May-Thurner syndrome is an anatomical factor associated with increased DVT formation, and is characterized by which of the following?
Anatomic factors may also contribute to development of DVT. At the site where the right iliac artery crosses over the left iliac vein, the left iliac vein may become chronically narrowed predisposing to iliofemoral venous thrombosis, so-called MayThurner syndrome. External compression of major veins by masses of various types can also lead to venous thrombosis.
A Caprini score of ≥5 in a general surgery patient without thromboprophylaxis is associated with what percentage risk of developing a DVT?
Scoring systems have been developed that take into account the number of VTE risk factors in an individual patient. These risk stratification scores, such as the Rogers score and Caprini score, provide individual patient risk stratification and recommendations for prophylactic anticoagulation. The ninth edition of the American College of Chest Physicians (ACCP) Guidelines for Prevention of VTE in Non-Orthopedic Surgical Patients acknowledges both the Rogers and Caprini scores and provides recommendations for VTE. Orthopedic surgical patients are generally excluded from risk assessment scores because of the disproportionately increased risk of VTE in orthopedic surgery compared with the general and abdominopelvic surgery population.
Thromboembolism risk and recommended thromboprophylaxis in surgica l patients:
DVT = deep vein thrombosis; INR = international normalized ratio; LDUH = low-dose unfractionated heparin; LMWH = low molecular weight heparin; VTE = venous thromboembolism
Phlegmasia cerulea dolens is best described as:
Clinical symptoms may worsen as DVT propagates and involves the major proximal deep veins. Extensive DVT of the major axial deep venous channels of the lower extremity with relative sparing of collateral veins causes a condition called phlegmasia cerulea doZens (Fig. below). This condition is characterized by pain and pitting edema with associated cyanosis. When the thrombosis extends to the collateral veins, massive fluid sequestration and more significant edema ensue, resulting in a condition known as phlegmasia alba do lens. The affected extremity in phlegmasia alba do lens is extremely painful and edematous and pale secondary to arterial insufficiency from dramatically elevated below lower knee compartment pressures. Both phlegmasia cerulean dolens and phlegmasia alba dolens can be complicated by venous gangrene and the need for amputation.
Phlegmasia cerulea dolens of the left leg. Note the bluish discoloration
According to the American College of Chest Physicians, the recommended duration of long-term antithrombotic therapy after provoked DVT is:
The recommended duration of antithrombotic therapy is stratified based on whether the DVT was provoked or unprovoked, whether it was the first or a recurrent episode, where the DVT is located, and whether malignancy or thrombophilia is present. In patients with proximal DVT, several randomized clinical trials have demonstrated that shorter-term antithrombotic therapy ( 4 to 6 weeks) is associated with a higher rate ofVTE recurrence than 3 to 6 months of anticoagulation. In these trials, most of the patients with transient risk factors had a low rate of recurrent VTE, and most recurrences were in patients with continuing risk factors. The ACCP recommendation, therefore, is that 3 months of anticoagulation are sufficient to prevent recurrent VTE in patients with DVT occurring around the time of a transient risk factor (e.g., hospitalization, orthopedic or major general surgery).
Summary of American College of Chest Physicians recommendations regarding duration of long-term antithrombotic therapy for deep vein thrombosis (DVT):
LMWH = low molecular weight heparin; VKA = vitamin K antagonist.
All of the following are indications for placement of IVC filters EXCEPT:
Placement of an IVC filter is indicated for patients who have manifestations oflower extremity VTE and absolute con traindications to anticoagulation, those who have a bleeding complication from anticoagulation therapy of acute VTE, or those who develop recurrent DVT or PE despite adequate anticoagulation therapy and for patients with severe pulmonary hypertension.
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