Archive January 2018 XIX, No. 1

Catch DVT If You Can

Deep vein thrombosis is completely treatable if caught in time, but the symptoms aren't always easy to spot.

Joseph Caprini

Joseph Caprini, MD, MS, FACS, RVT


FATAL RISK When blood clots break off and travel to another part of the body, such as the lungs, it's called a pulmonary embolism — and it can be fatal.

Of all surgery's risks, developing blood clots of deep vein thrombosis (DVT) is one of the most dangerous — and one of the deadliest. It's also one of the most sinister. It's impossible to detect DVT about half of the time because there are no symptoms when a blood clot forms inside a vein, deep within the body very often in the thigh or lower leg. And when there are telltale signs of DVT, like shortness of breath, lung pain and chest pain, they often don't show up in patients until after you've discharged them. Of course, blood clots can break off and travel to another part of the body, such as the lungs. This is called a pulmonary embolism, or PE, and it can be fatal. PE claims the lives of up to 300,000 Americans every year.

The good news is that DVT is completely treatable if caught in time. It's also a largely preventable complication, as long as you identify which patients are most likely to develop it ahead of time. Once you have that information, you can decide on what prophylaxis — mechanical or anticoagulant or both — to administer and what precautions to take during surgery to cut down on the risk.

Precision medicine

My colleagues and I created a point-based scoring model to help facilities determine which surgical patients are most at risk of developing DVT and exactly what in their medical history leads them to be particularly vulnerable. The Caprini Risk Assessment includes 20 variables and is derived from a prospective study of 538 general surgery patients. The higher the Caprini score, the greater the risk of DVT.

Ask patients to compute their Caprini score 1-2 weeks before their procedure and instruct them to take their time filling out each question. That means sitting down with family members to ask about any family history of thrombosis, which is the most commonly missed question and, along with your patient's personal history of thrombosis, is one of the biggest causes of DVT. Don't try to give the assessment the day of surgery. There's a risk that patients will miss a question or answer it incorrectly because they haven't had the time to fully look it over. It's not reasonable to expect patients to know off the top of their head if their BMI is over 25, if they've had past obstetrical complications or if they had a venous thromboembolism (VTE) in the past but thought it not important — perhaps because it was caused by oral contraceptives that they're no longer taking.

Your patient's answers to those questions will give you an overall "Caprini score," which you can use on the day of surgery to stratify each patient's risk of DVT and, subsequently, what measures of prophylaxis you should provide. Patients with a score of under 5, who are classified as low-risk of developing DVT, may not need anticoagulant prophylaxis, whereas you should instruct patients with a score of 5-8, who are deemed at-risk of developing DVT, to take anticoagulants for 7-10 days following the surgery, even after they're discharged, or if they are outpatients. Classify patients who score a 9 or above as very high-risk and tell them to take a full 30 days of anticoagulant medication.

Precision medicine

Obtaining the score and understanding your patient's risk is only one part of preventing DVT. The key to cutting down on the rate of thrombosis cases is using that score to determine when and how you should administer thromboprophylaxis to your patient.

AT RISK Compression stockings help prevent thrombosis in at-risk patients.

Anticoagulants, such as low molecular weight or unfractionated heparin, can cost up to $500 for 30-day preventative doses, but studies have shown that they can reduce the risk of VTE in higher risk patients. One such study, published in the Current Opinion on Pulmonary Medicine, found the risk of a fatal pulmonary embolism reduced by 62% in patients who underwent prophylaxis with low-dose anticoagulants. The same study found the risk for symptomatic DVT reduced by 53%. However, there's still some debate surrounding the use of anticoagulant prophylaxis, due largely to concerns about patient bleeding. While it's true that anticoagulants can lead to bleeding, no one dies from receiving preventative doses of anticoagulants.

Risks of overtreatment

On the other hand, beware of the risk of overtreating. Three-fourths of surgical patients might be receiving anti-clotting medications they don't need, according to research my colleagues and I published in the Annals of Surgery. We concluded that the benefit of perioperative venous thromboembolism chemoprophylaxis was only found among surgical patients with Caprini scores ≥7. Precision medicine using individualized VTE risk stratification helps ensure that chemoprophylaxis is used only in appropriate surgical patients and may minimize bleeding complications.

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