Class 1 evidence to inform decisions about the safety of lumbar punctures in patients with a coagulopathy are lacking. The only guidance we have regarding the safety of lumbar punctures is based on clinical guidance from organizations such as the American Society of Regional Anesthesia and Pain Medicine (ASRA) and the Society of Interventional Radiology (SIR). These societies recommend that lumbar punctures or neuraxial regional anesthesia (spinal or epidural anesthesia) can be performed if: INR≤ 1.4, PTT<40 seconds and PLT>50K. Other societies such as the American Association of Blood Banks (AABB) and the C17 guideline committee have also set a platelet transfusion threshold <50K for when platelet transfusions should be considered prior to performing a lumbar puncture.
It is with this background that an important Danish population-based cohort study was published in October, 2020. Bodilsen et al. performed an analysis of the Danish nationwide medical registry to identify 64,730 patients who underwent lumbar punctures between 2008-2019. They also determined how many of these patients had a PLT<150K, an INR>1.4 or PTT>39 seconds which was their definition of a coagulopathy. They then analyzed the thirty-day risk of a spinal hematoma and secondarily the frequency of a traumatic Lumbar punctures (>300 x 106 RBC/L)
The overall risk of spinal hematoma in patients without coagulopathy was 0.2% with a 95% CI 0.16%-0.24% (99 of 49,526 LPs) vs a a risk of 0.23% in patients with a coagulopathy (95% CI 0.15%-0.34%). This difference was not statistically significant and did not increase with severity of coagulopathy. Conversely, the incidence of traumatic LPs did increase with increasing severity of coagulopathy: 36.8% with INR 1.5-2.0, 43.7% with INR 2.1-2.5 and 41.9% with INR 2.6-3.0 vs 28.2% with normal INR. Additionally, the incidence of traumatic LP was higher with prolonged aPTT (40-60 seconds) vs normal aPTT (<40 seconds): 26.3% vs 21.3%.
The incidence of spinal hematoma did not appear to increase based on the severity of thrombocytopenia in this cohort study. The incidence of spinal hematoma for patients with a PLT>150K was 0.2% (103 in 51,132) compared with 0.19% for PLT 51-100K (4 in 2065) vs 0.13% for PLT 31-50K (1 in 789) vs 0.23% for PLT 11-30K (2 in 886) vs 0% for PLT 1-10K (0 in 221). Overall, the incidence of spinal hematoma was 0.21% for PLT>50K (120 in 57,111) vs 0.16% for PLT<50K (3 in 1,896).
Results for spinal hematoma were similar for elevated prothrombin times (PT/INR) and partial thromboplastin times (aPTT): incidence of 0.24% for INR 0-1.4 (106 in 43,771) and incidence of 0.1% for INR 1.5-2.0 (1 in 957) and incidence of 0% for INR >2.1 (0 in 436). No increased risk was seen for elevated PTT as well: incidence of spinal hematoma was 0.3% for PTT 0-39 seconds (59 in 19,561) vs 0.22% for PTT 40-60 seconds (5 in 2282) and 0% for PTT >60 (0 in 322).
This blog is not advocating for performing lumbar punctures when the PLT<50K or when the INR>1.4 or the PTT>40 seconds. It is curious that the incidence of spinal hematoma was so high in this study. The incidence was about 1 in 500 for all-comers as opposed to an incidence of about 1 in 150,000 for epidural catheter placements. I still would recommend following the established guidelines set forth by ASRA and SIR; however, the study does suggest that more studies are needed to see if lumbar punctures can be safely performed at higher INR and PTT levels or lower platelet levels.
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