What is the initial diagnostic test recommended for suspected deep venous thrombosis of the leg?

The initial diagnostic test recommended for suspected deep venous thrombosis (DVT) of the leg is a duplex ultrasound. This non-invasive imaging technique combines traditional ultrasound and Doppler ultrasound to visualize the veins and assess blood flow. It allows for the detection of thrombi in the deep veins of the leg with a high degree of accuracy, making it the preferred method for diagnosing DVT.

Duplex ultrasound is advantageous because it is widely available, requires no special preparation from the patient, and poses no risks associated with radiation or contrast media that other tests might involve. The real-time imaging ability of this test helps healthcare providers not only identify the presence of a thrombus but also evaluate its size and location, aiding in immediate clinical management decisions.

In contrast, while venography is considered a gold standard in some circumstances, it is more invasive and less commonly used due to the associated risks and lower availability. An arteriogram is primarily used to assess arterial diseases and is not relevant for diagnosing venous conditions like DVT. Impedance plethysmography is an outdated method with lower sensitivity and specificity than duplex ultrasound, making it less reliable for diagnosing DVT. Therefore, duplex ultrasound is the most effective and appropriate initial diagnostic test in this context.