Thrombosis prevention or thromboprophylaxis is medical treatment to prevent the development of

thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (t ...

(blood clots inside blood vessels) in those considered at risk for developing thrombosis. Some people are at a higher

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environm ...

for the formation of blood clots than others, such as those with cancer undergoing a surgical procedure. Prevention measures or interventions are usually begun after surgery as the associated immobility will increase a person's risk. Blood thinners are used to prevent clots, these blood thinners have different effectiveness and safety profiles. A 2018 systematic review found 20 studies that included 9771 people with cancer. The evidence did not identify any difference between the effects of different blood thinners on death, developing a clot, or bleeding. A 2021 review found that

low molecular weight heparin Low-molecular-weight heparin (LMWH) is a class of anticoagulant medications. They are used in the prevention of blood clots and treatment of venous thromboembolism (deep vein thrombosis and pulmonary embolism) and in the treatment of myocardial in ...

(LMWH) was superior to unfractionated heparin in the initial treatment of

venous thromboembolism Venous thrombosis is blockage of a vein caused by a thrombus (blood clot). A common form of venous thrombosis is deep vein thrombosis (DVT), when a blood clot forms in the deep veins. If a thrombus breaks off (embolizes) and flows to the lungs to ...

for people with cancer. There are

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

-based

interventions ''Interventions'' is a book by Noam Chomsky, an American academic linguist and political activist. Published in May 2007, ''Interventions'' is a collection of 44 op-ed articles, post-9/11, from September 2002, through March 2007. The book's sub ...

and non-medication-based interventions. The risk of developing blood clots can be lowered by life style modifications, the discontinuation of

oral contraceptive Oral contraceptives, abbreviated OCPs, also known as birth control pills, are medications taken by mouth for the purpose of birth control. Female Two types of female oral contraceptive pill, taken once per day, are widely available: * The combi ...

s, and

weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat ( adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other co ...

. In those at high risk both interventions are often used. The treatments to prevent the formation of blood clots is balanced against the risk of bleeding. One of the goals of blood clot prevention is to limit

venous stasis Venostasis, or venous stasis, is a condition of slow blood flow in the veins, usually of the legs. Presentation Complications Potential complications of venous stasis are: * Venous ulcers * Blood clot formation in veins (venous thrombosis), that ...

as this is a significant risk factor for forming blood clots in the

deep veins A deep vein is a vein that is deep in the body. This contrasts with superficial veins that are close to the body's surface. Deep veins are almost always beside an artery with the same name (e.g. the femoral vein is beside the femoral artery) ...

of the legs. Venous stasis can occur during the long periods of not moving. Thrombosis prevention is also recommended during air travel. Thrombosis prophylaxis is effective in preventing the formation of blood clots, their lodging in the veins, and their developing into thromboemboli that can travel through the

circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

to cause blockage and subsequent tissue death in other

organs In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

Clarence Crafoord Clarence Crafoord (1899 – 1984) was a Swedish cardiovascular surgeon, best known for performing the first successful repair of aortic coarctation on 19 October 1944, one year before Robert E. Gross. Crafoord also introduced heparin as thro ...

is credited with the first use of thrombosis prophylaxis in the 1930s.

Pathophysiology of blood clot prevention

The development of blood clots can be interrupted and prevented by the use of medication, changing

risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often ...

s and other interventions. Some risk factors can be modified. These would be losing weight, increasing exercise and the cessation of oral contraceptives. Moving during periods of travel is a modifiable behavior. Preventing blood clots includes the use of medications that interrupt the complex

clotting cascade Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...

and changing the proteins that are needed for clotting. Antiplatelet drugs also have an effect in preventing the formation of clots.

Medical treatments

Thrombosis prophylaxis is not only used for the prevention of

deep vein thrombosis Deep vein thrombosis (DVT) is a type of venous thrombosis involving the formation of a blood clot in a deep vein, most commonly in the legs or pelvis. A minority of DVTs occur in the arms. Symptoms can include pain, swelling, redness, and enla ...

