Retrospective analysis of the incidence of epidural haematoma in patients with epidural catheters and abnormal coagulation parameters

      Background

      Epidural haematoma is a rare but potentially catastrophic complication associated with epidural catheterization. The times of insertion and removal of epidural catheters are high-risk periods for epidural haematoma formation, especially with abnormal coagulation parameters. There is a lack of data on the incidence of epidural haematoma in patients with abnormal coagulation parameters.

      Methods

      A retrospective analysis was undertaken from 2002 to 2009 on patients with an epidural catheter. Queries were performed on the coagulation parameters for the dates of placement and removal of the catheters and on all documented epidural haematoma cases.

      Results

      During the study period, 11 600 epidural catheters were placed. In the setting of abnormal coagulation parameters, 278 (2.4%) epidural catheters were placed and 351 (3%) were removed. Two epidural haematomas occurred; both patients had epidural catheters and spinal drains placed for vascular procedures with abnormal coagulation parameters after operatation. The haematomas occurred after removal of the catheters. Based on our study, the incidence of epidural haematoma in patients with abnormal coagulation parameters is 1 in 315 patients, with the lower limit of the 95% confidence interval at 87 and the upper limit at 2597.

      Conclusions

      The risk of epidural haematoma is clearly elevated with abnormal coagulation parameters. Our data suggest that as the incidence of epidural haematoma with neuraxial access in patients with abnormal coagulation is not 100%, individual risk–benefit evaluations are warranted.

      Key words

      Editor’s key points
      • Obtaining accurate data on rare but severe complications of regional anaesthesia can be difficult.
      • This large retrospective study focused on epidural haemtomas occurring in patients with abnormal coagulation.
      • The presence of abnormal coagulation did increase epidural haematomas, but not to 100%.
      • A careful risk assessment should take into account individual factors before deciding on regional anaesthesia.
      Epidural haematoma is a rare but potentially catastrophic complication associated with epidural catheter placement and removal.
      • Cook TM
      • Counsell D
      • Wildsmith JAW
      Major complications of central neuraxial block: reporton the Third National Audit Project of the Royal College of Anaesthetists.
      The incidence of epidural haematoma in the setting of epidural catheter placement or removal is reported to be as low as 0.00055 and 0.00008%.
      • Cook TM
      • Counsell D
      • Wildsmith JAW
      Major complications of central neuraxial block: reporton the Third National Audit Project of the Royal College of Anaesthetists.
      • Ruppen W
      • Derry S
      • McQuay H
      • Moore RA
      Incidence of epidural hematoma, infection, and neurologic injury in obstetric patients with epidural analgesia/anesthesia.
      However, other more recent studies have reported a higher incidence, from 0.01 to 0.03%.
      • Bateman BT
      • Mhyre JM
      • Ehrenfeld J
      • et al.
      The risk and outcomes of epidural hematomas after perioperative and obstetric epidural catheterization: a report from the Multicenter Perioperative Outcomes Group Research Consortium.
      • Ehrenfeld JM
      • Agarwal AK
      • Henneman JP
      • Sandberg WS
      Estimating the incidence of suspected epidural hematoma and the hidden imaging cost of epidural catheterization: a retrospective review of 43,200 cases.
      • Horlocker TT
      • Wedel DJ
      • Benzon H
      • et al.
      Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation).
      Coagulopathy either from the use of anticoagulant, antiplatelet, or thrombolytic medications or from underlying medical conditions is considered one of the major risk factors of epidural haematoma formation related to epidural catheter placement or removal.
      The American Society of Regional Anesthesia (ASRA) guidelines recommend checking a coagulation panel before placing and removing epidural catheters in patients at risk for abnormal coagulation panels.
      • Horlocker TT
      • Wedel DJ
      • Benzon H
      • et al.
      Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation).
      There is controversy in the literature on the real risk of bleeding in patients with abnormal coagulation parameters.
      • Davis JJ
      • Bankhead BR
      • Eckman EJ
      • Wallace A
      • Strunk J
      Three-times-daily subcutaneous unfractionated heparin and neuraxial anesthesia: a retrospective review of 928 cases.
      • Segal JB
      • Dzik WH
      Transfusion Medicine/Hemostasis Clinical Trials Network. Paucity of studies to support that abnormal coagulation test results predict bleeding in the setting of invasive procedures: an evidence-based review.
      Clinicians are often faced with assessing benefits and risks for a patient who develops abnormal coagulation parameters while an epidural catheter is in situ. There are risks for certain patient populations with aggressive correction of coagulation abnormalities. In addition, recent literature has raised doubts about the benefits of prophylactic correction of coagulation abnormalities in reducing bleeding risk with invasive procedures.
      • Holland L
      • Sarode R
      Should plasma be transfused prophylactically before invasive procedures?.
      • Müller MC
      • Arbous MS
      • Spoelstra-de Man MA
      • et al.
      Transfusion of fresh-frozen plasma in critically ill patients with a coagulopathy before invasive procedures: a randomized clinical trial. Transfusion.
      The times of insertion and removal of epidural catheters are high-risk periods for epidural haematoma formation. It is recommended that placement and removal of epidural catheters occur with normal coagulation parameters.
      • Horlocker TT
      • Wedel DJ
      • Benzon H
      • et al.
      Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation).
      Previous studies have provided data on the overall incidence of epidural haematomas per number of epidurals performed. In order to estimate accurately the risk of epidural catheter placement or removal in patients with abnormal coagulation parameters, it is important to understand the incidence of haematoma in patients who had epidural catheters placed or removed with abnormal coagulation parameters.
      We hypothesize that all patients with abnormal coagulation parameters who have epidurals placed or removed do not develop epidural haematoma. There is a paucity of data on what percentage of patients with abnormal coagulation parameters will develop epidural haematoma. Our study aims to provide a more appropriate denominator when assessing risk in patients with abnormal coagulation parameters.

