Each year, surgeons in the United States perform more than 46 million inpatient surgeries, the majority of which are nonorthopedic surgeries. Patients undergoing nonorthopedic surgeries are a heterogeneous group in terms of surgery type, comorbidities, and associated risk for venous thromboembolism (VTE), which comprises deep vein thrombosis (DVT) and pulmonary embolism (PE). Patients at low risk for VTE typically undergo surgical procedures lasting less than 30 minutes, are immediately mobile following surgery, or are already receiving therapeutic-dose anticoagulant therapy. All other surgical patients are considered to be at moderate or higher risk for VTE and merit some form of prophylaxis. VTE in the patient undergoing nonorthopedic surgery can cause significant morbidity and mortality and is a common cause of readmission to the hospital.
Many factors contribute to VTE after nonorthopedic surgery (Table 58-1).
Table 58-1 Factors that Increase Risk for Venous Thromboembolism in Surgical Patients ||Download (.pdf)
Table 58-1 Factors that Increase Risk for Venous Thromboembolism in Surgical Patients
Antecedent trauma (as reason for surgery)
General anesthesia (compared with regional/local anesthesia)
Abdominal surgical approach (ie, compared with vaginal approach)
Open surgical approach (ie, compared with laparoscopic approach)
Use of the lithotomy position intraoperatively
Extrinsic venous compression intraoperatively
Extended duration of surgery (ie, >1 hour)
Central venous catheterization
Immobility (confined to bed, needing assistance to ambulate)
Pregnancy and the puerperium
Acute medical illness (eg, congestive heart failure, obstructive lung disease)
Acute ischemic stroke
Acute neurologic disease
Inflammatory bowel disease
Cancer (active or occult)
Prior pelvic radiation
Inherited or acquired thrombophilia
Drugs (eg, chemotherapy, hormonal therapy, erythropoeisis stimulating agents)
Trauma and surgery both contribute to venous injury and activation of the coagulation system. Postoperatively, patients may have persistently reduced mobility, which causes stasis of blood flow in the deep venous system. Patients undergoing certain types of surgery may also have independent risk factors for VTE, such as obesity in the bariatric surgical patient.
As in the orthopedic surgery setting, most episodes of postoperative DVT in nonorthopedic surgery are clinically silent. These unnoticed clots usually resolve spontaneously without administration of antithrombotic therapy. However, 25% to 50% grow and cause symptomatic DVT or PE.
Does This Patient Undergoing General Surgery Need VTE Prophylaxis?
A 32-year-old mother of two comes to the emergency room with abdominal pain and nausea. An ultrasound confirms acute appendicitis, and the general surgeon at your center feels this patient should have an appendectomy within the next six hours. He feels she is at low operative risk, since she has no past medical history and is taking no medications, apart from an oral contraceptive pill. The general surgery resident phones you to ask ...