Joshua D. Roth, MD
Michael O. Koch, MD, FACS
BASICS
DESCRIPTION
• Deep vein thrombosis (DVT): Aggregation of platelets and fibrin within a deep vein of the leg or pelvis that may lead to venous obstruction.
• Pulmonary embolism (PE): Blockage of the pulmonary artery or one of its branches by a thrombus that has traveled from elsewhere in the body through the bloodstream. Can be an acute life-threatening illness.
• Venous thromboembolism (VTE or DVT/PE) is the disease process by which a DVT can embolize and become a life-threatening PE.
EPIDEMIOLOGY
Incidence
• DVT
– 160/100,000/yr (1)
– Increases with age: 1/100 if age ≥80
• PE (1)
– 70/100,000/yr, with a 1-wk survival rate of 71%; 25% present with sudden death
– PE is believed to be the most common cause of postoperative death in the urologic population
• VTE risk in urologic populations (2)
– Radical cystectomy: 3.7%
– Percutaneous nephrostomy in patients with/without malignancy: 3.6%/0.8%
– Nephrectomy with/without malignancy: 2.0%/0.4%
– Radical prostatectomy: 1.5%
– Transurethral resection of bladder tumors/prostate: <0.5%
– Incontinence repair: 0.3%
Prevalence
Prevalence of genetic mutations causing inherited thrombophilia: <1–5%, which cause a 3–10× increase risk of VTE in heterozygous state (3)
RISK FACTORS
• Patient-specific risk factors (1)
– Surgery
– Trauma (major or lower extremity)
– Immobility, paresis
– Malignancy
– Cancer therapy (hormonal, chemotherapy, or radiotherapy)
– Previous VTE
– Increasing age (≥60)
– Pregnancy and the postpartum period
– Estrogen-containing oral contraception
– Selective estrogen receptor modulators
– Acute medical illness
– Heart or respiratory failure
– Inflammatory bowel disease
– Nephrotic syndrome
– Myeloproliferative disorders
– Paroxysmal nocturnal hemoglobinuria
– Obesity
– Smoking
– Varicose veins
– Central venous catheterization
– Inherited or acquired thrombophilia
Genetics
• Inherited risk factors for DVT/PE (3)
– Family history
– Factor V Leiden mutation
– Prothrombin G20210A
– Protein C deficiency
– Protein S deficiency
– Antithrombin deficiency
– Sickle cell trait
PATHOPHYSIOLOGY
• Most PEs arise from DVTs
• DVTs arise from initiating factors of Virchow’s triad:
– Hypercoagulability: Regional activation of coagulation cascade leading to obstruction, edema, pain
– Stasis: Stagnant hypoxemia causes endothelial injury
– Injury: Platelet accumulation and fibrin deposition
• Need to differentiate from superficial thrombophlebitis/thrombosis that does not usually lead to DVT/PE
ASSOCIATED CONDITIONS
Paradoxical embolism: Systemic embolisms of venous origin that occur in patients with atrial or ventricular septal defects, which allow the embolus to pass into the arterial circulation
GENERAL PREVENTION
• DVT prophylaxis (ppx)
– Mechanical (nonpharmacologic) therapies
Early postoperative ambulation
Graduated compression stockings (GCSs)
Intermittent pneumatic compression (IPC)
– Pharmacologic therapies
Subcutaneous low-dose unfractionated heparin (LDUH)
Subcutaneous low–molecular-weight heparin (LMWH)
• Recommendations (4)
– Very low–risk surgery (VTE risk <0.5%)
No specific pharmacologic (B) or mechanical (C) ppx
– Low-risk surgery (VTE risk ∼1.5%)
Mechanical ppx, preferably with IPC (C)
– Moderate-risk surgery (VTE risk ∼3.0%) who are not at high risk for bleeding complications
LMHW/LDUH (B), or mechanical ppx, preferably with IPC (C)
– Moderate-risk surgery (VTE risk ∼3.0%) who are at high risk for bleeding complications
Mechanical ppx, preferably with IPC (C)
– High-risk surgery who are not at high risk for bleeding complications
LMHW/LDUH (B) and mechanical ppx, with IPC or GCS (C)
– High-risk patient undergoing cancer surgery who are not at high risk for bleeding complications
4 wk of LMWH (B)
– High-risk patient who are at high risk for bleeding complications
