Definition
A.Deep vein thrombosis (DVT) describes clot formation in the deep veins, most often in the lower extremities.
B.DVT increases the risk for venous thromboembolism (VTE) to the pulmonary circulation.
C.See Figure 12.2.
Incidence
A.More than 900,000 VTE events occur each year in the United States. Nearly one-third of these result in death.
B.Up to 50% of cases are believed to be idiopathic, with an additional 15% to 25% associated with cancer, and 20% associated with surgery.
C.Pulmonary embolism (PE) can occur in up to 50% of patients with untreated DVT.
D.The mortality rate associated with PE is 25% to 30%.
Pathogenesis
A.Three factors often referred to as Virchow’s triad promote venous thrombosis. These three factors are (a) venous stasis, (b) damage to venous endothelium, and (c) hypercoagulable states. Buildup of clotting factors and platelets promotes thrombus formation in the vessel, often adjacent to a valve. Inflammation associated with the clot promotes additional platelet aggregation, causing the clot to grow proximally.
B.Bed rest and/or immobility are factors often associated with venous stasis.
C.Hypercoagulability may be associated with increased activity of clotting factors or inherited or acquired conditions in which factors that would normally inhibit clotting are deficient.
D.Venous injury can result from surgery, trauma, and venous catheters.
E.Localized symptoms are the result of inflammation and venous obstruction, but symptoms may not be apparent if the vein is deep within the leg because of incomplete occlusion and collateral circulation.
FIGURE 12.2 Diagnosis of DVT.
DVT, deep vein thrombosis; PE, pulmonary embolism.
Predisposing Factors
A.Immobility.
B.Obesity.
C.Prolonged dependency (including air travel).
D.Age.
E.Heart failure.
F.Trauma.
G.Medications.
H.Malignancy.
I.Central venous catheters.
J.Pregnancy.
K.Oral contraceptives.
L.Hormone replacement.
M.Nephrotic syndrome.
N.Antiphospholipid antibody syndrome.
O.Hospitalization (especially orthopedic surgery, trauma, spinal cord injury, gynecologic disorders).
P.Inherited clotting disorders including Factor V Leiden mutation, prothrombin mutations, antithrombin deficiency, hyperhomocysteinemia, elevated Factor VIII activity, protein C deficiency, and protein S deficiency.
Subjective Data
A.Common complaints/symptoms.
1.Pain.
2.Swollen extremity.
3.Muscle tenderness.
B.Common/typical scenario.
1.Other signs and symptoms.
a.Fever.
b.Increased erythrocyte sedimentation rate.
c.Increased white blood cell count.
C.Family and social history.
1.History of recent surgery or trauma.
2.History of cancer, liver disease, autoimmune disorder, or cardiovascular disease.
3.Previous history of blood clotting or bleeding problems.
4.Family history of stroke or other thrombosis.
5.Immobility.
6.Recent prolonged travel.
D.Review of systems.
1.Musculoskeletal: Ask about extremity pain with or without movement, edema, and redness.
Physical Examination
A.Physical examination alone is less reliable than when coupled with thorough history.
B.Unexplained extremity swelling, pain, warmth, or erythema may be noted. Pain is frequently described as a cramp or ache in the calf or thigh.
C.The location of the thrombus may influence physical findings. Swelling in the foot and ankle and calf pain are associated with thrombi in the venous sinuses in the soleus muscle and posterior tibial and peroneal veins. Thrombi in the femoral vein are associated with pain in the popliteal area and distal thigh while those in the ileofemoral veins are manifested by pain and swelling involving the whole leg.
D.Upper extremity swelling along with pain and venous distention may indicate upper extremity DVT.
Diagnostic Tests
A.Serum D-dimer concentration.
B.Lower extremity ultrasonography.
C.CT.
D.MRI.
E.Venogram.
Differential Diagnosis
A.Trauma.
B.Infection.
C.Peripheral artery disease.
D.Chronic venous insufficiency.
E.Postthrombotic syndrome.
F.Lymphedema.
G.Erythema nodosum.
H.Insect bites.
I.Muscle strain.
Evaluation and Management Plan
A.General plan.
1.Prompt diagnosis of DVT is facilitated by combining medical history and physical examination, D-dimer testing, and appropriate use of imaging studies.
2.Hospitalized patients are typically treated with intravenous heparin and monitored for signs of bleeding.
3.Thrombolytic therapy should be reserved for massive PE or extensive DVT.
4.Contraindications to outpatient management of DVT include surgery within 7 days, cardiopulmonary instability, and severe symptomatic venous obstruction.
5.Additional contraindications for outpatient treatment include platelet count less than 50,000/lL, other medical or surgical conditions requiring inpatient management, medical nonadherence, geographical or telephone inaccessibility, impaired hepatic function, impaired renal function (e.g., rising serum creatinine), and inadequate home healthcare support.
6.The optimal duration of therapy is dictated by the presence of modifiable risk factors for thrombosis.
7.Long-term anticoagulation is an important consideration for individuals with unprovoked VTE or ongoing prothrombotic risk factors such as cancer and antiphospholipid antibody syndrome.
8.Short-term therapy is sufficient for most patients with VTE associated with transient triggers such as major surgery.
9.Inferior vena cava (IVC) filters should be considered for patients with acute VTE and contraindications to anticoagulation. Retrievable filters are preferable.
10.Warfarin is contraindicated in pregnancy while low molecular weight heparin (LMWH), dalteparin, and fondaparinux are pregnancy Category B.
B.Patient/family teaching points.
1.Patients must be taught to recognize concerning signs for bleeding diathesis while on anticoagulation.
2.Depending on the medication ordered, patients may need to have routine blood work completed.
3.Patients need to set reminders to take the medications the same time each day to optimize efficacy of the medication.
C.Pharmacotherapy.
1.Low dose fractionated or nonfractionated heparin given subcutaneously is the mainstay of treatment.
2.The availability of LMWH, fondaparinux, and direct oral anticoagulants (DOACs) has increased the options for acute outpatient treatment of DVT and PE.
a.DOACs can be as effective as LMWH and vitamin K antagonists such as warfarin.
D.Discharge instructions (If standard accepted guidelines exist please use discharge template).
1.Patients will need to follow-up with hematology as an outpatient.