Platelets: too much, too little, don’t work. The approach to platelet emergencies is perhaps a little bit more complicated than that, so we attempt to breakdown a simplified approach to platelets in the Emergency Department (ED). Patients with various disease processes often present to the emergency department with critically low platelet counts.
When should we consider transfusing these patients prophylactically to prevent bleeding? 
Some of these patients may require a procedure (such as lumbar puncture, central line or paracentesis) in the ED. 
When is it safe to do these procedures? When should we consider transfusing during/prior to these procedures to prevent severe bleeding?
The following should provide a simple guide to some of these platelet-related dilemmas in the ED.

Prophylactic platelet transfusions:

1. Thrombocytopenia associated with chemotherapy:

  • Most studies of spontaneous bleeding derived from hospitalized patients with hematologic malignancies receiving high dose chemotherapy.1
    • These patients are at high risk of spontaneous bleeding due to vascular insults from chemotherapy
  • Major bleeding (WHO grade 2 or higher):
    • Increases at platelets < 20
    • Increases dramatically at platelets < 10
    • Increases with fever/infection
  • Most guidelines and institutions recommend giving 1 adult dose of platelets for Plt < 10 or Plt < 20 with fever in hospitalized patients.3-5
  • In the ED, consider transfusing platelets for any chemotherapy associated thrombocytopenic patient with platelets < 20.
    • Factors to consider:
      • Next follow up.
      • Distance and practicality of followup appointments.
      • Rate of platelet count decrease (if known).
      • Available hospital resources: can they be seen next day in medical day unit to receive transfusion?
      • Do they need to be admitted due to systemic illness, infection, etc.

2. Thrombocytopenia associated with ideopathic thrombocytopenic purpura(ITP):

  • Platelet transfusions are usually not indicated unless there is severe bleeding.
    • Very low risk of spontaneous bleeding (< 1% / yr for age< 60).6
    • Spontaneous bleeding increases at around Plt < 20.7 
  • Management (usually in conjunction with a hematologist):8,9
    • Severe bleeding present:
      • IVIG 1g/kg
      • Methylprednisolone 1g IV
      • Platelet transfusion
      • Tranexamic acid 1g IV over 10 min then 1g IV over 8 hours
      • Hematology consult
    • Severe bleeding absent:
      • Platelets < 30
        • IVIG, steroids, immunosuppressive therapy or thrombopoietin receptor agonists, splenectomy
      • Platelets > 30
        • Observe, consider treatments above if minor bleeding uncontrolled.
        • Timely follow up.

3. Thrombocytopenia associated with liver disease:

Patients with liver disease have many reasons to be hypo/hyper-coagulable, therefore, the balance of bleeding vs. clotting in these patients is unpredictable, and not reflective of coagulation studies.
Fortunately, in these patients Plt < 30 are uncommon (~5%) and Plt <20 are rare (<1%).11
Therefore, in the EDonly transfuse platelets for severe bleeding.

4. Other scenarios:

  • Are platelet transfusions contraindicated in patients with TTP or HIT?
    • No absolute contraindications to giving platelets.12-14
    • One large retrospective database review suggests NNH = 75 (TTP) and NNH = 26 (HIT) for arterial thrombosis and no increased risk of VTE when platelets are given.15
    • Therefore, must balance risk of severe bleeding vs thrombosis on an individual level.
  • Should strongly consider transfusing platelets in the following situations3:
    • DIC or life threatening bleeding
      • If patients platelets < 50
    • ICH
      • If patients platelets < 100
    • Life threatening bleeding related to anti-platelet medications
      • Transfuse 2-3 adult doses of paltelets

ED Procedures and Thrombocytopenia

1. Lumbar puncture

  • Thrombocytopenia

    • Older case reports of spinal hematomas with Plt < 20.17,18
    • Several studies demonstrate safety of LP at Plt < 20.19,20
    • Safe threshold somewhere likely between Plt 20-50
    • Most guidelines recommend platelet transfusion for Plt < 50 prior to LP as a safe margin (given potentially devastating consequence of spinal hematoma).3,4,5,21

Bottom line: In the ED, strongly consider using platelets < 50 as threshold for transfusion prior to lumbar puncture. 

  • Antiplatelets

    • ASA
      • Several retrospective studies on patients receiving epidurals while on ASA.
        • No reported spinal hematomas.22-24
        • European Society of Anaesthesiology (ESA) and American Society of Regional Anesthesia (ASRA) guidelines suggest it is safe to proceed with LP.25,26
    • Clopidogrel
      • Surgical studies reliably demonstrate increased bleeding compared to ASA.
      • 2 case reports of spinal hematomas in patients receiving epidural catheters while on Clopidogrel (but also confounded by receiving dose of Enoxaparin, Dalteparin).27,28
      • ESA/ASRA guidelines suggest is unsafe to proceed with LP.22,23
      • However, these recommendations are based on case reports, in which patients also received heparin – so these recommendations should be taken with a grain of salt. There is a potential risk, so case based considerations and shared decision making should be utilized. 

Bottom line: Lumbar puncture is safe in patients on ASA, but should require some careful consideration before being performed on patients on Clopidogrel.

2. Paracentesis

  • Rate of severe bleeding exceedingly low despite INR ranges 0.9-8.7 and platelets as low as 19 in 2 large studies.29,30
    • Severe bleeding usually caused by vessel puncture, not coagulopathy.
    • As previously mentioned, the occurrence of platelets < 20 is rare in patients with liver disease.11

Bottom linePlatelet transfusions are rarely/never required prior to paracentesis.

3. Central Venous Catheters (CVCs)

  • One study of 604 CVCs had a 32% bleed rate.31
    • 96% grade 1, 4% grade 2 (prolonged compression).
    • Demonstrated increased OR of bleeding only for platelets < 20. 
  • Another study reports 57 plasma exchange catheters for presumed TTP.32
    • 29 for platelets < 30, 10 for platelets < 10, and 28 patients for platelets > 30. 
    • NO difference in minor bleeding (~30% for each group).
    • No major bleeding requiring intervention.
  • Most guidelines suggest transfusion for Plt < 50.3,5,21
  • AABB 2015 guidelines recommend transfusion for plt < 20.4

Bottom lineIn the ED, can probably use platelets < 20 as threshold for pre-procedure platelet transfusion for CVC insertion:

  • Use ultrasound guidance
  • Utilize a potentially compressible site (IJ, femoral). 
  • Experienced practitioner. 

Take Home Points

Dr. Michael Ho is a 4th year Emergency Medicine resident at the University of Ottawa, with a special interest in medical education and resuscitation.
Edited by Dr. Shahbaz Syed, 4th year Emergency Medicine resident, University of Ottawa


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