When to Hold Enoxaparin for DVT Prophylaxis Based on Platelet Count

Enoxaparin for DVT prophylaxis should be held when platelet counts fall below 50,000/mcL due to increased bleeding risk. 1

Platelet Count Thresholds for Anticoagulation

Thrombocytopenia with platelets <50,000/mcL is considered a relative contraindication to anticoagulation, including prophylactic enoxaparin 1
This threshold is based on the significantly increased risk of bleeding complications when platelets fall below this level 1
For patients receiving prophylactic enoxaparin, regular monitoring of platelet counts is recommended, especially during the first 14 days of therapy 1

Following initiation of enoxaparin: hemoglobin, hematocrit, and platelet count should be checked every 2-3 days for the first 14 days 1
After the initial 14 days, monitoring should continue every 2 weeks or as clinically indicated 1
For patients at higher risk of heparin-induced thrombocytopenia (HIT), more frequent monitoring may be warranted 1

While the risk of HIT is lower with LMWH compared to unfractionated heparin, it remains a concern 1
HIT typically presents with a ≥50% drop in platelet count within 5-10 days after starting heparin (earlier with previous exposure) 1
For patients with a risk of HIT of ≥1%, platelet count monitoring every 2-3 days from day 4 to day 14 is recommended 1

Cancer patients are at particularly high risk for both VTE and bleeding complications 1
The risk of thrombocytopenia may be higher in cancer patients due to chemotherapy, bone marrow involvement, or other factors 1
Table 3 in the ASCO guidelines identifies platelet count >350,000/μL as a risk factor for cancer-associated thrombosis, while low platelet counts increase bleeding risk 1

Fondaparinux may be considered as an alternative in patients with HIT, as it has an insignificantly low risk of causing HIT 1
Direct oral anticoagulants (DOACs) like rivaroxaban or apixaban may be options for patients who cannot receive LMWH, though these are typically used for treatment rather than prophylaxis 1
For patients with severe thrombocytopenia requiring VTE prophylaxis, mechanical methods such as intermittent pneumatic compression devices should be considered 1

Enoxaparin prophylaxis can be resumed when platelet counts recover to >50,000/mcL 1
The decision to resume should consider the patient's overall bleeding risk and the indication for prophylaxis 1
Close monitoring of platelet counts should continue after resumption of therapy 1

Failing to monitor platelet counts regularly in patients receiving enoxaparin 1
Not recognizing that thrombocytosis can also be a rare adverse effect of enoxaparin therapy 2, 3
Overlooking the need for dose adjustments in patients with renal impairment, which can lead to accumulation and increased bleeding risk 1
Continuing prophylactic anticoagulation in patients with active major bleeding (>2 units transfused in 24 hours), which is an absolute contraindication 1