Risk Factors
List a condition that DVT is a risk factor for.
Pulmonary Embolism
What is the General incidence of DVT in Australia?
0.52 per 1000 people per year
A 46-year-old woman develops unilateral lower-leg swelling and erythema after spending the weekend gardening. The area is mildly warm and very itchy, but she is afebrile and otherwise well. The swelling developed within several hours.
allergic reaction
What is the cause of visible superficial veins vs pitting edema in DVT.
Superficial veins: back flow into veins as collateral venous flow. Pitting edema: raised pressure in capillaries causing fluid to leek out
Why are flights a risk factor for DVT?
Blood stasis (and dehydration to a lesser extent)
What is the rate of recorded postoperative dvt following hip or knee replacements?
635 per 100,000 hospitalisations
A 71-year-old man presents with a swollen, warm, erythematous left calf. He has a superficial abrasion over the shin but no fever. The calf is diffusely swollen and the discomfort feels deep rather than confined to the red skin. He was discharged 5 days ago after abdominal surgery.
DVT (Deep, throbbing ache or cramp like pain)
Cellulitis (Sharp, tender surface pain when touched)
The abrasion is deliberately distracting because it could suggest cellulitis. However, recent surgery, diffuse unilateral swelling, and deep calf discomfort increase the likelihood of DVT. Cellulitis usually causes more prominent superficial skin tenderness around an expanding area of erythema.
You feel the legs of one patient with DVT and one patient with an arterial embolism. What are the temperatures and colours of their legs? Why?
DVT: warm and red or reddish-purple. Arterial embolism: Cold and pale.
Name 3 factors that increase the risk of developing DVT, at least two of which must be at minimum moderate risk factors.
Long periods of immobilisation, surgery, vein injury, clotting disorders, heart failure, IBD, personal/family history, increased oestrogen, pregnancy, obesity, age, smoking
What was the approximate reduction in Australia's recorded postoperative DVT rate after hip or knee replacement between 2011 and 2020?
Roughly a 47% reduction
A patient presents with a red, swollen lower leg after noticing an insect bite the previous day. The area has increased in size over 24 hours and is warm to touch. Which feature would most strongly suggest that this is cellulitis rather than a large local bite reaction?
pain and tenderness becoming more prominent than itching.
Both cellulitis and large local bite reactions can become red, warm, swollen and quite large, so those features alone do not distinguish them well.
A local allergic reaction is usually dominated by itching, whereas cellulitis is more likely to cause progressively increasing pain and skin tenderness. Fever or systemic symptoms would provide even stronger support for infection.
What is a silent DVT and how common is it?
Up to half are silent (have no specific symptoms like pain or swelling).
Which 2 of the following are NOT risk factors for DVT? Malignancy, haemophilia a, arthroplasty, pregnancy, Vow Willebrand disease
Haemophilia a and Von Willebrand disease
What was the incidence of hospital-acquired VTE per 1,000 patients?
11.45 per 1000 patients
A 34-year-old man develops a large red swollen area over his forearm after an insect bite. 24 hours later, the area is larger and warm. He has no fever, no and says the lesion is still much itchier than painful. Which diagnosis remains more likely despite the increasing size?
Local allergic reaction!
Increasing size does not automatically mean cellulitis.
Large local insect reactions can continue enlarging for 1-2 days. The continued predominance of itch over pain, lack of systemic symptoms, and clear bite history favour an inflammatory reaction.
Homan’s sign: with knee extended and leg raised to 10 degrees, sharply dorsiflex the ankle. Explain.
Stretches calf muscles, puts tension on the vein and irritated tissue and causes pain.
Name all 3 components of Virchow’s Triad, and name a risk factor that satisfies ALL components.
Stasis, hypercoagulability, endothelial damage: surgery or pregnancy
Post Surgery complication rate of PE compared to DVT
In Australia's 2020 data, this complication had a postoperative rate of 556 per 100,000 following hip or knee replacement, compared with 635 per 100,000 for DVT.
A 63-year-old woman presents with unilateral leg swelling, erythema and warmth. She has no fever and no obvious skin wound. The leg is tender, but the tenderness is mainly in the calf rather than the skin. She has active malignancy and started chemotherapy 2 weeks ago. Her Wells score suggests DVT is likely. What is the next most appropriate diagnostic step?
ultrasound!
At higher difficulty, the distinction is not just recognising DVT but knowing what to do next. With a likely pre-test probability, DVT needs objective confirmation, typically with compression ultrasound, depending on the diagnostic pathway used locally.
What is phlegmasia cerulea dolens?
Massive venous thrombosis that blocks the entire venous blood flow out of the limb- blocks both deep and collateral venous systems. High mortality rate and high risk of amputation.