ULTRASOUND FOR DVT SURVEILLANCE
A major complication of surgery is a blood clot that develops in the legs, called a deep venous thrombosis, or DVT. The clot may break loose and travel to the lungs, where it can cause a pulmonary embolism.
The clot usually starts in the calf and then propagates upwards, getting larger. Once the clot reaches the deep veins in the thigh it is large enough to be dangerous. The problem is in identifying patients who are developing this problem. Leg swelling is not always reliable.
One approach is called risk stratification. A risk score is calculated based on the patient’s age, length of surgery, whether they are taking hormonal supplementation, their weight, etc. If a patient’s score (called a Caprini score) exceeds a certain threshold, then they are given blood thinners to help reduce the risk of a blood clot.
This method is appealing to many surgeons because it seems to make sense and prescribing a medication is easy. But like many easy and obvious solutions it is wrong.
First, this calculation is unreliable in determining who is at risk. The vast majority of patients who receive routine anticoagulation based on this score were never destined to develop a clot. Routine anticoagulation is not FDA-approved in healthy plastic surgery patients and the effectiveness is questionable at best. Recent evidence suggests the course of anticoagulation is too early and too short to make a difference. Plus, the bleeding risk is increased. So surgeons are doing very little to alter the risk of blood clots and at the same time increasing the risk of bleeding.
It turns out there is a better way, and that is ultrasound surveillance. This method helps remove the guesswork. Patients are scanned to detect blood clots. Those who show evidence of a blood clot are then given anticoagulation, typically for 3 months. This method avoids giving a potentially harmful medication to a patient who does not need it.
In addition to ultrasound surveillance, paralysis during surgery is avoided. This practice preserves the calf muscle pump. Devices that squeeze the calves during surgery are unnecessary.
Today it is hard to imagine a cardiologist working without the benefit of an EKG. It is just as difficult to imagine any serious effort at reducing DVT risk that does not include screening patients for these clots, which might otherwise develop undetected.
Ultrasound surveillance replaces ineffective methods that try to predict affected patients and avoids prescribing medications that may cause unnecessary bleeding after surgery. It is highly accurate, noninvasive, and well-tolerated by patients, who do not pay extra for this service.
- Swanson E. The case against chemoprophylaxis for venous thromboembolism prevention and the rationale for SAFE anesthesia. Plast Reconstr Surg Glob Open 2014;2:e160.
- Swanson E. Why risk assessment models are ineffective in predicting venous thromboembolism in plastic surgery patients. Aesthet Surg J. 2016;36:NP233–NP234.
- Swanson E. Prospective study of Doppler ultrasound surveillance for deep venous thromboses in 1000 plastic surgery outpatients. Plast Reconstr Surg. 2020;145:85–96.
- Swanson E. Reconsidering the role of routine anticoagulation for venous thromboembolism (VTE) prevention in plastic surgery. Ann Plast Surg. 2020;85:97–99.