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Posted: Feb. 6, 2005

Addenda: Feb. 8 & 10, 2005

Links Updated/Removed: July 13, 2011

 

What is the minimum safe platelet count prior to spinal anesthesia in the absence of thrombocytopathy?

A colleague in the Netherlands wonders if there are actual data to show the medical necessity of insisting on a platelet count of at least 100,000 per microLiter prior to spinal anesthesia in the absence of thrombocytopathy. He reports that he cannot find hard evidence for the 100,000 per microLiter limit. He asks colleagues to comment on the risk for a spinal bleed when thrombocytes are below 100,000 per microLiter, such as at 50,000 or 60,000 per microLiter. In other words, based on data, what is the lowest level of platelet count in the absence of thrombocytopathy that is reasonably safe from spinal bleed?


ADDENDA Feb. 8, 2005

The following comments have been received.

  1. Dr. Mike Murphy of the National Blood Service in the United Kingdom (attribution used with permission) reports that the topic of minimum safe platelet count prior to spinal anesthesia in the absence of thrombocytopathy has recently been discussed in the folowing references:
    • van der Veen et al in the correspondence section of the British Journal of Haematology (Br J Haematol, 2004: 127, 233-234)
    • Boulton et al (Br J Haematol, 2004, 127, 234-235)
    • Dzik WH in a chapter on 'Component therapy before bedside procedures' in Transfusion Therapy: Clinical Principles and Practice (ed Mintz PD), AABB Press, 2004
    Data on the issue of the safety of spinal anaesthesia and diagnostic lumbar puncture are limited. However, a study of over 5,000 lumbar punctures in children with acute leukaemia found no complications; 941 were performed when the platelet count was less than 50,000 per microLiter, and 170 when the platelet count was 10,000-20,000 per microLiter (Howard SC et al. JAMA, 2000:284;2222-2224). These authors concluded that it was safe to carry out lumbar puncture without platelet transfusion when the platelet count is greater than 10,000 per microLiter. Similar data were provided by van der Veen et al (2004).

    Schiffer CA et al in clinical practice guidelines for the American Society of Clinical Oncology on 'Platelet transfusions for patients with cancer' (J Clin Oncol, 2001:19;1519-1538) pointed out that lumbar puncture is often more technically difficult in adults than in children, and that it is unclear whether the exemplary safety reported by Howard et al in children could be duplicated in adults. Guidance in the British Committee for Standards in Haematology 'Guidelines for the use of Platelet Transfusions' (Br J Haematol 2003:122:10-23) was given on the basis of this information and expert opinion, and included the recommendation that the platelet count should be raised to at least 50,000 per microLiter for lumbar puncture, and epidural anesthesia.

    Given the uncertainty described above, Dr. Murphy agrees with Dr. Dzik's recommendation that prospective controlled trials, where patients with similar degrees of thrombocytopenia are randomized to receive or not receive pre-procedure platelet transfusions, are needed to definitively answer this question.

  2. Dr. Sunny Dzik of Massachusetts General Hospital (attribution used with permission) cautions that in his opinion the bleeding risk for a diagnostic LP is likely to be much less than the bleeding risk of an indwelling epidural catheter. He bases his opinion on the following data:

    "While still very infrequent, the likelihood of peridural hematoma following placement or removal of epidural catheters for spinal anesthesia appears to increase in patients receiving full-dose anticoagulation. Rao and El-Etr studied neurologic complications in the setting of low-dose systemic anticoagulation immediately following placement of either an epidural catheter (n = 3164) or a subarachnoid catheter (n= 847). Patients received spinal anesthesia with a 17-gauge needle prior to systemic low-dose anticoagulation for vascular surgery. The mean heparin dose was 10,500 units per 24 hours. Catheters were left in the spinal space during the operation for 24 hours and after transfer to the recovery care unit; they were then removed while patients were still being treated with heparin. No patients developed peridural hematomas. In a similar study by Schwander D et al, low dose heparin was not associated with spinal hematoma in over 5000 patients undergoing spinal or epidural anesthesia. However, Ruff and Dougherty reported five cases of paraplegia among 342 patients who received a diagnostic lumbar puncture and then were given systemic full-dose heparin (exact dose not stated). However, the advent of low molecular weight heparin treatment in the United States was accompanied by an increase in reported spinal hematomas among patients with epidural catheters, estimated to occur at a rate of 1 in 10,000 patients (Horlocker TT). 

    Several studies provide evidence that thrombocytopenia is not a major contraindication to diagnostic lumbar puncture. Waldman SD et al used a small (25-gauge) needle to administer morphine via a caudal block to 19 thrombocytopenic patients without neurologic complications. The patients' platelet counts were all below 50,000/µL. Rasmus et al reported that none of 14 thrombocytopenic women (platelet counts=15,000-100,000/µL) who received epidural anesthesia at the time of childbirth developed any problems. His review of the literature found no cases of spinal or epidural hematomas in women giving birth. Hew-Wing P et al reviewed the literature on the issue of epidurals and thrombocytopenia and could find no case report of a thrombocytopenic patient who developed a hematoma after epidural anesthesia. They did identify a report by Edelson RN et al of eight cases of spinal subdural hematoma among leukemia patients who had received diagnostic lumbar punctures. The authors stated that there was no supporting data to believe that epidural anesthesia should be contraindicated among patients with fewer than 100,000 platelets/µL".

ADDENDA Feb 10, 2005

  1. Dr. Pieter Henny, an anesthesiologist/intensivist at the University of Amsterdam (attribution used with permission) reports that he is aware of the literature mentioned by Dr. Murphy (posting #1) that addresses lumbar puncture and epidural anesthesia, but which does not address in detail 'spinal' anesthesia. In fact, according to Dr. Henny there may not be sufficient literature from which to draw a conclusion as to the lowest safe platelet count for spinal anesthesia. In his opinion, current guidelines are actually based on literature concerning lumbar punctures and epidural anesthesia, which are different procedures from spinal anesthesia. Dr. Henny is in agreement with the experience of Dr. Dzik (posting #2 above) that the bleeding risk of epidural anesthesia is greater than that of lumbar puncture. He cautions that any combination of compromised primary hemostasis and/or inhibition of the coagulation cascade may increase bleeding risk further. He concludes by referring colleagues to page 251 of the 2004 Dutch guidelines for blood transfusion (in Dutch only), in which a consensus was reached that a platelet count of 40,000 per microLiter, in the absence of a thrombopathy, should be sufficient for performing a lumbar puncture. Data may eventually show that the Dutch consensus opinion (which according to Dr. Henny is evidence based as far as possible), may also apply to spinal anesthesia, since lumbar puncture and epidural anesthesia are generally performed with a larger gauge needle than what is used for spinal analgesia.

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