating, and receiving the correct medications, patients should increase their chances of survival and reduce the risk of the renal vein clot from migrating to another part of the body.
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.
Treatment for Thrombotic Storm may include lifelong anticoagulation therapy and/or thrombolytic therapy, plasmapherisis, and corticosteroids. Studies have shown that when anticoagulant therapy is withheld recurrence of thrombosis usually follows. INR is closely monitored in the course of treatment.
There are too few cases of fibrinogen storage disease to establish optimal treatments for the liver diseases. Management of the disorder has been based on general recommendations for patients with liver disease, particularly Alpha 1 antitrypsin deficiency-associated liver disease. In the latter disease, autophagy, the pathway that cells use to dispose of dysfunctional or excessively stored components including proteins, has been targeted using autophagy-enhancing drugs, e.g. carbamazepine, vitamin E, and ursodeoxycholic acid. These drugs have been tested in individual patients with fibrin storage disease with some success in reducing evidence of liver injure, i.e. reduction in blood liver enzyme levels. These and other autophagy-enhancing drugs are suggested to be further studied in fibrinogen storage disease.
Therapy involves both preventive measures and treatment of specific bleeding episodes.
- Dental hygiene lessens gingival bleeding
- Avoidance of antiplatelet agents such as aspirin and other anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen, and anticoagulants
- Iron or folate supplementation may be necessary if excessive or prolonged bleeding has caused anemia
- Hepatitis B vaccine
- Antifibrinolytic drugs such as tranexamic acid or ε-aminocaproic acid (Amicar)
- Desmopressin (DDAVP) does not normalize the bleeding time in Glanzmann's thrombasthenia but anecdotally improves hemostasis
- Hormonal contraceptives to control excessive menstrual bleeding
- Topical agents such as gelfoam, fibrin sealants, polyethylene glycol polymers, custom dental splints
- Platelet transfusions (only if bleeding is severe; risk of platelet alloimmunization)
- Recombinant factor VIIa, AryoSeven or NovoSeven FDA approved this drug for the treatment of the disease on July 2014.
- Hematopoietic stem cell transplantation (HSCT) for severe recurrent hemorrhages
Heparin enhances ATIII activity and neutralizes "activated serine protease coagulation factors." Patients with ATIII deficiency requiring anticoagulant therapy with heparin will need higher doses of heparin. ATIII binds to thrombin and then forms the thrombin-anti thrombin complex or TAT complex. This is a major natural pathway of anticoagulation. This binding of thrombin to AT is greatly enhanced in the presence of heparin. Heparin does not affect vitamin K metabolism, so giving vitamin K1 (Phytonadione) will not reverse the effects of heparin.
Heparin is used as "bridging" therapy when initiating a patient on warfarin in a hospital setting. It can be used in DVT prophylaxis and treatment, acute coronary syndromes, and ST-segment elevated MI.
Treatment of DIC is centered around treating the underlying condition. Transfusions of platelets or fresh frozen plasma can be considered in cases of significant bleeding, or those with a planned invasive procedure. The target goal of such transfusion depends on the clinical situation. Cryoprecipitate can be considered in those with a low fibrinogen level.
Treatment of thrombosis with anticoagulants such as heparin is rarely used due to the risk of bleeding.
Recombinant human activated protein C was previously recommended in those with severe sepsis and DIC, but drotrecogin alfa has been shown to confer no benefit and was withdrawn from the market in 2011.
Recombinant factor VII has been proposed as a "last resort" in those with severe hemorrhage due to obstetric or other causes, but conclusions about its use are still insufficient.
Following are some complications of coagulopathies, some of them caused by their treatments:
The long-term prognosis for APS is determined mainly by recurrent thrombosis, which may occur in up to 29% of patients, sometimes despite antithrombotic therapy.
For patients with vWD type 1 and vWD type 2A, desmopressin is available as different preparations, recommended for use in cases of minor trauma, or in preparation for dental or minor surgical procedures. Desmopressin stimulates the release of vWF from the Weibel-Palade bodies of endothelial cells, thereby increasing the levels of vWF (as well as coagulant factor VIII) three- to five-fold. Desmopressin is also available as a preparation for intranasal administration (Stimate) and as a preparation for intravenous administration. Recently, the FDA has approved the use of Baxalta’s Vonvendi. This is the first recombinant form of vWF. The effectiveness of this treatment is different than desmopressin because it only contains vWF, not vWF with the addition of FVIII. This treatment is only recommended for use by individuals who are 18 years of age or older.
