IN THIS ARTICLE
Pulmonary embolism is a master of disguises. It can appear with classic symptoms such as pleuritic chest pain, hemoptysis, and tachycardia—or it can arrive more insidiously, apparent only as a slight elevation in the respiratory rate.
This matters because 40% of all deaths following gynecologic surgery are directly attributable to pulmonary emboli,1 and pulmonary emboli are the most frequent cause of postoperative death in women with uterine or cervical carcinoma.2
Deep venous thrombosis (DVT) is almost as evasive. We know the signs and symptoms of DVT of the lower extremities—pain, edema, erythema, and a prominent vascular pattern of the superficial veins—but 50% to 80% of patients with these symptoms do not have DVT, and 80% of patients with symptomatic pulmonary embolism have no antecedent signs of thrombosis in the lower extremities.2 Morbidity and expense rise dramatically with DVT, especially when postphlebitic syndrome occurs.
How can we minimize these risks?
A good outcome is most likely when we:
- recognize risk factors,
- provide appropriate perioperative prophylaxis, and
- diagnose and treat venous thromboembolism (VTE) quickly.
This article looks in detail at each of these strategies.
3 factors set the stage for thrombogenesis
- Hypercoagulable state
- Venous stasis
- Vessel endothelial injury
These factors, known as Virchow’s triad, are especially likely at the time of major surgery, or when the patient is advanced in age or has a history of DVT, cancer, lower extremity edema, or venous stasis.
Intraoperative risk factors for postoperative DVT include increased anesthesia time, greater blood loss, and need for transfusion.
Some preventive methods come close to ideal
Being aware of risk factors is vital to provide the appropriate level of prophylaxis (TABLES 1 AND 2).3,4 The first step is identifying high-risk patients and tailoring the regimen to meet their individual needs. The perfect prophylactic method is not yet devised, but would be effective, free of significant side effects, well accepted by the patient and nursing staff, widely applicable to most patient groups, and inexpensive. A number of methods come close.
TABLE 1
Risk factors for thromboembolism
| Major gynecologic surgery |
| Age >40 years |
| Malignancy |
| Previous venous thrombosis (DVT or pulmonary embolism) |
| Obesity |
| Immobility |
| Pregnancy and the postpartum period |
| Oral contraceptives, hormone therapy, or tamoxifen |
| Varicose veins |
| Inherited or acquired thrombophilia (eg, Factor V Leiden) |
| Prolonged surgical procedure |
| Radical vulvectomy, inguinal-femoral lymphadenectomy, or pelvic exenteration |
TABLE 2
Match the preventive strategy to the surgery
| SURGERY | STRATEGY | DURATION OF PROPHYLAXIS* |
|---|---|---|
| Procedures <30 min for benign disease | Prophylaxis not needed | — |
| Laparoscopic gynecologic procedures in women with additional risk factors | Unfractionated heparin, 5,000 bid or | Until hospital discharge |
| LMWH, ≤3,400 U/day or | ||
| External pneumatic compression or | ||
| Graduated compression stockings | ||
| Major surgery for benign disease without additional risk factors | Unfractionated heparin, 5,000 U bid or | Until hospital discharge |
| LMWH, <3,400 U/day or | ||
| External pneumatic compression | ||
| Extensive major surgery in women with cancer or additional risk factors | Unfractionated heparin, 5,000 U tid or | Until hospital discharge |
| LMWH, >3,400 U/day or | ||
| External pneumatic compression | ||
| *For women at particularly high risk (eg, cancer surgery, age >60 years, prior VTE), continue prophylaxis for 2–4 weeks after hospital discharge. | ||
| Modified from Geerts WH, et al20 | ||
Low-dose unfractionated heparin
The most extensively studied prophylactic method is the use of small, subcutaneous doses of heparin. More than 25 controlled trials have shown that, when heparin is given subcutaneously 2 hours before surgery and every 8 to 12 hours afterward, the incidence of DVT diminishes substantially.
The value of low-dose heparin in preventing pulmonary emboli was established by a randomized, controlled, multicenter, international trial, in which fatal postoperative pulmonary emboli declined significantly in general surgery patients given the drug every 8 hours after surgery.5 In gynecologic surgical patients, postoperative DVT also declined significantly.
Increase in minor bleeding complications. Although low-dose heparin is thought to have no measurable effect on coagulation, most large series have noted an increase in minor bleeding complications such as wound hematoma. Up to 10% to 15% of otherwise healthy patients develop transiently prolonged activated partial thromboplastin time (APTT) after 5,000 U of heparin are given subcutaneously.6
Although relatively rare, thrombocytopenia is associated with the use of low-dose heparin. It has been found in 6% of women after gynecologic surgery.6 Therefore, it is reasonable to measure platelets in any patient taking low-dose heparin longer than 4 days to screen for heparin-induced thrombocytopenia.