, but can be initiated for the prevention of the formation of blood clots in other organs and circumstances unrelated to deep vein thrombosis: * cerebral complications *

abortion Abortion is the termination of a pregnancy by removal or expulsion of an embryo or fetus. An abortion that occurs without intervention is known as a miscarriage or "spontaneous abortion"; these occur in approximately 30% to 40% of pre ...

* ectopic pregnancy * molar pregnancy *

pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...

childbirth Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births glob ...

and the

puerperium The postpartum (or postnatal) period begins after childbirth and is typically considered to end within 6 weeks as the mother's body, including hormone levels and uterus size, returns to a non-pregnant state. The terms puerperium, puerperal perio ...

coronary Coronary () may, as shorthand in English, be used to mean: * Coronary circulation, the system of arteries and veins in mammals ** Coronary artery disease **Coronary occlusion ** A myocardial infarction, a heart attack As adjective * Referring to ...

portal vein thrombosis Portal vein thrombosis (PVT) is a vascular disease of the liver that occurs when a blood clot occurs in the hepatic portal vein, which can lead to increased pressure in the portal vein system and reduced blood supply to the liver. The mortality ...

* intracranial, nonpyogenic * intraspinal, nonpyogenic *

mesenteric The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intestine ...

pulmonary The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

Epidemiology of developing blood clots

The risk of developing deep vein thrombosis, or pulmonary embolism is different than the total risk of the formation of blood clots. This is due to the observation that not all blood clots form in the lower legs. Most hospitalized medical patients have at least 1 risk factor for thrombosis that progresses to thromboembolism and this risk persists weeks after discharge. Those who remain undiagnosed and not treated prophylactically have a 26% chance of developing a fatal embolism. Another 26% develop another embolism. Between 5% and 10% of all in hospital deaths are due to pulmonary embolism (as a consequence of thrombosis). Estimates of the incidence of pulmonary embolism in the US is 0.1% persons/year. Hospital admissions in the US for pulmonary embolism are 200,000 to 300,000 yearly. Thrombosis that develops into DVT will affect 900,000 people and kill up to 100,000 in the US. On average 28,726 hospitalized adults aged 18 and older with a VTE blood clot diagnosis die each year. Risk of thrombosis is related to hospitalization. In 2005 the UK the Parliamentary

Health Select Committee The Health and Social Care Select Committee (abbreviated to HSC, HSCC and HSCSC) is a Departmental Select Committee of the British House of Commons, the lower house of the United Kingdom Parliament. Its remit is to examine the policy, administra ...

determined the annual rate of death due to thrombosis was 25,000 with at least 50% being hospital-acquired. The type of surgery performed prior to the formation of blood clots influences the risk. Without prophylactic interventions, the calculated incidence of clot formation in the lower leg veins after surgery is: * 22% for

neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and pe ...

* 26% for

abdominal surgery The term abdominal surgery broadly covers surgical procedures that involve opening the abdomen (laparotomy). Surgery of each abdominal organ is dealt with separately in connection with the description of that organ (see stomach, kidney, liver, etc ...

* 45% for 60% in

orthopedic surgery Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...

* 14% for gynecologic surgery As the population of the US ages, the development of blood clots is becoming more common.

General risks and indications for blood clot prevention

Some risk factors for developing blood clots are considered higher that others. One scoring system analyzes the probability for clot formation by assigning a point value system to significant risk factors. The benefit of treating those who are at low risk of developing blood clots may not outweigh the higher risks of significant bleeding. ::

Risk for subsequent blood clots

Developing blood clots is more probable after the first episode. Risk assessment and intervention for those with one or more episodes of deep vein thrombosis or blood clots in the veins utilizes the Well's test. It has been inconsistently modified by a number of publishers with the results listed below:

Well's and modified Well's risk scoring

Adapted for the emergency department

Scoring: * less than 2 points – low risk (3%) * 2–6 points moderate risk (17%) * > 6 points high risk (75%)

General interventions

The

Centers for Disease Control and Prevention The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

have issued general guidelines describing the interventions that can be taken to reduce the risk of the formation of blood clots: Venous valve 00013

Interventions during travel

Seat-edge pressure from the seat on an airplane on the popliteal area may contribute to vessel wall damage as well as

Coagulation Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...

activation may result from an interaction between cabin conditions (such as

hypobaric A hypobaric chamber, or altitude chamber, is a chamber used during aerospace or high terrestrial altitude research or training to simulate the effects of high altitude on the human body, especially hypoxia (low oxygen) and hypobaria (low ambien ...

hypoxia) and individual risk factors for the formation of blood clots. Studies of the pathophysiologic mechanisms for the increased risk of Venous thrombosis embolism or VTE after long-distance travel have not produced consistent results, but venous stasis appears to play a major role; other factors specific to air travel may increase coagulation activation, particularly in passengers with individual risk factors for VTE.

