Thrombosis, Deep Vein (DVT)

By admin On Nov 15, 2023

Ovid: 5-Minute Sports Medicine Consult, The

Harry Stafford

Blake Boggess

Jake Veigel

Basics

Description

Venous thrombosis is a condition in which a blood clot (thrombus) forms in a vein.
This clot can limit blood flow through the vein, causing swelling and pain.
Most commonly, venous thrombosis occurs in the “deep veins” in the legs, thighs, or pelvis.
Associated with inflammation of the vessel wall
This is called a deep vein thrombosis, or DVT.
Roughly 2 million cases of thrombophlebitis occur in the U.S. annually.
Most significant complication is pulmonary embolism (PE), from which an estimated 60,000 Americans die annually
Lower extremity DVT is divided into distal (to the popliteal vein) or proximal.
DVT can also occur in upper extremity veins.

Epidemiology

Venous thrombosis can form anywhere in the venous system. However, DVT is the most common type of venous thrombosis. If a part or all of the blood clot in the vein breaks off from the site where it was created, it can travel through the venous system; this is called an embolus.
If the embolus lodges in the lung, it is called a pulmonary embolism (PE).
In most cases, PE is caused by a DVT when part of a blood clot breaks off and lodges in the lung.

Incidence

Affects ∼1 in 1,000 people every year. Rates increase with age and are higher in males compared to females.

Prevalence

∼2 million cases of deep venous thrombosis occur in the U.S. annually.

Risk Factors

Independent risk factors (1):
- Increasing age
- Surgery
- Trauma: Fractures of long bones or crush injuries
- Hospitalization or nursing home confinement
- Malignancy
- Indwelling or prior indwelling central venous catheter or pacemaker
- Prior superficial vein thrombosis
- Neurologic disease with paresis
- Liver disease
Other risk factors:
- Oral contraceptive use
- Pregnancy/postpartum period
- Hormone replacement therapy
- Tamoxifen therapy
- Selective estrogen receptor modulator therapy
- Travel
- Inherited hypercoagulable states
- Other hypercoagulable states
- High altitude (>14,000 feet)
- Prior DVT or pulmonary embolism
- Obesity
- Nephrotic syndrome
- Heparin-induced thrombocytopenia
- Polycythemia vera
- Myeloproliferative disorders
- Disseminated intravascular coagulation
- Paroxysmal nocturnal hemoglobinuria
- Thromboangiitis obliterans
- Thrombotic thrombocytopenic purpura
- Behçet disease
- Systemic lupus erythematosus
- Inflammatory bowel disease

Genetics

Genetic defects such as factor V Leiden mutation or protein C or S deficiencies are associated with DVTs.

General Prevention

Avoid prolonged immobility.
Caution when using birth control; use low-estrogen pills when possible.
Prophylaxis for hospitalized patients

Etiology

Virchow's triad of venous stasis, vessel wall injury, and coagulation abnormality is considered the primary mechanism for the development of venous thrombosis.

Commonly Associated Conditions

Malignancy accounts for 1/5 of all cases.
The list of risk factors is inclusive of associated conditions.

Diagnosis

Wells criteria (2)[A]

Active cancer within 6 mos	+1
Paralysis or immobilization of lower extremity	+1
Recent bedridden >3 or surgery	<4 wks +1
Tenderness/cord along vein	+1
Entire leg swollen	+1
Calf circumference >3 cm vs other leg	+1
Alternative diagnosis likely	-2
Interpretation
High probability	+3
Moderate probability	+1–2
Low probability	0

History

Many patients are asymptomatic; however, the classic symptoms are swelling, pain, and discoloration in the involved extremity.
Clinical signs and symptoms of PE as the primary manifestation occur in 10% of patients with confirmed DVT.
The pain and tenderness associated with DVT do not usually correlate with the size, location, or extent of the thrombus.

Physical Exam

Inspection of the extremity may reveal ipsilateral edema, erythema:
- >1–2-cm circumferential difference in leg
Palpation of the extremity may reveal a palpable cord, increased warmth, and superficial venous dilation.
Homans' sign: Passive dorsiflexion of the ankle elicits pain in the calf.
Phlegmasia cerulean dolens: Reddish purple lower extremity from venous engorgement and obstruction
Evaluate for signs of pulmonary embolus: Tachycardia, tachypnea, low-grade fever, and a cardiac exam

Diagnostic Tests & Interpretation

Duplex scanning (combination of color Doppler and B-mode US):
- Rapid, inexpensive, and highly accurate in detecting proximal DVT
Impedance plethysmography:
- Nearly as accurate as duplex scanning
- Not as routinely available as US
Venography is the historic gold standard:
- Accurate but invasive
- Associated with dye reactions
- Can precipitate phlebitis

Lab

No blood test diagnoses or excludes DVT with certainty:
- D-dimer (ELISA technique) has sensitivities around 95% (3)[A].
All D-dimer assays have been evaluated in various validation studies that determine the assay's sensitivity, specificity, and negative predictive value (NPV). An assay with a sensitivity of 80% has an NPV of 97.6% in a low-risk patient. However, the NPV of the same assay is only 33% in high-risk patients with a pretest probability of 90% for DVT.
CBC and prothrombin time (PT)/partial thromboplastin time (PTT) as baseline measurements
Labs for idiopathic DVT include factor V Leiden, prothrombin, serum homocysteine, factor VIII level, lupus anticoagulant, protein C and S levels, antithrombin activity, and anticardiolipin antibodies.