Mechanical ppx, preferably with IPC until the risk of bleeding diminishes
– High-risk patients with contraindications to LMWH/LDUH who are not at high risk for bleeding complications
Low-dose aspirin (C), fondaparinux (C), or mechanical ppx, preferably with IPC (C)
– Inferior vena cava (IVC) filters should not be used for primary VTE prevention
– No need for periodic ultrasound surveillance
DIAGNOSIS
HISTORY
• Recent high-risk surgery, or other risk factors for VTE
– DVT
History of prolonged immobilization, postoperative stasis, especially in patient with risk factors
Complaint of calf pain, swelling, or discoloration
– PE
High clinical suspicion with above history
Acute onset of dyspnea, tachycardia, arrhythmia, hypotension
PHYSICAL EXAM
• DVT: Determined by level of obstruction
– Inspection: Unilateral edema, discoloration below level of occlusion, dilated superficial veins
– Palpation: Tender cord or knot, Homans’ sign (limitation of passive dorsiflexion of foot, 55% unreliable)
• PE
– Inspection: Cyanotic, dyspneic, prominent jugular veins, hemoptysis, tachypnea
– Palpation: Tachycardia, arrhythmia
– Auscultation: Pleural rub, rales, S3–S4 heart sounds
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• DVT
– D-dimers: Sensitivity approaches 95% for ELISA method
• PE
– ABG: Increased P(A-a)O2 gradient
– PaO2 <80 mm Hg
Imaging
• DVT
– Central venography (gold standard): Invasive, expensive, not always available, contrast risks
– Doppler ultrasound (US)/sonography: 90% accurate above knee, versatile, noninvasive, painless
– Venous duplex ultrasound
Grayscale US to visualize the structure of the veins and color Doppler US to visualize the flow of blood through the vein; more accurate than Doppler and plethysmography
• PE
– Chest x-ray (CXR)
Generally unremarkable, but can sometimes see a small, unilateral effusion
Westermark sign: Asymmetric vascular markings with segmental or lobar ischemia
– Ventilation/perfusion scan (V/Q scan)
A perfusion defect in ≥1 pulmonary segment or all unmatched with ventilation defects support a high probability of PE
Negative result is very predictive
– Computed tomography (CT)
Most common test used to diagnose PE
Diagnostic Procedures/Surgery
• Pulmonary Angiography
– Injection of contrast into the pulmonary circulation, fluoroscopy of the lungs
– Gold standard for diagnosing PE; rarely done
Pathologic Findings
Thrombi are a woven congealed mass of fibrin and platelets
DIFFERENTIAL DIAGNOSIS
• DVT: Cellulitis, thrombophlebitis, muscle sprain/strain, claudication, lymphedema
• PE: Pneumonitis/pneumonia, pneumothorax, CHF, esophageal perforation, myocardial infarction
TREATMENT
ALERT
DVT and PE are potentially life-threatening and acute decline in status can occur. This condition must be treated/diagnosed quickly and level of suspicion must always be high in postoperative patients.
GENERAL MEASURES
• DVT: Extremity elevation, early ambulation, pain relief
• PE: Oxygen therapy, fluid resuscitation, maintain cardiac output with pressors if needed
• Overall management of anticoagulation and antiplatelet therapy can be found in Section VII: Reference Tables: Anticoagulation and Antiplatelet Therapy in Urologic Practice
MEDICATION
First Line
• DVT proximal to knee anticoagulation with (4):
– LMWH
– Fondaparinux
– Above favored over IV unfractionated heparin (UH) drip (B)
– Early initiation of oral warfarin, with continued parenteral anticoagulation until INR is reached for >24 hr.
• DVT Distal to knee
– Without severe symptoms/risk factors: Serial noninvasive imaging for 2 wk over anticoagulation (C). If thrombus extends, recommend therapeutic anticoagulation (B/C).
– With severe symptoms/risk factors: Anticoagulation (as above) over imaging (C).
• PE (4)
– Systemic anticoagulation as for DVT (B/C)
– PEs with hypotension: Systemic thrombolysis with streptokinase is recommended (C).
