Safety of Lumbar Punctures in Adult Oncology Patients with Thrombocytopenia
Authors: Ning Shuoyan , Kerbel Brent , Callum Jeannie , Lin Yulia 
Published: October 2019

Abstract
Introduction: Lumbar puncture (LP) is a frequently performed diagnostic and therapeutic intervention in adult oncology patients. While thrombocytopenia is common in this patient population, the minimum "safe" platelet count required for LPs is unknown. Recent guidelines from the AABB (American Association of Blood Banks) recommend a pre-procedure platelet count of 50 x 109/L. However this recommendation is largely based on expert opinion, and there remains a paucity of studies in the adult oncology literature to address this important question.
Methods: We retrospectively reviewed all oncology patients ≥18 years who underwent 1 or more LPs over a 2 year period at a single tertiary care institution to determine 1) the range of platelet counts at which LPs are performed; 2) the rate of traumatic taps; and 3) the rate of hemorrhagic complications. Laboratory, clinical, and transfusion information were extracted through the Laboratory Information System, chart review, and blood bank database, respectively. Thrombocytopenia was defined as a platelet count of < 150 x 109/L. Pre-LP platelet counts were those collected ≤24 hours from, and closest to the time of the LP. The following bleeding risk factors were documented: end stage renal disease; platelet dysfunction; von Willebrand disease; hemophilia. Anticoagulation, anti-platelet, and non-steroidal inflammatory use was also recorded, with accuracy limited by the study's retrospective nature. All patients with coagulopathy were excluded (INR ≥ 1.5, aPTT ≥ 40, fibrinogen ≤ 1.0). Traumatic tap was defined as 500 or more red blood cells per high-power field in the cerebrospinal fluid. A follow up of 1 week after LP was used to capture any hemorrhagic complications.
Results: From January 2013 to December 2014, 135 oncology patients underwent 369 LPs; 64 (47.4%) patients were female, and the mean age was 59 years (range 20-87). 119 (88.1%) patients had a primary hematological diagnosis. 113 (30.6%) LPs were performed in thrombocytopenic patients. 28 (7.6%) procedures had a pre-procedure platelet count of ≤ 50 x 109/L, with 18 receiving a single platelet transfusion on the day of the LP. Of these 18 transfusions, only 1 had a post-transfusion platelet count available prior to LP with no improvement in platelet count (33 x 109/L). 15 transfusions had post-LP platelet counts within 24 hours of the transfusion (8 below 50 x 109/L with lowest 14 x 109/L), 1 had post-LP platelet count within 24-48 hours (54 x 109/L) and 1 did not have a post-transfusion platelet count. Traumatic taps occurred in 17 (15.0%) LPs in patient with thrombocytopenia, compared to 26 (11.0%) LPs in patients with a normal platelet count (fisher's exact test P=0.39). There was 1 traumatic tap in a patient with a pre-LP platelet count of ≤ 50 x 109/L; however, this patient received a pre-LP platelet transfusion for a platelet count of 42 x 109/L and had a post-LP platelet count of 66 x 109/L. Presence of bleeding risk factors did not increase the risk of a traumatic tap (present in 48.8% of traumatic taps vs. 88.3% of non-traumatic taps). There were no hemorrhagic complications.
Conclusion: Among this cohort of adult oncology patients undergoing diagnostic and therapeutic LPs, there were no hemorrhagic complications. There was no significant increase in traumatic taps in patients with thrombocytopenia or bleeding risk factors. While platelet transfusions were frequently administered for patients with a platelet count of ≤ 50 x 109/L, post-transfusion platelet counts were infrequently assessed prior to the procedure. Our findings question whether a platelet transfusion threshold of 50 x 109/L is necessary for lumbar puncture.Table 1.Platelet Count Pre-LP(x109/L)Number of LPsNumber of Traumatic TapsNumber of Hemorrhagic Complications0-90N/AN/A10-2030021-5070051-1003380101-1495270> 150242270Unknown1400< 50 x 109/L and received platelet transfusion on day of LP181*0Total369430*There was one traumatic tap in a patient with a platelet count of 42 x 109/L who received a platelet transfusion pre-LP. The post transfusion platelet count was 66 x 109/L.

Disclosures
No relevant conflicts of interest to declare.