Imaging

US (3)[A]:
- Sensitivities and specificities vary by vein with more accuracy in the proximal veins.
- Sensitivities of 89–96%
- Specificities of 94–99%
- US is recommended for patients with high pretest probability (Wells criteria) in the lower extremities (4)[A].
Helical CT scan

Diagnostic Procedures/Surgery

Contrast venography has long been considered the reference test for the diagnosis of DVT.

P.591

Differential Diagnosis

Superficial thrombophlebitis
Cellulitis
Torn muscles and ligaments
Ruptured baker's cyst
Bilateral edema (seen with heart, kidney, or liver disease) is rarely caused by DVT.
Prior DVT and postphlebitic syndrome
Arterial insufficiency
Arthritis
Cellulitis, lymphangitis
Extrinsic compression of iliac vein secondary to tumor, hematoma, or abscess
Hematoma
Lymphedema
Neurogenic pain
Prolonged immobilization or limb paralysis
Stress fractures or other bony lesions
Varicose veins

Treatment

ED Treatment

Anticoagulation:
- Contraindications:
  - Active internal bleeding
  - Uncontrolled HTN
  - Significant recent trauma or surgery
  - CNS tumor
  - Initiate in the emergency department
- Duration of oral anticoagulation in unprovoked venous thromboembolism should be extended (longer than 12 mos, level 1 evidence), whereas provoked venous thromboembolism may be well served with just 3 mos of therapy (level 2 evidence) (5).
- Recurrent thromboembolism despite documented adequate anticoagulation (defined as an aPTT of <1.5 times control for heparinized patients and an international normalized ratio (INR) of <2 for warfarinized patients) requires vena caval interruption.
Low molecular-weight heparin (LMWH) is treatment of choice if cost is less important or outpatient management is considered:
- Enoxaparin
- Does not require laboratory monitoring
- May be administered as an outpatient
- Initiate oral warfarin therapy same day

Medication

Enoxaparin: 1 mg/kg SC b.i.d.
Heparin: 80 IU/kg bolus followed by a drip of 18 IU/kg/hr (aPTT should be checked in 6 hr and tile infusion rate adjusted accordingly)
Warfarin: 10 mg PO, then 5 mg PO every day; monitor PT

Additional Treatment

Referral

Cardiology, pulmonary, or anticoagulation clinic is appropriate if the physician is unable to monitor the INR levels or is uncomfortable with managing patients with DVT.

In-Patient Considerations

Initial Stabilization

Patients with DVT rarely require immediate stabilization:

Phlegmasia alba dolens (painful white leg) or phlegmasia cerulea dolens (painful blue leg)
Hypoperfusion with blanching and cyanosis
May require fluid resuscitation, immediate anticoagulation, and thrombolysis or thrombectomy

Admission Criteria

Severely ill patients
Patients with significant comorbid conditions
Patients without the means for appropriate home administration of LMWH

Discharge Criteria

Isolated DVT
No significant comorbid conditions
Resources available for home administration of LMWH
Appropriate follow-up assured

Ongoing Care

Follow-Up Recommendations

Patient Monitoring

INR levels should be evaluated frequently until stable with a target range between 2 and 3.

Diet

Patients should also be aware that certain foods high in vitamin K may diminish the anticoagulation effects of warfarin.

Patient Education

When patients are traveling, they should sit in seats that allow leg extension, take hourly walking breaks, wear loose clothing, and not cross their legs.

Prognosis

Pulmonary embolism will occur in 50% of untreated patients with DVT within days or weeks. If the DVT was caused by a thrombophilic disorder, the risk of repeat episode may be high.

Complications

Review all secondary disease or negative reactions that may occur during the course of an illness, that usually aggravate the illness, and any possible preventive measures. In addition, differentiate between acute/chronic, likelihood of complication, and common/rare.

References

1. Heit JA. Risk factors for venous thromboembolism. Clin Chest Med. 2003;24:1–12.

2. Wells PS, Anderson DR, Bormanis J, et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet. 1997;350:1795–1798.

3. Segal JB, Eng J, Tamariz LJ, et al. Review of the evidence on diagnosis of deep venous thrombosis and pulmonary embolism. Ann Fam Med. 2007;5:63–73.

4. Qaseem A, Snow V, Barry P, et al. Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Intern Med. 2007;146:454–458.

5. Segal JB, Streiff MB, Hoffman LV, et al. Management of venous thromboembolism: a systematic review for a practice guideline. Ann Intern Med. 2007;146:211–222.

Additional Reading

Hirsh J, Hoak J. Management of deep vein thrombosis and pulmonary embolism. A statement for healthcare professionals. Council on Thrombosis (in consultation with the Council on Cardiovascular Radiology), American Heart Association. Circulation. 1996;93:2212–2245.

Lensing AW, Prandoni P, Brandjes D, et al. Detection of deep-vein thrombosis by real-time B-mode ultrasonography. N Engl J Med. 1989;320:342.

Levine M, et al. A comparison of LMWH administered primarily at home with unfractionated heparin administered in the hospital for proximal DVT. N Engl J Med. 1996;334:677–681.

Meyering C, Howard T: Hypercoagulability in athletes. Curr Sports Med Rep. 2004;3:77–83.

Pearson SP, et al. A critical pathway to evaluate suspected DVT. Arch Int Med. 1995;155:1773–1778.

Wells PS, Anderson DR, Rodger M, et al. Evaluation of D-dimer in the diagnosis of suspected deep-vein thrombosis. N Engl J Med. 2003;349:1227–1235.

Codes

ICD9

451.11 Phlebitis and thrombophlebitis of femoral vein (deep) (superficial)
451.19 Phlebitis and thrombophlebitis of other
453.40 Acute venous embolism and thrombosis of unspecified deep vessels of lower extremity