Thrombosis prevention or thromboprophylaxis is

medical treatment A therapy or medical treatment is the attempted remediation of a health problem, usually following a medical diagnosis. Both words, ''treatment'' and ''therapy'', are often abbreviated tx, Tx, or Tx. As a rule, each therapy has indications an ...

to prevent the development of

thrombosis Thrombosis () is the formation of a Thrombus, 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 (thrombocytes) and fib ...

(

blood clot A thrombus ( thrombi) is a solid or semisolid aggregate from constituents of the blood (platelets, fibrin, red blood cells, white blood cells) within the circulatory system during life. A blood clot is the final product of the blood coagulatio ...

s inside

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

s) 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 environ ...

for the formation of blood clots than others, such as those with

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

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 Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethr ...

. 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 Thrombosis prevention, blood clots and, in the treatment of venous thromboembolism (deep vein thrombosis and pulmonary embolism), and ...

(LMWH) was superior to unfractionated

heparin Heparin, also known as unfractionated heparin (UFH), is a medication and naturally occurring glycosaminoglycan. Heparin is a blood anticoagulant that increases the activity of antithrombin. It is used in the treatment of myocardial infarction, ...

in the initial treatment of

venous thromboembolism Venous thrombosis is the 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 lun ...

for people with cancer. There are medication-based interventions and non-medication-based interventions. The risk of developing blood clots can be lowered by lifestyle 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. The introduction of the birth control pill ("the Pill") in 1960 revolutionized the options for contraception, ...

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 conn ...

. In those at high risk, both interventions are often used. The treatments to prevent the formation of blood clots are balanced against the risk of bleeding. One of the goals of blood clot prevention is to limit venous stasis as this is a significant risk factor for forming blood clots in the deep veins 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 In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart ...

to cause blockage and subsequent tissue death in other

organs In a multicellular organism, 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 a ...

. Clarence Crafoord 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 use ...

s, and other interventions. Some risk factors can be modified. These would be losing weight, increasing exercise, and the cessation of

s. Moving during periods of travel is a modifiable behavior. Preventing blood clots includes medications that interrupt the complex clotting cascade and changing the proteins needed for clotting.

Antiplatelet An antiplatelet drug (antiaggregant), also known as a platelet agglutination inhibitor or platelet aggregation inhibitor, is a member of a class of pharmaceuticals that decrease platelet aggregation and inhibit thrombus formation. They are effectiv ...

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 enl ...

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 *

ectopic pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these sympto ...

* molar pregnancy * pregnancy * childbirth and the puerperium * coronary *

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 *

pulmonary The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

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, administ ...

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 specialty (medicine), medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system ...

* 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, e ...

* 45% for 60% in

orthopedic surgery Orthopedic surgery or orthopedics ( alternative spelling 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 than others. One scoring system analyzes the probability of 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 utilize the Well's test. It has been inconsistently modified by several 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 institutes, national public health agency of the United States. It is a Federal agencies of the United States, United States federal agency under the United S ...

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 venous stasis.

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

activation may result from an interaction between cabin conditions (such as hypobaric hypoxia) and individual risk factors for the formation of blood clots. Studies of the pathophysiologic mechanisms for the increased risk of

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 to prevent thrombosis and are beneficial enough to be used by 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 inflate and deflate 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 through an early risk assessment upon hospital admission, 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 of 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 can then apply protocols for prevention based on 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 prevent immobility and shift 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 a 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 closed chair. Patient education and compliance reduce the risk of developing blood clots. These exercises and the use of equipment and follow-up by clinicians reduce the risk of developing blood clots. If a blood clot has already formed in the deep veins of the leg, early movement out of bed is usually prescribed, except in some severe cases of deep vein thrombosis or in people who have

phlegmasia cerulea dolens Phlegmasia cerulea dolens (PCD) (literally: 'painful blue inflammation'), not to be confused with preceding phlegmasia alba dolens, is an uncommon severe form of lower extremity deep venous thrombosis (DVT) that obstructs blood outflow from a vein ...

. The treatment to prevent blood with physical intervention (e.g., sequential compression device) is contraindicated.

Medication

Anticoagulants and antiplatelets

Thromboprophylaxis, such as

anticoagulant An anticoagulant, commonly known as a blood thinner, is a chemical substance that prevents or reduces the coagulation of blood, prolonging the clotting time. Some occur naturally in blood-eating animals, such as leeches and mosquitoes, which ...

s 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 at higher risk. :::: The discontinuation of contraceptives also prevents blood clots.

Herbal interactions

The therapeutic effects of warfarin may be decreased by valerian.

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 chamomilla'' and '' Chamaemelum nobile'', are commo ...

can affect the action of anticoagulants.

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

, garlic,

ginger Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice and a folk medicine. It is an herbaceous perennial that grows annual pseudostems (false stems made of the rolled bases of l ...

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

bilberry Bilberries () are Eurasian low-growing shrubs in the genus ''Vaccinium'' in the flowering plant family Ericaceae that bear edible, dark blue berries. They resemble but are distinct from North American blueberries. The species most often referre ...

, and feverfew can increase bleeding time. These same herbal supplements 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 Coagulation#Extrinsic pathway, extrinsic pathway and Coagulation#Common pathway, ...

Dietary interactions

By containing significant content of

vitamin K Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-translational modification, post-synthesis modification of certain proteins ...

, some foods act as

antagonists An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain.spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to Central Asia, Central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common vegetable consumed eit ...

legumes Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consu ...

, and

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the Brassicaceae, cabbage family (family Brassicaceae, genus ''Brassica'') whose large Pseudanthium, flowering head, plant stem, stalk and small associated leafy gre ...

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 includ ...

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 al ...

bleeding *

genitourinary system The genitourinary system, or urogenital system, are the sex organs of the reproductive system and the organs of the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the u ...

bleeding * hemorrhagic blood

dyscrasia In medicine, both ancient and modern, a dyscrasia is any of various disorders. The word has ancient Greek roots meaning "bad mixture". The concept of dyscrasia was developed by the Greek physician Galen (129–216 AD), who elaborated a model of ...

s *

peptic ulcers Peptic ulcer disease is when the inner part of the stomach's gastric mucosa (lining of the stomach), the first part of the small intestine, or sometimes the lower esophagus, gets damaged. An ulcer in the stomach is called a gastric ulcer, while ...

alcohol use disorder Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World Hea ...

* infection *

eye surgery Eye surgery, also known as ophthalmic surgery or ocular surgery, is surgery performed on the eye or its adnexa. Eye surgery is part of ophthalmology and is performed by an ophthalmologist or eye surgeon. The eye is a fragile organ, and require ...

brain surgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system including the brain, s ...

* spinal cord surgery * recent

intracranial hemorrhage Intracranial hemorrhage (ICH) refers to any form of Hemorrhage, bleeding Internal bleeding, within the Human skull, skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized ...

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

multidisciplinary approach An academic discipline or academic field is a subdivision of knowledge that is taught and researched at the college or university level. Disciplines are defined (in part) and recognized by the academic journals in which research is published, a ...

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)