From the Guidelines
Repeat ultrasound for deep vein thrombosis (DVT) is recommended within 5-7 days if clinical suspicion remains high despite a negative initial test, as suggested by the Society of Radiologists in Ultrasound Consensus Conference 1. This approach is supported by the latest guidelines, which emphasize the importance of considering ongoing symptoms, risk factors, and the comprehensiveness of the initial ultrasound when deciding whether to repeat testing. Key factors to consider when deciding whether to repeat a DVT test include:
- Persistent or worsening symptoms
- High-risk patients, such as those with recent surgery, immobility, cancer, or pregnancy
- Technically compromised initial study
- Concern for iliocaval DVT According to the SRU Consensus for DVT Ultrasound 1, a repeat scan is recommended in 5 days to 1 week if the initial complete duplex ultrasound is negative but clinical suspicion remains high. It is also important to note that anticoagulation before a confirmatory ultrasound is a safe strategy if ultrasound is not available, as mentioned in the guidelines 1. In contrast, an older study from the American College of Chest Physicians 1 suggests further testing with a moderate or highly sensitive D-dimer, serial US, or venographic-based imaging in patients with suspected upper extremity DVT and a high clinical suspicion, but this is not directly applicable to the current question about lower extremity DVT. Overall, the decision to repeat a DVT test should be based on a careful assessment of the patient's clinical presentation and risk factors, as well as the results of the initial ultrasound, with the goal of balancing the need to detect potentially dangerous clots with the risk of unnecessary testing.