Thromboprophylaxis After Vulvectomy: Fragmin 5000 IU is Appropriate
For this 73-year-old, 77kg patient undergoing vulvectomy (major pelvic cancer surgery), Fragmin (dalteparin) 5000 IU once daily subcutaneously is the correct prophylactic dose and should be continued for up to 4 weeks postoperatively. 1
Dosing Rationale
- High-dose prophylactic LMWH (dalteparin 5000 IU once daily) is specifically recommended for cancer patients undergoing major abdominal or pelvic surgery 1
- This dose has been demonstrated superior to lower doses (2500 IU) in cancer surgery patients, reducing VTE by approximately 40% without increasing bleeding complications 1
- The patient's weight of 77kg falls within the standard dosing range where fixed-dose prophylaxis is appropriate 1
Duration of Prophylaxis
Extended prophylaxis for up to 4 weeks (28-30 days) postoperatively is strongly recommended for this patient based on multiple high-risk features: 1
- Major pelvic surgery for presumed gynecologic malignancy
- Age >70 years
- Likely restricted mobility postoperatively
The evidence shows extended prophylaxis reduces VTE risk by 60% compared to standard 7-10 day prophylaxis in this population 1
Renal Function Considerations
If this patient has normal or mildly impaired renal function (CrCl ≥30 mL/min), no dose adjustment is needed: 2, 3, 4, 5
- Multiple studies demonstrate dalteparin 5000 IU daily does not bioaccumulate even in patients with severe renal insufficiency (CrCl <30 mL/min) 3, 4, 5
- In the CLOT study subanalysis, dalteparin at standard prophylactic doses was safe and effective in cancer patients with CrCl <60 mL/min 2
- Trough anti-Xa levels remain undetectable or very low (<0.10 IU/mL) even after weeks of prophylactic dosing in renal impairment 5
However, if severe renal impairment exists (CrCl <30 mL/min), consider: 6, 2
- Anti-Xa monitoring (though not routinely required) 2
- Unfractionated heparin 5000 units every 8-12 hours as an alternative if concerns about accumulation exist 1, 6
Monitoring and Safety
Routine monitoring is not required, but check: 1
- Hemoglobin, hematocrit, and platelet count every 2-3 days up to day 14, then every 2 weeks 1
- Assess for signs of bleeding or thrombosis clinically
- Major bleeding risk with prophylactic dalteparin is approximately 3-4% in surgical cancer patients 1
Common Pitfalls to Avoid
- Do not use lower doses (2500 IU) - this is inadequate for cancer surgery patients and increases VTE risk 1
- Do not stop prophylaxis at hospital discharge - the highest VTE risk period extends 3-4 weeks postoperatively 1
- Do not withhold LMWH solely due to age or mild-moderate renal impairment - the evidence supports safety in these populations 2, 3, 4, 5
- Do not use twice-daily dosing for prophylaxis - once-daily dalteparin 5000 IU is the evidence-based regimen 1
Contraindications to Continue
Stop dalteparin if: 1
- Active major bleeding (>2 units transfused in 24 hours)
- Platelet count <50,000/mcL
- Development of heparin-induced thrombocytopenia (switch to fondaparinux or direct thrombin inhibitor)
- Recent CNS bleeding or high-risk intracranial lesion