WHAT IS THE RISK FOR VENOUS THROMBOEMBOLISM IN PATIENTS REQUIRING NONORTHOPEDIC SURGERY?
Each year, surgeons in the United States perform more than 51 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). There have been a number of risk stratification models proposed to guide VTE prophylaxis in surgical patients; they are limited by complexity, and lack of rigorous prospective validation. However, in general, patients are considered to be at very low risk for VTE if they undergo minor surgical procedures lasting <30 minutes, have no medical comorbidities, and are immediately mobile following surgery. Their estimated baseline risk of VTE, if no prophylaxis is given, is estimated to be <0.5%. All other surgical patients are considered to be at moderate or high risk for VTE and merit some consideration for 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 56-1).
TABLE 56-1Factors that Increase Risk for Venous Thromboembolism in Surgical Patients |Favorite Table|Download (.pdf) TABLE 56-1 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 (compared with vaginal approach)
Open surgical approach (compared with laparoscopic approach)
Use of the lithotomy position intraoperatively
Extrinsic venous compression intraoperatively
Extended duration of surgery (>1 h)
Central venous catheterization
Postoperative immobility (confined to bed, needing assistance to ambulate)
Pregnancy and the puerperium
Comorbid medical illness (eg, congestive heart failure, obstructive lung disease, acute myocardial infarction, inflammatory bowel disease)
Recent ischemic stroke
Cancer (active or occult)
Prior pelvic radiation
Inherited or acquired thrombophilia
Obesity (BMI > 25 kg/m2)
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% extend and cause symptomatic DVT or PE.
WHICH PATIENTS UNDERGOING NONORTHOPEDIC SURGERY NEED VTE PROPHYLAXIS?
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 6 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 ...