Interventions for those hospitalized

Compression devices

Mechanical compression devices are used for prevention of thrombosis and are beneficial enough to be used by themselves with patients at low to moderate risk. The use of fitted intermittent pneumatic compression devices before, during and after procedures is used in inpatient settings. It consists of an air pump and inflatable auxiliary compartments that sequentially inflates and deflated to provide an external 'pump' that returns venous blood toward the heart. The use of intermittent pneumatic compression is common. These devices are also placed on a surgical patient in the operating room (the intra-surgical period) and remain on the person while recovering from the surgery. The application of antiembolism stockings can be used to prevent thrombosis. The correct use and properly fitted graded compression stockings can reduce the rate of thrombosis by 50%. Contraindications for the use of antiembolism stockings include the presence of advanced peripheral and obstructive arterial disease, septic phlebitis, heart failure, open wounds, dermatitis and peripheral neuropathy. Differences between the use of thigh-high compression stockings and shorter types to prevent blood clots exist, but remain inconsistent.

Assessment

There has been some success in preventing blood clots by an early risk assessment upon admission to the hospital, which is a strategy recognized by the Centers for Disease Control and Prevention. Hospitals that have participated in this effort to reduce the incidence of thrombosis found that rates of DVT decreased in some instances. Some hospitals developed a mandatory assessment quantifying the risk for developing blood clots and a plan of care developed from the results. The person's risk for developing blood clots is entered into their record, 'following' them through their treatment regime. If the hospital stay exceeds three days, the person will be reassessed for risk. Clinicians are then able to apply protocols for prevention based upon best clinical practices.

Interventions to treat immobility

Immobility is a significant risk factor in the development of thrombosis. Immediate post-surgical interventions, such as out of bed orders (OOB), are typically ordered by the physician to prevent thrombosis. These orders, typically delegated to a nurse, but may include the participation of a physical therapist and others trained to perform the intervention, are to perform range of motion (ROM) activities that include: muscle contractions of the lower legs for those who are very weak, moving the feet, wiggling the toes, bending the knees, raise and lower the legs. In addition, changes in positioning prevents immobility and shifts areas of venous stasis. If the person is too weak to perform these preventative activities, hospital personnel will perform these movements independently. Exercise of the lower extremities is a post-operative method of prophylaxis. Nursing personnel will often perform range of motion exercises and encourage frequent moving of the legs, feet, and ankles. Frequent positioning changes and adequate fluid intake. After a surgical procedure, ambulation as soon as possible is prophylactic in preventing the formation of blood clots. Early ambulation also prevents venous stasis and physicians order OOB activities on the same day of surgery. This is accomplished in increments. The progression of increasing mobility proceeds by: raising the head of the bed, sitting up in bed, moving to the edge of the bed, dangling the legs off the bed and then ambulating to a close chair. Patient education and compliance reduces the risk of developing blood clots. These exercises and use of equipment and follow up by clinicians reduces the risk of developing blood clots. Note that if a blood clot has already formed in the deep veins of the leg, bedrest is usually prescribed and the treatment to prevent bloods with physical intervention is contraindicated.

