What is the gold standard investigation of choice for deep vein thrombosis?
**Core Concept**
Compression ultrasonography (CUS) is the gold standard investigation for diagnosing deep vein thrombosis (DVT) due to its high sensitivity and specificity. It involves the use of ultrasound waves to compress the veins in the affected limb, and the absence of venous collapse indicates the presence of thrombosis.
**Why the Correct Answer is Right**
The correct answer is compression ultrasonography because it is non-invasive and can be performed at the bedside. It is particularly useful for diagnosing proximal DVT in the legs. The ultrasound waves are directed at the affected vein, and the absence of venous collapse suggests the presence of a thrombus. This is because the thrombus prevents the vein from collapsing when compressed by the ultrasound waves.
**Why Each Wrong Option is Incorrect**
* **Option A:** Magnetic Resonance Venography (MRV) is not the gold standard investigation for DVT. While it is a sensitive imaging modality, it is more expensive and less readily available than compression ultrasonography.
* **Option B:** D-dimer testing is not specific for DVT. Elevated D-dimer levels can be seen in various conditions, including malignancy, infection, and recent surgery, making it a non-specific test for DVT.
* **Option C:** Doppler ultrasound is not the gold standard investigation for DVT. While it can detect flow abnormalities, it is not as sensitive as compression ultrasonography for detecting thrombosis.
**Clinical Pearl / High-Yield Fact**
Remember that compression ultrasonography is the preferred initial test for DVT in patients with a high pre-test probability of DVT, such as those with recent surgery or trauma. This is because it is non-invasive and can be performed quickly, allowing for timely diagnosis and treatment.
**Correct Answer:** C.