DVT Flashcards
Lower Extremities DVT U/S Scan
Why do we perform?
How do we diagnose DVT on U/S?
- To rule out deep vein thrombosis in patients with lower extremity pain
- Patient in a supine position, head elevated about 30 degrees
- Use linear transducer and apply gel, starting at groin
- Ensure patient is covered appropriately
- At common femoral vein downwards, do full compression of the vein to obliterate the lumen. Move downwards releasing before each compression, down saphenous vein, popliteal vein
- Optimise image as you go along, changing depth
Alternative findings: Baker’s cyst
How does DVT form?
Deep veins lie between the muscles of the leg. Contractions in these muscles when we move our leg and ankle help to squeeze the blood back up to our heart. The vein also has valves that prevent backflow of blood down to the feet. DVT is when a blood clot/thrombus forms in the deep vein, where it partly or completely occludes flow in the deep vein. A large blood clot can cause pain and swelling in the affected leg, however DVT doesn’t always have symptoms.
What are the two types of venous thromboembolism (VTE)?
DVT and PE
Goals of treating DVT?
- Prevent death from PE
- Prevent post-thrombotic syndrome (restore vein patency and valvular function)
- Prevent recurrence
What is post-thrombotic syndrome?
DVT may develop long term symptoms like calf pain, swelling, rash, ulcers (severe case) in the calf known as PTS due to the valves being affected.
This affects around 20-40% of people with a history of DVT.
Proximal DVT (DVT in the thigh vein), obesity, and more than 1 DVT in the same leg increase the risk of PTS.
- Has a impact on cost of NHS
- Pressure stocking will reduce but patient compliance?
Evidence of thrombolysis
- Preserved endothelial fn and valve competence
- Clot resolution within 90 days protects valve competence
What is venography?
Outpatient x-ray examination that uses an injection of contrast material to show how blood flows through your veins. It is used to find blood clots. A radiologist will interpret results.
Cons - invasive, uses contrast (allergies, kidneys, could cause DVT) and is expensive
What are thrombolytic/fibrinolytic drugs?
Drugs used to dissolve blood clots
- alteplase
- streptokinase
- urokinase
How can thrombolysis be delivered?
Through a cannula into the vein or via catheter, delivered to the centre of the vein
Risks of thrombolysis
Excessive bleeding
What is the IVC filter treatment used for?
An IVC filter is a small metal device (grab) placed into the IVC which prevents a large pulmonary embolism by trapping a clot before it reaches the lungs. They are used in patients who don’t respond to or cannot be given conventional medical therapy such as blood thinners.
- Therapeutic: PE or DVT with contraindications for anticoagulation, massive PE with lingering DVT, or free floating thrombus
- Prophylactic: Severe trauma (head/spinal cord injury pts) or immobilised patients (ICU)
What are the two unequivocal indications for permanent IVC filter treatment?
- Recurrent PE on anticoagulation
- PE with contraindication to anticoagulation
- carefully selected because permanent filters thrombose 10% within 5yrs.
What are relative indications for permanent/ retrievable IVC filters?
- Severe cardiopulmonary disease with DVT (permanent)
- Free-floating iliofemoral or iVC thrombus (permanent or retrievable)
- Severe trauma (P or R)
- High risk patients (retrievable)
What are two relative contraindications for IVC filters?
- Uncorrectable severe coagulopathy
- Bacteremia or untreated infection
Where is the IVC filter placed and why?
Under the renal veins so if thrombus occurs, it spares the renal system
What is superficial thrombophlebitis?
Blood clots in the superficial veins?
What are blood clots in the superficial veins called? How are they treated?
Superficial thrombophlebitis
- Managed with non steroidal anti inflammatory drugs only no contraindications and compression hosiery
- Thrombolysis or blood thinners if near femoro-saphenous junction
What is Virchow’s Triad?
3 factors thought to contribute to thrombosis:
Endothelial injury (damages arising from trauma, shear stress or HTN)
Hypercoagulability (changes after trauma, cancer, late pregnancy and delivery, cigarette smoking, hormonal contraceptives, and obesity)
Stasis of blood flow (long surgical operations, prolonged immobility)
Signs and symptoms of DVT?