      Methods

       Definition of abnormal coagulation parameters

      Based primarily on the ASRA guidelines
      • Horlocker TT
      • Wedel DJ
      • Rowlingson JC
      • et al.
      Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (third edition).
      and our laboratory’s normal value range, the following were considered abnormal for the purpose of this study: partial thromboplastin time (PTT) >35 s, an international normalized ratio (INR) ≥1.5, and a platelet count <100,000 ml−1. Patients who had any one of these three coagulation parameters in the abnormal range were included in the study.

       Definition of cohort

      After receiving approval from the Institutional Review Board, our cohort consisted of all patients from 2002 to 2009 with abnormal coagulation parameters at the time of epidural placement or removal.

       Data analysis

      A retrospective data analysis was conducted on 11 600 patients who received epidurals from 2002 to 2009 for postoperative analgesia. We reviewed the last documented coagulation tests for patients within a 12 h period prior to the placement or removal of an epidural catheter. We then formed our cohort of 629 patients by selecting patients with abnormal coagulation parameters during epidural catheter placement or removal. Validation of the data was performed by reviewing the abnormal laboratory values and the temporal relationship with regard to epidural placement and removal in individual patient records.
      We identified patients with abnormal coagulation parameters who were on antiplatelet and/or anticoagulation medications at the time of epidural placement or removal. Our Quality and Safety database was then queried for all documented epidural haematoma cases from 2002 to 2009.
      Given that both patients in our study who developed epidural haematoma underwent vascular surgery, we also queried the percentage of vascular surgical patients among those with abnormal coagulation parameters.

       Statistical methods

      The statistical results reported in this article were calculated using Exact binomial 95% confidence interval (CI) in SAS Version 9.2 (SAS Institute Inc., Cary, NC, USA).

