Deep vein thrombosis: Clinical sciences

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Introduction0:00–0:46

Deep vein, thrombosis or DVT is a blood clot that develops in the deep veins. Most commonly of the lower limbs.
Less commonly. DVT can form in the deep veins of the arms or mesenteric veins of the bowel.
The pathogenesis of DVT centers around the Virchow triad, which includes venous stasis, hypercoagulability and endothelial injury.
If untreated, the thrombus can lead to limb ischemia, hemodynamic instability, pulmonary embolism and even death. Now, if your patient presents with signs and symptoms, suggestive of DVT.

Unstable patient0:46–1:24

First, you should perform an ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, stabilize the airway breathing and circulation.
Next, obtain IV access and start continuous vital sign monitoring including pulse, oximetry, BP and heart rate if needed.
Provide supplemental oxygen to maintain the oxygen saturation above 92%. All right.
Now, let's go back to the ABCDE assessment and discuss how to manage stable individuals. First obtain a focused history and physical examination history usually reveals pain, swelling and warmth in the affected limb as well as DVT risk factors such as age above 65.

Stable patient - History and physical examination1:24–3:09

Recent surgery, prolonged immobilization and active cancer as well as smoking and obesity. Also keep in mind that estrogen increases the risk of venous thrombosis.
So, pregnancy and the use of oral contraceptives are also important risk factors. Finally, a family history of DVT can indicate a familial inheritance of genetic conditions predisposing to DVT such as Factor Five Leiden mutation.
On the other hand, the physical examination usually reveals edema, erythema, warmth and tenderness of the affected area in some individuals.
You might even be able to palpate the thrombotic vein. Another important test is to see if you can elicit the Homan sign to do this, lift the affected leg and slightly bend it in the knee next abruptly and firmly perform dorsiflexion of the patient's foot.
The Homan sign is positive if dorsiflexion of the foot results in deep calf pain. But here's the thing, even though it's associated with DVT, the Homan sign is not sufficiently specific or sensitive to confirm the diagnosis because it's often positive in individuals without DVT.
At this point, you can suspect DVT. So at this point, your next step is to order labs including CBCD dimer and coagulation profile as well as renal and liver studies.

Labs3:09–3:21

Now, while you are waiting for lab results, use a validated metric such as the Wells criteria to predict the likelihood of DVT the WELLS criteria scores, historical findings, physical findings and alternative diagnoses.

Wells criteria3:21–4:28

Historical findings are worth one point and include a history of prior DVT, active cancer surgery or prolonged bedrest within three months or any recent condition that has weakened or immobilized.
The suspects limb like a splint. Physical features are also worth one point and they include localized pitting edema of the affected leg swelling of the entire lower limb calf circumference, asymmetry of three centimeters or greater in the affected leg, tenderness over a deep leg vein or collateral vein distension in the affected leg.
Finally, if you are considering alternative diagnoses like cellulitis or a ruptured baker cyst, then you'll subtract two points from the score.
Now, let's take a look at the wells score. If your patient scores two or more points, then there's a high likelihood of DVT.

Likely probability4:28–4:39

So you should order an ultrasound of the affected limb. On the other hand, if the score is below two, then there's a low likelihood of DVT.

Unlikely probability4:39–5:10

However, to really rule out a DVT, you should assess D dimer levels. If the D dimer is less than 500 nanograms per milliliter, you can consider an alternative diagnosis on the flip side if the D dimer is equal to or greater than 500 nanograms per milliliter.
Proceed with an ultrasound of the affected limb. All right.
Now that you have determined the patient's probability of DVT, let's take a look at the ultrasound, ultrasound of the affected limb is used to assess the condition of deep and superficial veins.

Ultrasound5:10–5:47

If the vein collapses under probe pressure, the finding is negative. So you should consider an alternative diagnosis on the flip side.
When there's a thrombus within the vein, the vein does not collapse. This means that the finding is positive which confirms the diagnosis of DVT.
Now, once you diagnose A DVT, the next step is to assess whether or not it's complicated, complicated DVT includes the presence of additional conditions such as pulmonary embolism and limb ischemia, but also pregnancy and malignancy.

Complicated DVT5:47–6:32

If your patient presents with any of these conditions, you may need to admit them to the hospital for further evaluation, closer monitoring and management such as anti coagulation, systemic or local thrombolysis and in some cases, mechanical thrombectomy.
On the other hand, if none of these are present, the patient has an uncomplicated DVT. These patients usually don't require hospitalization since these patients don't require hospitalization.

Contraindications to anticoagulation6:32–7:21

The next step is to assess contraindications to anti coagulation. If contraindications are present in your patient, such as a history of intracranial hemorrhage, recent gi bleeding or lab abnormalities like thrombocytopenia, then giving them anticoagulants might be too risky.
In this case, you should consult the interventional radiology team for inferior vena cava or IVC filter placement. This filter acts as a small cage that captures thrombus fragments and reduces the risk of pulmonary embolism.
Keep in mind that the IVC filter doesnt actually treat the DVT. So as soon as the contraindication to anti coagulation resolves its best to remove the filter and start anti coagulation.
Now, let's take a look at patients with no contraindications to anticoagulation. If contraindications are absent, treat your patient with anticoagulant medications which stabilize the thrombus and reduce the risk of fragmentation.

No contraindications to anticoagulation7:21–8:50

These include initial anticoagulation for 5 to 10 days with subcutaneous injection of low molecular weight heparins or LMWH like enoxaparin or IV unfractionated heparin followed by anticoagulation for 3 to 12 months with oral warfarin.
As an alternative, patients can get monotherapy with direct oral anticoagulants or doac for short, like Rivaroxaban without the need for initial anticoagulation with heparin.
Now, here's a high yield fact to keep in mind. DVT is considered provoked if it's associated with risk factors such as recent surgery or the use of oral contraceptives in these individuals, you should address their risk factor as soon as possible.
For example, you might need to discontinue oral contraceptives once you address the risk factor, continue anticoagulants for an additional three months.
On the other hand, DVT is considered unprovoked when you can't identify the underlying cause or when the cause is permanent.
For example, the patient might have an inherited thrombotic disorder. In this case, you should go with a long term sometimes lifelong anticoagulation therapy.
All right, as a quick recap, deep vein thrombosis or DVT is a condition that can result in life threatening complications such as pulmonary embolism.

Review8:50–10:25

So you need to diagnose it quickly. If your patient is unstable first, you need to stabilize them before you continue further evaluation.
On the other hand, if the patient is stable. Use the wells score to determine the probability of D VTA score of two or higher indicates a high likelihood of DVT.
So you should proceed with an ultrasound of the affected limb. On the flip side, a score below two refers to a low likelihood of DVT.
So your next step is to assess D dimer levels. D dimer levels of 500 nanograms per milliliter.
And above require an ultrasound. While below 500 nanograms per milliliter indicates an alternative diagnosis.
Next, negative ultrasound findings rule out DVT while positive findings confirm the diagnosis. Once you make the diagnosis, determine whether the DVT is complicated or uncomplicated.
Individuals with complicated DVT may require hospitalization while patients with uncomplicated DVT usually don't but should be assessed for contraindications to anti coagulation.
If contraindications to anticoagulation are present, proceed with an IVC filter. However, if there are no contraindications, start the anticoagulant therapy with LMWH or unfractionated heparin followed by Warfarin or Donax.