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robbin 9th edition (editting according to 10th edition)

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-indirect thrombin inhibitor

-LMWH

-Heparin inhibits coagulation of binding to inactive antihrombin III

-cause conformational change

-potentiate activity of antithrombin III

-active antithrombin III binds & inhibits factor xa

-lead to inhibition of conversion of prothrombin to thrombin

-inhibit conversion of fibrinogen to fibrin formation

-to prevent further clot formation in plasma

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-vitamin K epoxide reductase inhibitor

-inhibit vit K epoxide reductase component

-inhibit the reduction of vit K epoxide

-to active hydroquinone which subsequently inactive factor II, VII, IX, X

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GCS apply graduated pressure to the legs, being tighter at the ankle and gradually looser towards the knee or thigh. This design promotes blood flow back to the heart, reducing venous stasis and the likelihood of clot formation. They are especially beneficial for patients who are immobilised due to surgery or medical conditions.

Must be avoided in people who have severe edema, leg deformities and peripheral arterial disease.

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Lack of physical activity

-high body mass index (BMI )

-need at least 150 minutes of aerobic activity a week

Eating food high in calories

-food high in sugar (lead to accumulation of fat in adipose tissue)

-food high in saturated fat (can lead to fat accumulation in blood vessels)

Not getting enough good-quality sleep

-affect hormones that control hunger urges

- make us overeat or not recognize our body’s signals that we are full.

High amounts of stress

-can affect the brain and trigger your body to make hormones,such as cortisol, that control energy balances and hunger urges.

-these hormones changes can make you eat more and store more fat

Health conditions

- metabolic syndrome and polycystic ovary syndrome cause people to gain weight

-genetic (researchers have found at least 15 genes that influence obesity. Studies show that genetics may play a more important role in people with obesity than in people who are overweight)

Medicines

-cause weight gain by distrusting the chemical signals that tell your brain you are hungry. These include:

antidepressants

Antipsychotics

Beta-blockers

Birth Control

Glucocorticoids

Insulin

Environment

-live, work, home, buildings in which you work or shop, streets and open spaces

-people living in neighbourhoods with more fast food restaurants are more likely to be overweight or obese

Causes and risk factors | NHLBI, NIH. (2022, March 24). NHLBI, NIH. https://www.nhlbi.nih.gov/health/overweight-and-obesity/causes

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Thrombi in legs tend to produce few reliable signs or symptoms.

Symptoms:

i) distal edema

ii) cyanosis - when your skin, lips and/or nails turn a bluish tone due to lack of oxygen in your blood

iii) superficial vein dilation

iv) heat

v) tenderness

vi) redness

vii) swelling

iix) pain

What is Homan Sign?

A clinical finding of pain behind the knee upon forced dorsiflexion of the foot. It has been traditionally performed as part of the physical examination in individuals with suspected deep vein thrombosis (DVT) of the lower extremity. Flexion of the knee and forced dorsiflexion of the ankle causes traction on the posterior tibial vein, resulting in pain behind the knee.

What does a positive Homan Sign mean?

For many years, a positive Homan Sign was thought to be a clinical sign of deep vein thrombosis of the lower extremity, however, evidence shows that not all individuals with DVT exhibit a positive Homan sign at evaluation.

Hernandez A. (2025, Jan 07). Homan Sign. Osmosis from Elsevier.

https://www.osmosis.org/answers/homan-sign

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Estrogen-containing birth control pills can cause water retention, which may show up swelling in the legs or ankles.

Estrogen can raise your risk of a blood clot in your legs called a deep vein thrombosis (DVT). In addition to swelling, you may notice pain, redness and warmth with a DVT.

https://www.goodrx.com/drugs/side-effects/these-7-medications-can-cause-puffy-legs-and-ankles#:~:text=6.-,Birth%20control%20pills,up%20in%20a%20similar%20way.

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1. D-dimer is a fibrin degradation product whose elevation signals active clot formation and fibrinolysis. The ACCP guidelines recommend combining a validated clinical pretest probability score with D‑dimer measurement to rule out DVT in low- to intermediate-risk patients, thereby avoiding unnecessary imaging

2. A Complete Blood Count (CBC) evaluates for anemia, infection, or thrombocytopenia. Platelet count is critical before administering heparin, as a baseline is needed to detect HIT. ESR and other inflammatory markers help exclude alternative causes of limb swelling or pain, such as infection.