      Results

      Between 2002 and 2009, a total of 11 600 epidural catheters were placed for postoperative analgesia at the Massachusetts General Hospital. On average, the epidural catheters were maintained for 2.5 days (range 0–6 days). Of all epidural catheters, 5.4% (n=629; 95% CI 5.0–5.9%) were either inserted or removed in the setting of abnormal coagulation parameters. Of these, 44.2% (n=278; 95% CI 40.3–48.2%) of epidural catheters were placed and 55.8% (n=351; 95% CI 51.8–59.7%) were removed with abnormal coagulation parameters. The average age of the 629 patients with abnormal coagulation parameters was 66.97 yrs (variance 1.15 yrs). All of the 278 patients with abnormal coagulation parameters were on anticoagulant therapy at the time of catheter placement. Of the 351 patients with abnormal coagulation parameters at the time of removal, 170 were on anticoagulant therapy (Table 1).
      Table 1Medications
      MedicationNumber of patients
      PlacementRemovalTotal
      Aspirin244569
      Clopidogrel112
      Heparin s.c.18862250
      Dalteparin7815
      Warfarin62026
      Fondaparinux156
      Low-molecular weight heparin189
      Aspirin + heparin s.c.461157
      Aspirin + warfarin011
      Aspirin + clopidogrel022
      Aspirin + fondaparinux022
      Aspirin + dalteparin + heparin s.c.101
      Warfarin + heparin s.c.101
      Warfarin + dalteparin033
      Warfarin + low-molecular weight heparin011
      Dalteparin + heparin s.c.213
      Total278170448
      The average of abnormal coagulation values were as follows: INR 1.69 (range 1.5–4.4), platelet count 82 760 ml−1 (range 22 000–99 000), and PTT 43.82 s (range 35.1–84.4) (Fig. 1).
      Figure thumbnail gr1
      Fig 1Abnormal coagulation parameters. INR, international normalized ratio; PLT, platelet count×103 ml−1; PTT, partial thromboplastin time (seconds).
      Two epidural haematomas occurred in the study period. Both patients had epidural catheters and spinal drains placed for open abdominal aortic aneurysm repairs, with abnormal coagulation parameters postoperatively. The haematomas occurred after removal of the catheters. Of the patients who developed epidural haematoma, both had abnormal coagulation values at the time of removal. One patient had abnormal PTT and INR and multiple attempts at spinal drain placement for spinal cord ischaemia. The other patient was started on dalteparin after surgery in addition to warfarin as a result of a subtherapeutic INR. Of note, no epidural haematomas occurred in patients with normal coagulation parameters during the study period.
      Both patients had vascular surgery, specifically abdominal aortic aneurysm repair. Of the 629 patients with abnormal coagulation parameters, 229 patients had vascular surgery. Of the vascular surgery patients, 145 patients had open abdominal aortic aneurysm repairs. A total of seven vascular surgery patients received spinal drains, and five of these patients did not develop epidural haematomas.
      Based on our study, the incidence of epidural haematoma in patients with abnormal coagulation parameters is 1 in 315 patients with the lower limit of the 95% CI at 87 and the upper limit at 2597.

