PB 84: Prevention of Deep Vein Thrombosis and Pulmonary Embolism

Question 1

DVT is diagnosed in ~2 million Americans each year. Approximately how many of these patients develop a pulmonary embolism?

Question 2

What is the rate of VTE after gynecologic surgery in the untreated population?

Answer 2

15-40%

Question 3

How is the risk of VTE determined at time of surgery?

Answer 3

• Procedure type and duration
• Age
• Presence of other risk factors

Question 4

Risk classification for VTE in patients undergoing surgery without prophylaxis?

Answer 4

Question 5

What are 4 types of

Answer 5

1. Graded compression stockings
2. Pneumatic compression devices
3. Unfractionated heparin
4. LMWH

Question 6

Does a combined regimen of medical and mechanical prophylaxis improve efficacy of reducing VTE?

Question 7

What are the 2 most common mutations found in patients with a VTE?

Answer 7

1. Factor V Leiden
2. Prothrombin gene mutation G20210A

Question 8

Do most inherited factors of a hypercoagulable state result in clot formation?

Question 9

What is the most common inherited thrombophilia?

Answer 9

Factor V Leiden: major cause of activated protein C resistance (carried by 5% Caucasians)

Heterozygotes: 3-8 fold increased risk of VTE

Homozygotes: 50-80 fold increased risk of VTE

Question 10

How are deficiencies in Protein C, Protein S, and Antithrombin-III diagnosed?

Answer 10

Serum assays

Question 11

Common hypercoagulable states

Answer 11

Question 12

Within what time period after surgery do most thrombi develop?

Answer 12

Nearly 50% within 24 hours after surgery, 75% within 72 hours of surgery

Question 13

Pre-operative heparin use has been associated with what 2 things post-operative?

Answer 13

1. Increased postoperative bleeding
2. Hematoma formation

* DOES NOT INCREASE OPERATIVE EBL *

Question 14

What to look out for if heparin is going to be used for > 4 days?

Answer 14

Heparin-induced thrombocytopenia (6% of patients) > follow platelets

Question 15

Advantages of LMWH over unfractionated heparin?

Answer 15

• Greater bioavailability
• Once-daily dosage
• More antifactor Xa and less AT-III activity > may decrease medical bleeding and wound hematoma formation
• HIT rarely seen

Question 16

Should patients discontinue use of hormonal contraceptives or postmenopausal hormone therapy before surgery?

Answer 16

No

Although VTE is associated with estrogen and progesterone use, the overall number of events is low. No trials exist that show a reduction in postsurgical venous thromboembolism with preoperative discontinuation of hormone therapy; thus, this practice should not be routinely recommended.

Question 17

Herbs and supplements that may interfere with anticoagulant therapy

Answer 17