Swollen limb
fever
red limb
painful limb
warm limb
chest pain
superficial veins
Some people may show no symptoms and can have a silent dvt (not aware of it)
Remember DVT not jst limited to legs can occur in the arm too jus more common in the leg
Patient pathway DVT
-presents ED
-Wells Score performed - if likely, scan within 4hrs, if unlikely, do d-dimer - scan performed, seen in DVT clinic with results
Wells score unlikely - d-dimer performed, raised then refer for scan - scan performed, seen in DVT clinic
NICE 2020 guidelines
For people who present with signs or symptoms of DVT, such as a swollen or painful leg, assess their general medical history and do a physical examination to exclude other causes. [2012]
1.1.2
If DVT is suspected, use the 2‑level DVT Wells score (table 1) to estimate the clinical probability of DVT. [2012]
DVT likely (Wells score 2 points or more)
1.1.3
Offer people with a likely DVT Wells score (2 points or more):
a proximal leg vein ultrasound scan, with the result available within 4 hours if possible (if the scan result cannot be obtained within 4 hours follow recommendation 1.1.4)
a D‑dimer test if the scan result is negative. [2012]
1.1.4
If a proximal leg vein ultrasound scan result cannot be obtained within 4 hours, offer people with a DVT Wells score of 2 points or more:
a D‑dimer test, then
interim therapeutic anticoagulation (see the section on interim therapeutic anticoagulation for suspected DVT or PE) and
a proximal leg vein ultrasound scan with the result available within 24 hours. [2012, amended 2020]
1.1.5
For people with a positive proximal leg vein ultrasound scan:
offer or continue anticoagulation treatment (see the section on anticoagulation treatment for confirmed DVT or PE) or
if anticoagulation treatment is contraindicated, offer a mechanical intervention (see the section on mechanical interventions).
For people with a negative proximal leg vein ultrasound scan and a positive D‑dimer test result:
stop interim therapeutic anticoagulation, but do not stop:
long-term anticoagulation when used for secondary prevention [2012, amended 2020], or
short-term anticoagulation when used for primary venous thromboembolism (VTE) prevention in people with COVID‑19 (see the recommendations on VTE prophylaxis in the NICE guideline on managing COVID-19) [2023]
offer a repeat proximal leg vein ultrasound scan 6 to 8 days later and
if the repeat scan result is positive, follow the actions in recommendation 1.1.5 [2012, amended 2020]
if the repeat scan result is negative, follow the actions in recommendation 1.1.7. [2012, amended 2020]
NICE guidelines on interim anticoag
When using interim therapeutic anticoagulation for suspected proximal DVT or PE:
carry out baseline blood tests including full blood count, renal and hepatic function, prothrombin time (PT) and activated partial thromboplastin time (APTT)
do not wait for the results of baseline blood tests before starting anticoagulation treatment
review, and if necessary act on, the results of baseline blood tests within 24 hours of starting interim therapeutic anticoagulation. [2020]
Offer either apixaban or rivaroxaban to people with confirmed proximal DVT or PE (but see recommendations 1.3.11 to 1.3.20 for people with any of the clinical features listed in recommendation 1.3.7). If neither apixaban nor rivaroxaban is suitable offer:
LMWH for at least 5 days followed by dabigatran or edoxaban or
LMWH concurrently with a vitamin K antagonist (VKA) for at least 5 days, or until the international normalised ratio (INR) is at least 2.0 in 2 consecutive readings, followed by a VKA on its own. [2020]
What is a positive d-dimer
For DVT: <500ng/ml: Negative
> 500ng/ml:Positive
What is a d-dimer test used for?
D-dimer test – is a blood test that detects breakdown products of clotting in the bloodstream.
Normal D-dimer level for adults (<500 ug/L).
D-dimer is a product of fibrin disintegration and fibrin is found in clots.
If the D-dimer is elevated there is a clot somewhere in the body. However, the problem is that many other conditions like cancer, sepsis/infection, pregnancy, post-surgery can also have a high D-dimer.
It should take few hours (4) to return.
Therefore, you cannot use the D-dimer to diagnose a DVT. In statistics terms, the D-dimer has a high sensitivity and low specificity. If the D-dimer is low, no further testing is needed. But if the D-dimer is high, then proceed to doppler ultrasound of the affected lower extremity
What is a Wells score?
the pre test probability scoring system to determine the likelihood of a patent of a dvt >2 likely- referred for scan
Questions are related to sign/ symptoms and risk factors associated with a dvt.
Not reliable for pregnant ladies so not usually performed and referred directly for scan
Points on a two-level Wells score
Scoreonepoint for each of the following:
Active cancer (treatment ongoing, within the last 6months, or palliative).
Paralysis, paresis, or recent plaster immobilization of the legs.
Recently bedridden for 3days or more, or major surgery within the last 12weeks requiring general or local anaesthetics.
Localized tenderness along the distribution of the deep venous system (such as the back of the calf).
Entire leg is swollen.
Calf swelling by more than 3cm compared with the asymptomatic leg (measured 10cm below the tibial tuberosity).
Pitting oedema (greater than on the asymptomatic leg).
Collateral superficial veins (non-varicose).
Previously documented DVT.
Subtract twopoints if analternative causeis considered more likely than DVT.
What happens when a two-level Wells score is calculated?