      Discussion

      There has been a strong association in the literature regarding abnormal coagulation parameters and an increased risk for epidural haematoma formation, a potentially devastating complication.
      • Horlocker TT
      • Wedel DJ
      • Benzon H
      • et al.
      Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation).
      • Davis JJ
      • Bankhead BR
      • Eckman EJ
      • Wallace A
      • Strunk J
      Three-times-daily subcutaneous unfractionated heparin and neuraxial anesthesia: a retrospective review of 928 cases.
      This risk factor has been determined largely on the basis of case series and reports. For instance, the association of heparin anticoagulation with epidural haematoma formation after lumbar puncture was reported in the 1980’s on seven spinal haematomas in 342 patients after they were anticoagulated with heparin for cerebral ischaemia following a diagnostic lumbar puncture.
      • Ruff RL
      • Dougherty Jr, JH
      Complications of lumbar puncture followed by anticoagulation.
      However, as stated in the ASRA consensus statement, it is impossible to determine conclusively the risk factors for the development of spinal haematoma in patients undergoing neuraxial blockade solely through review of the case series.
      • Horlocker TT
      • Wedel DJ
      • Benzon H
      • et al.
      Regional anesthesia in the anticoagulated patient: defining the risks (the second ASRA Consensus Conference on Neuraxial Anesthesia and Anticoagulation).
      This is because case series represent only patients with the complication and do not define those who underwent uneventful neuraxial analgesia.
      The denominator of the incidence of epidural haematoma is currently defined by the number of epidurals performed in all patients.
      • Bateman BT
      • Mhyre JM
      • Ehrenfeld J
      • et al.
      The risk and outcomes of epidural hematomas after perioperative and obstetric epidural catheterization: a report from the Multicenter Perioperative Outcomes Group Research Consortium.
      However, to ascertain accurately the risk of epidural haematoma in patients with abnormal coagulation panels, the denominator should be the number of patients who had neuraxial access with abnormal coagulation parameters.
      We undertook this study to provide a better definition of the incidence of epidural haematoma in patients undergoing epidural catheter placement who have abnormal coagulation parameters. Our study results would support abnormal coagulation parameters as a significant risk factor for epidural haematoma formation at 1 in 315, with the lower limit of the 95% CI being 87 and the higher limit being 2597.
      In our review of the 11 600 epidurals placed during the study period, we found that 629 had been either placed or removed in the setting of abnormal coagulation parameters.
      Nevertheless, there are multiple clinical situations in which patients may have develop coagulation abnormalities after placement of epidural catheters. Current practice would be to wait for these to normalize or to correct these abnormal values in a manner with products before removal of the catheter. While not specific to neuraxial access, data on other invasive procedures indicate that prophylactic correction of abnormal coagulation parameters does not reduce the risk of bleeding.
      • Holland L
      • Sarode R
      Should plasma be transfused prophylactically before invasive procedures?.
      • Müller MC
      • Arbous MS
      • Spoelstra-de Man MA
      • et al.
      Transfusion of fresh-frozen plasma in critically ill patients with a coagulopathy before invasive procedures: a randomized clinical trial. Transfusion.
      These studies specifically refer to the prophylactic administration of plasma products to correct coagulation abnormalities. However, when possible, the standard of care should be to stop an anticoagulant and wait for acceptable coagulation parameters.
      A patient with end-stage respiratory disease and rib fractures would be likely to benefit significantly from epidural analgesia.
      • Bulger EM
      • Edwards T
      • Klotz P
      • Jurkovich GJ
      Epidural analgesia improves outcome after multiple rib fractures.
      If they are anticoagulated at the time of the trauma resulting in rib fractures, for instance, it is a relative contraindication for epidural catheter placement. Our data can help in making a more informed risk–benefit evaluation for such patients.
      In our cohort, both epidural hematomas occurred in patients who had spinal drains placed. Two of the seven patients with spinal drains developed epidural hematomas. While evidence in the literature has shown that postoperative drains are not significant risk factors,
      • Kou J
      • Fischgrund J
      • Biddinger A
      • et al.
      Risk factors for spinal epidural hematoma after spinal surgery.
      it is difficult to draw a conclusion of increased risk with spinal drains based on the small number of patients in our cohort.
      Limitations of this study include that the data are from a single centre. Furthermore, the relative infrequency of epidural haematomas after neuraxial access challenges our ability to be absolutely conclusive on the incidence. Many co-morbid conditions, such as end-stage renal disease or liver disease, may influence the coagulation status of patients. Our study does not account for these disease states if they do not affect INR, PTT, or platelet count. In addition, not all patients who received epidurals had their laboratory values checked for coagulation variables. Therefore, we may have excluded some additional patients with abnormal coagulation values who never developed an epidural hematoma. Finally, there is a possibility that epidural haematomas that did not cause neurological dysfunction went undetected.
      The risk of epidural haematoma is clearly elevated with abnormal coagulation parameters. Recent literature has raised doubts on the benefits of prophylactic correction of coagulation abnormalities in reducing the risk of bleeding with invasive procedures.
      • Holland L
      • Sarode R
      Should plasma be transfused prophylactically before invasive procedures?.
      • Müller MC
      • Arbous MS
      • Spoelstra-de Man MA
      • et al.
      Transfusion of fresh-frozen plasma in critically ill patients with a coagulopathy before invasive procedures: a randomized clinical trial. Transfusion.
      Our data suggest that as the incidence of epidural haematoma with neuraxial access in patients with abnormal coagulation is not 100%, individual risk–benefit evaluations are warranted.

      Authors’ contributions

      B.T., R.P.: data collection, data analysis, wrote first draft of the paper, and edited the paper. K.M.K.: data collection, data analysis, and edited the paper. H.L.: data analysis and edited the paper. PG: study design, wrote first draft of the paper, and edited the paper.

      Declaration of interest

      None declared.

      Acknowledgements

      Collected data: Scott Nguyen, MD, Ning Jiang, and Mary E. Lau, BS.

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