Second Line
• DVT/PE
– In patients with heparin-induced thrombocytopenia (HIT), LMW heparin (argatroban, lepirudin, and danaparoid) can be used
SURGERY/OTHER PROCEDURES
• DVT
– Venous thrombectomy: Rarely needed
– IVC filter:
Used as prophylaxis in high-risk or multitrauma patients
Recommended for acute DVT with contradic-tion to anticoagulation (4)[B]
• PE
– Pulmonary embolectomy: Considered rarely for patient who remains in shock despite medical therapy
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
• Will need 3 mo of anticoagulation therapy for postsurgical DVT/PE (4)[B]
• Protamine can reverse unfractionated heparin if needed. Protamine is not as effective with LMWH but should be used if excessive bleeding is encountered
Complementary & Alternative Therapies
N/A
ONGOING CARE
PROGNOSIS
• 10–30% of all patients with VTE suffer mortality within 30 days (3)
• Following anticoagulation therapy, 1/3 of all VTE patients will experience a recurrence within 10 yr (3)
– Highest risk of recurrence is in the 1st year (3)
• 1/3–1/2 of those with LE DVTs develop postthrombotic syndrome (3)
COMPLICATIONS
• DVT: Pulmonary embolus; postthrombotic syndrome: Destruction of valves leads to chronic pain, swelling, skin necrosis, ulceration
• PE: Death, pulmonary infarction, pain, arrhythmia, shortness of breath
• VTE: Requires anticoagulation with its associated risk factors (increased bleeding risk), increased healthcare costs, prolonged hospitalization, rehospitalizations
• Heparin-induced thrombocytopenia with unfractionated heparin
FOLLOW-UP
Patient Monitoring
• Patients on heparin: Follow aPTT
• If necessary LMWH therapy can be followed by antifactor Xa assays
• Patients on warfarin need close monitoring of their INR for a goal between 2.0 and 3.0 (3)[B]
Patient Resources
• The Coalition to Prevent Deep-Vein Thrombosis http://www.preventdvt.org
• The National Blood Clot Alliance http://www.stoptheclot.org
REFERENCES
1. Rice KR, Brassell SA, McLeod DG. Venous Thromboembolism in Urologic Surgery: Prophylaxis, Diagnosis, and Treatment. Rev Urol. 2010;12(2/3):e111–e124.
2. White RH, Zhou H, Romano PS. Incidence of symptomatic venous thromboembolism after different elective or urgent surgical procedures. Thromb Haemost. 2003;90:446.
3. Beckman MG, Hooper WC, Critchley SE, et al. Venous thromboembolism: A public health concern. Am J Prev Med. 2010;38(4S):S495–S501.
4. Guyatt GH, Akl EA, Crowther M, et al. Executive summary: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(suppl 2):7S–47S.
ADDITIONAL READING
Best Practice Statement for the Prevention of Deep Vein Thrombosis in Patients Undergoing Urologic Surgery, AUA 2008. Accessed March 2013 at http://www.auanet.org/content/media/dvt.pdf
See Also (Topic, Algorithm, Media)
• Reference Tables: Anticoagulation and Antiplatelet Therapy in Urologic Practice
• Deep Venous Thrombosis and Pulmonary Embolus, Urologic Considerations Image 
• Deep Venous Thrombosis, Prophylaxis, AUA Guidelines
CODES
ICD9
• 415.11 Iatrogenic pulmonary embolism and infarction
• 453.40 Acute venous embolism and thrombosis of unspecified deep vessels of lower extremity
• 997.2 Peripheral vascular complications, not elsewhere classified
ICD10
• I26.99 Other pulmonary embolism without acute cor pulmonale
• I82.409 Acute embolism and thrombosis of unspecified deep veins of unspecified lower extremity
• T81.72XA Complication of vein following a procedure, NEC, init
CLINICAL/SURGICAL PEARLS
• Prophylaxis can help prevent DVT/PE.
• PE usually develops from a venous thrombus involving the proximal lower extremity.
• DVT/PE are potentially life threatening—have a high index of suspicion.
• Early diagnosis and treatment are key.