The risk of DVT;
1 point or less – DVT unlikely, consider D-dimer
=/>2 = DVT likely, consider imaging
if likely the patient will be referred for a ultrasound scan to determine if positive if or not- NICE say this should be done within 4 hours but not always possible so are given interim AC till the next avaialbe scan slot
Cons to the NICE DVT protocol
Suggests proximal leg scan only (not calf veins)
If scan negative but d dimer positive then a repeat scan should be performed in 1 week
Some centre do a full leg scan at the first scan
A repeat scan is only required if the scan was inconclusive
DVT treatment options
Anticoagulation (LMWH (enoxaparin sodium) or DOAC e.g. apixaban, edoxaban etc) for at least three months
Renal impairment or bleeding risk – unfractionated heparin
Thrombolysis
Deep venous stenting
Compression hosiery – post thrombotic limb
Offer either apixaban or rivaroxaban for patients with a confirmed proximal DVT or PE (see below for guidance on specific population groups). If apixaban or rivaroxaban are unsuitable, offer either a:
low molecular weight heparin (LMWH) for at least 5 days followed by dabigatran etexilate or edoxaban; or
LMWH given concurrently with a vitamin K antagonist for at least 5 days or until the INR is at least 2.0 for 2 consecutive readings, followed by a vitamin K antagonist on its own.
What is venous incompetence?
Bicuspid one way valves cease to function properly
Blood flows towards and away from the heart (reflux)
>0.5seconds (mild)
>1.0seconds (moderate/severe)
Vaso vagal attack- If the vessels contain too much blood (augmentation of veins during venous assessment), the stretch receptors are activated and the heart rate reduces, the blood vessels dilate and blood pressure drops, this can cause the patient to faint.
Varicose vein treatment
Endovenous laser -A thin tube (a laser thread) is inserted into the vein through a small cut. The laser probe heats the vein from the inside, causing it to close. This is done with a local anaesthetic, which means the area to be treated is numbed so you won’t feel any pain. It takes about 45 minutes-1hour for this treatment on one leg.
Radio-frequency ablation - RFA is a procedure which closes the faulty superficial vein and leaves minimal scarring. A catheter will be placed into the faulty vein using an ultrasound scan for guidance. Once the catheter is in the correct position, a liquid containing local anaesthetic is injected around the vein. Radiofrequency energy is used to heat the catheter which applies direct heat to the vein wall causing it to shrink and seal.
Other varicose veins in your leg may be removed through small cuts (phlebectomies) or be injected with chemicals to close them (foam sclerotherapy).
Glue
Mechanical
High-Intensity Focused Ultrasound (HIFU)
Phlebectomy/avulsions - Phlebectomy is a minimally invasive procedure used to remove varicose veins that lie just beneath the skin’s surface. During the procedure, a vein specialist makes tiny incisions along the path of the varicose vein to extract it. This method is often preferred over traditional vein stripping due to its reduced recovery time and lower risk of complications. Patients can expect some discomfort, but it is generally well-tolerated, and recovery typically involves minimal downtime.
Foam (sclerotherapy)
Micro-sclerotherapy
Superficial Laser
Old Treatments: Stripping and High Tie
Pelvic Vein Incompetence and treatment
Chronic pelvic pain without gynaecological explanation
Predominately affects women with multiple pregnancies
50% of gyne laparoscopy patients have CPP
~2/3rds women with CPP have reflux
~1/3rd exhibit pelvic, vulval, perineal and upper thigh veins
Originate from incompetent ovarian or internal iliac veins
Treatment
Hormone therapy (Progesterone based)
Sclerotherapy/embolization – metal coil in pelvic veins to block blood flow
Ovarian vein ligation
Hysterectomy
Klippel-Trenauney Syndrome
Klippel-Trenaunay syndrome consists of three symptoms often seen together: port wine stains, varicose veins and limb hypertrophy.
98% capillary malformation (i.e. port-wine staining)
72% have severe varicosities
68% limb hypertrophy
19-45% bleeding and thrombo-phlebitis
Pain, Cellulitis, Lymphodema, Ulceration, Verrucae
What are things to make sure of when offering anticoag?
patient’s preference, comorbidities, contraindications: When starting treatment, carry out baseline blood tests (including full blood count, renal and hepatic function, prothrombin time and activated partial thromboplastin time).
What is percutaneous thrombectomy?
In this endovascular procedure, a catheter is inserted percutaneously into the peripheral
vasculature (usually via a common femoral vein) and advanced through the right side of
the heart into the pulmonary arteries under image guidance. This procedure is usually
performed by interventional radiologists and interventional cardiologists. It is usually
done using local anaesthesia with or without sedation
There are several thrombectomy devices available with some variation in their
mechanism. The thrombus may either be fragmented before removal or not. There are
several methods by which the thrombus can be removed: vacuum suction, aspiration
with a syringe, mechanical removal with a clot removal device or a combination of
methods.