3. Establishing baseline PT, aPTT, and INR ensures that initial anticoagulant dosing can be tailored safely, minimizing bleeding risk.

Reference

1. https://academic.oup.com/jalm/article-abstract/3/5/870/5603115

2. https://pubmed.ncbi.nlm.nih.gov/31639762/

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Venous Thromboembolism: Role of the Clinical Laboratory in Diagnosis and Management

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AbstractBackground. Venous thromboembolism (VTE) is the third most common cause of cardiovascular illness and is projected to double in incidence by 2050.

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especially regarding endothelial injury

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-increase capillary hydrostatic pressure

-decrease plasma colloid osmotic pressure

What causes a swelling / oedema?

1)heart failure

-heart fail to pump blood normally from vein into the artery

-raised venous & capillary pressure cause increase capillary filtration

2)decreased kidney excretion of salt & water

-most sodium chloride added to the blood remains in the extracellular compartment & only a small amount enters the cell

Guyton & hall textbook

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Smoking > Endothelial damage > Thrombosis > Affect blood flow and clot

Blood clotting : Toxic chemicals change platelets, making them sticky and prone to clumping and clotting, even when there is no injury. Nicotine also increases the number of platelets > more sticky platelets > clots develop at faster rate > amplifies effect of slow and thickened blood flow > increase the risk of DVT

https://www.memphisvein.com/blog/smoking-is-a-major-dvt-risk-factor-heres-what-you-should-know

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Smoking is a Major DVT Risk Factor: Here's What You Should Know

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Smoking causes many life-threatening conditions. But did you know that it's also a major risk factor for deep vein thrombosis, a blood clot that can turn dead

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Reverse Trendelenburg position

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What is Doppler Ultrasound and its Usage?

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Immobilization can lead to stasis of the blood

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Immobilization can lead to stasis of the blood

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Stasis of the blood occurs when blood flow becomes slow and turbulent, forming static pockets of blood. It is one of the primary abnormalities from the Virchow triad that leads to intravascular thrombosis. When blood flow is reduced, it reduces the venous return to the heart and increases the chances of blood clot formation.

Kumar, V., Abbas, A. K., & Aster, J. C. (2018). Robbins Basic Pathology (10th Edition). Elsevier Inc.

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https://youtu.be/xeSzzw13fbw?si=QVXswDu3OmhgAJva

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Venous Stasis

decreased blood flow

normally, muscle contraction helps pump venous blood back to the heart

due to immobilization, milking action of the leg muscle is reduced

resulting in stasis

Endothelial Dysfunction

prolonged immobilization leads to local vessel wall injury

due to pressure & hypoxia

damaged endothelium can contributes to clot formation

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In obesity patients, there is elevated levels of plasminogen activator inhibitor-1 (PAI-1).

PAI-1 inhibits tissue plasminogen activator (tPA), a key enzyme responsible for clot breakdown.

In obese individuals, especially those with excess visceral fat, adipose tissue produces more PAI-1, leading to reduced fibrinolytic activity.

This impaired fibrinolysis increases the risk of thrombotic events such as deep vein thrombosis (DVT). ​

Additionally, insulin resistance further contributes to elevated PAI-1 levels, leading to impairment of fibrinolysis. ​

https://pubmed.ncbi.nlm.nih.gov/15356668/

https://www.sciencedirect.com/science/article/pii/S1538783622151007?utm_source=chatgpt.com

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To determine the pretest probability of DVT, Wells score is use.

A Wells score is calculated with patients scoring +1 point for each of the below criteria:

active cancer (ongoing treatment/ treatment within last 6 months, or palliative)

paralysis, paresis, or recent plaster immobilisation of the legs

recently bedridden for ≥3 days, or major surgery within the last 12 weeks requiring general or local anaesthetics

localised tenderness along the distribution of the deep venous system

entire leg swelling

calf swelling >3 cm compared with the asymptomatic leg (measured at 10 cm below the tibial tuberosity)

pitting oedema (greater than on the asymptomatic leg)

collateral superficial veins (non-varicose)

previously documented DVT

Two points are subtracted if an alternative diagnosis is more likely than DVT (e.g. muscular tear, cellulitis, etc.).

DVT is considered likely in patients with a Wells score of 2 or above and unlikely in patients with a score of less than 2.