Medication

Anticoagulants and antiplatelets

Thromboprophylaxis, such as anticoagulants or perioperative heparin, is effective for hospitalized patients at risk for VTE. Additional risk factors such as obesity, disease, malignancies, long surgeries, and immobility may influence the prescribed dosage. Anticoagulant medications may prevent the formation of blood clots in people who are at high risk for their development. Treating blood clots that have already formed is managed by the use of anti-hemolytic ("clot busters"). Despite its effectiveness, the use of thromboprophylaxis remains under-utilized, though alerts (computer or human) in hospitals are associated with increased prescription and reductions in symptomatic VTE. The list below describes some of the more common medications used to prevent blood clots. Note that generally since blood clotting is inhibited, a side effect typically is increased bleeding, though it can be reversed by administering a medication that stops the bleeding or by discontinuation of the medication itself. Anti-coagulant administration is often given before the start of the operation. Medications that inhibit blood clot formation include:

Heparins

Adding heparin to the use of compression stockings may prevent thrombosis for those of higher risk. :::: The discontinuation of contraceptives also prevents blood clots.

Herbal interactions

The therapeutic effects of warfarin may be decreased by valerian. Anticoagulants can be affected by

chamomile Chamomile (American English) or camomile (British English; see spelling differences) ( or ) is the common name for several plants of the family Asteraceae. Two of the species, ''Matricaria recutita'' and ''Anthemis nobilis'', are commonly us ...

Dong quai ''Angelica sinensis'', commonly known as ''dong quai'' () or female ginseng, is a herb belonging to the family Apiaceae, indigenous to China. ''Angelica sinensis'' grows in cool high altitude mountains in East Asia. The yellowish brown root of th ...

, garlic, ginger,

Ginkgo biloba ''Ginkgo biloba'', commonly known as ginkgo or gingko ( ), also known as the maidenhair tree, is a species of tree native to China. It is the last living species in the order Ginkgoales, which first appeared over 290 million years ago. Fossil ...

bilberry Bilberries (), or sometimes European blueberries, are a primarily Eurasian species of low-growing shrubs in the genus ''Vaccinium'' (family Ericaceae), bearing edible, dark blue berries. The species most often referred to is '' Vaccinium myrtill ...

and feverfew can increase bleeding time. These same

herbal supplements Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedies ...

taken with warfarin increased

prothrombin time The prothrombin time (PT) – along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) – is an assay for evaluating the ''extrinsic'' pathway and common pathway of coagulation. This blood test is als ...

Dietary interactions

By containing significant content of

vitamin K Vitamin K refers to structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-synthesis modification of certain proteins that are required for blood coagulation ...

, some foods act as

antagonists An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, ri ...

to antiplatelet and anticoagulant medications; these include green leafy vegetables, like spinach, legumes, and

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cla ...

Contraindications

Preventing blood clots with medication is not considered safe in the following circumstances: * uncooperative patient * recent childbirth *

gastrointestinal bleeding Gastrointestinal bleeding (GI bleed), also called gastrointestinal hemorrhage (GIB), is all forms of bleeding in the gastrointestinal tract, from the mouth to the rectum. When there is significant blood loss over a short time, symptoms may include ...

reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are als ...

bleeding * genitourinary system
bleeding * hemorrhagic blood dyscrasias *

peptic ulcers Peptic ulcer disease (PUD) is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines i ...

alcoholism Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomi ...

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...

* eye surgery *

brain surgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and peri ...

* spinal cord surgery * recent cerebrovascular hemorrhage

Research

An international registry and risk assessment calculator is being used to centralize data on post-surgical venous thrombosis and its prevention. Hospitals are implementing a multi-disciplinary approach to prevent of blood clots. This includes adequate assessment of the risks, follow up on missed doses of medication and instituting a 'patient-centered' approach endorsed by the

Joint Commission The Joint Commission is a United States-based nonprofit tax-exempt 501(c) organization that accredits more than 22,000 US health care organizations and programs. The international branch accredits medical services from around the world. A majori ...

. Recommendations regarding the prevention of blood clots vary widely between clinicians and treatment facilities. Research continues to clarify these discrepancies. The metabolic state of hypercoagulability (the tendency to form blood clots) tests are being developed. These include the evaluation of the thrombin–antithrombin complexes (TAT), low levels of the anticoagulants ATIII and protein C, but these tests are not yet widely available.

References

Using Wikipedia for Research {{Prostanoidergics Preventive medicine Diseases of veins, lymphatic vessels and lymph nodes Coagulopathies Hematology Antiplatelet drugs Aspirin Blood Chemical substances for emergency medicine Nutrition Salicylates Tissues (biology)