Traditionally, it has been promulgated by anesthesiologists that you need a platelet count of 100,000 to safely perform neuraxial regional anesthesia (spinal and epidural anesthesia). This practice pattern has continued even though Children’s Hospitals routinely perform intrathecal injections for prophylactic chemotherapy with platelet counts as low as 20K in patients with lymphoma/leukemia. In a study of 5223 lumbar punctures in children, 941 children had a PLT ~50K and no epidural hematomas were reported and 199 children had a PLT ~20K and no epidural hematomas were reported. The calculated risk of a spinal hematoma for a PLT 20K was 0 – 1.75% and the calculated risk of a spinal hematoma for a PLT 50K was 0 – 0.37% .1 In addition, the argument that platelets do not work as well during pregnancy vs in cancer patients does not fly either. Analysis of platelet function using a PFA-100 analyzer (Dade Behring, Liederbach, Germany) showed that a platelet count of 60,000/mm3 in a parturient with pregnancy-induced thrombocytopenia functioned similarly to platelet counts that were greater than 150,000/mm3.2
In one single-center retrospective study of 20,244 obstetric patients, peripartum thrombocytopenia (platelet count <100,000/mm3) occurred in 368 patients. Of these patients, 69% (256) received neuraxial anesthesia. No neuraxial hematoma occurred in any of these patients.3 Based on this and similar studies, many anesthesiologists feel comfortable performing neuraxial regional anesthesia with a PLT count 75-80K. Why not lower than this? Completely unclear because there is no data to support lack of safety at lower PLT levels.
So what is the data of the safety of lumbar puncture in adults and children? Eight single center retrospective studies of lumbar puncture in children with thrombocytopenia had:
39 LP with PLT <10K
204 LP with PLT 11-20K
817 LP with PLT 20-50K
No serious bleeding complications in these studies
Four studies analyzed LP in adults with thrombocytopenia and total of 102 lPs with PLT 20-50K and no serious bleeding complications were noted.4,5
Finally, organizations in different countries have different PLT cut-offs for when they recommend PLT transfusion before a lumbar puncture. The American Association of blood banks recommends a PLT cut-off of 50K whereas the American National Red Cross and the Dutch blood transfusion guideliness each recommend a cut-off of 40K below which they would recommend a PLT transfusion in adults. In children, the British Committee for the standards in hematology recommend a PLT cut-off of 20-40K and the C17 guidelines recommend a PLT cut-off of 20K below which they would recommend a PLT transfusion before an LP.4,5
Based on these data, I and many other procedural experts and organizations recommend a safe platelet threshold of 40K as a safe level at which or above one may perform a lumbar puncture without preprocedural administration of platelets. This assumes that a patient is not taking an anticoagulant, a thienopyridine antiplatelet agent and has no qualitative platelet dysfunction as can occur with uremia.