Desmopressin is contraindicated in vWD type 2b because of the risk of aggravated thrombocytopenia and thrombotic complications. Desmopressin is probably not effective in vWD type 2M and is rarely effective in vWD type 2N. It is totally ineffective in vWD type 3.
For women with heavy menstrual bleeding, estrogen-containing oral contraceptive medications are effective in reducing the frequency and duration of the menstrual periods. Estrogen and progesterone compounds available for use in the correction of menorrhagia are ethinylestradiol and levonorgestrel (Levona, Nordette, Lutera, Trivora). Administration of ethinylestradiol diminishes the secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary, leading to stabilization of the endometrial surface of the uterus.
Desmopressin is a synthetic analog of the natural antidiuretic hormone vasopressin. Its overuse can lead to water retention and dilutional hyponatremia with consequent convulsion.
For patients with vWD scheduled for surgery and cases of vWD disease complicated by clinically significant hemorrhage, human-derived medium purity factor VIII concentrates, which also contain von Willebrand factors, are available for prophylaxis and treatment. Humate P, Alphanate, Wilate and Koate HP are commercially available for prophylaxis and treatment of vWD. Monoclonally purified factor VIII concentrates and recombinant factor VIII concentrates contain insignificant quantity of vWF, so are not clinically useful.
Development of alloantibodies occurs in 10-15% of patients receiving human-derived medium-purity factor VIII concentrates and the risk of allergic reactions including anaphylaxis must be considered when administering these preparations. Administration of the latter is also associated with increased risk of venous thromboembolic complications.
Blood transfusions are given as needed to correct anemia and hypotension secondary to hypovolemia. Infusion of platelet concentrates is recommended for correction of hemorrhage associated with platelet-type vWD.
The antifibrinolytic agents epsilon amino caproic acid and tranexamic acid are useful adjuncts in the management of vWD complicated by clinical hemorrhage. The use topical thrombin JMI and topical Tisseel VH are effective adjuncts for correction of hemorrhage from wounds.
The first element of treatment is usually to discontinue the offending drug, although there have been reports describing how the eruption evolved little after it had established in spite of continuing the medication. Vitamin K1 can be used to reverse the effects of warfarin, and heparin or its low molecular weight heparin (LMWH) can be used in an attempt to prevent further clotting. None of these suggested therapies have been studied in clinical trials.
Heparin and LMWH act by a different mechanism than warfarin, so these drugs can also be used to prevent clotting during the first few days of warfarin therapy and thus prevent warfarin necrosis (this is called 'bridging').
Based on the assumption that low levels of protein C are involved in the underlying mechanism, common treatments in this setting include fresh frozen plasma or pure activated protein C.
Since the clot-promoting effects of starting administration of 4-hydroxycoumarins are transitory, patients with protein C deficiency or previous warfarin necrosis can still be restarted on these drugs if appropriate measures are taken. These include gradual increase starting from low doses and supplemental administration of protein C (pure or from fresh frozen plasma).
The necrotic skin areas are treated as in other conditions, sometimes healing spontaneously with or without scarring, sometimes going on to require surgical debridement or skin grafting.
Individuals with hypofibrinogenemia who have a history of excessive bleeding should be treated at a center specialized in treating hemophilia and avoid all medications that interfere with normal platelet function. During bleeding episodes, treatment with fibrinogen concentrates or, if unavailable infusion of fresh frozen plasma and/or cryoprecipitate (a fibrinogen-rich plasma fraction) to maintain fibrinogen activity levels >1 gram/liter.
Individuals with hypofibrinogenemia who experience episodic thrombosis should also be treated at a center specialized in treating hemophilia. Standard recommendations for these individuals are that they use antithrombotic agents and be instructed on antithrombotic behavioral methods in high risk situations (e.g. long car rides and air flights]]. Acute venous thrombosis episodes should be treated with low molecular weight heparin for a time that depends on personal and family history of thrombosis events. Prophylactic treatment prior to minor surgery should avoid fibrinogen supplementation and use anticoagulation measures; prior to major surgery, fibrinogen supplementation should be used only if serious bleeding occurs; otherwise, prophylactic anticoagulation measures are recommended.