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Neuraxial Anesthesia in Parturients with Low Platelet Counts

Bernstein, Jeffrey MD; Hua, Betty MD; Kahana, Madelyn MD; Shaparin, Naum MD; Yu, Simon MD; Davila-Velazquez, Juan MD

doi: 10.1213/ANE.0000000000001312
Obstetric Anesthesiology: Brief Report

The obstetric anesthesiologist must consider the risk of spinal–epidural hematoma in patients with thrombocytopenia when choosing to provide neuraxial anesthesia. There are little data exploring this complication in the parturient. In this single-center retrospective study of 20,244 obstetric patients, the incidence of peripartum thrombocytopenia (platelet count <100,000/mm3) was 1.8% (368 patients). Of these patients, 69% (256) received neuraxial anesthesia. No neuraxial hematoma occurred in any of our patients. The upper 95% confidence limit for spinal–epidural hematoma in patients who received neuraxial anesthesia with a platelet count of <100,000/mm3 was 1.2%.

Published ahead of print May 6, 2016

From the *Department of Anesthesiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; and Department of Anesthesiology, Stony Brook University Medical Center, Stony Brook, New York.

Accepted for publication February 29, 2016.

Published ahead of print May 6, 2016

Funding: None.

The authors declare no conflicts of interest.

Reprints will not be available from the authors.

Address correspondence to Juan Davila-Velazquez, MD, Montefiore Medical Center/AECOM, 1825 Eastchester Rd., Bronx, NY 10461. Address e-mail to judavila@montefiore.org.

Neuraxial anesthesia is the most effective modality for labor analgesia and the standard of care for most cesarean deliveries. For the parturient with thrombocytopenia, the risk of general anesthesia must be balanced with the risk of neuraxial hematoma, a risk enhanced by decreased platelet number, function, or both.

Mild thrombocytopenia as defined by a platelet count of between 100,000 and 150,000/mm3 occurs with an estimated peripartum frequency of 6.4%.1 Thrombocytopenia, defined as a platelet count of <100,000/mm3 platelets, is estimated to occur in 1% of parturients.2 Primary hemostatic function can be compromised by decreased numbers of platelets with preserved function, as observed in patients with idiopathic thrombocytopenic purpura or gestational thrombocytopenia,3 and by impaired platelet function as observed in some patients with thrombocytopenia associated with hypertensive disorders in pregnancy. Studies evaluating platelet function in pre-eclamptic parturients using thromboelastography and a platelet function analyzer have shown preservation of hemostatic function with platelet counts as low as 54,000/mm3.3–5 It has been suggested by a number of authors4–7 that neuraxial anesthesia is safe in the parturient if the platelet count is higher than 75,000/mm3. Tanaka et al.3 suggested a lower limit of 50,000/mm3 platelets before neuraxial anesthesia is considered unsafe, excluding pre-eclamptic patients.

The purpose of our retrospective study was to determine the incidence and etiology of thrombocytopenia in a large data set of parturients at a single center, describe the incidence of spinal–epidural hematoma after neuraxial anesthesia in the thrombocytopenic patient, and estimate the upper 95% confidence limit of the incidence of neuraxial hematoma after neuraxial anesthesia using data from our institution and after combining our data with previously published data.

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METHODS

After approval from our IRB, the need for written informed patient consent was waived. The patented hospital software program, Clinical Looking Glass, was used to identify parturients who delivered at our hospital between September 1, 2009, and September 1, 2013, with a documented platelet count of <100,000/mm3 at admission and up until 5 days after delivery. At our institution, we obtained a complete blood count, including a platelet count, on admission to the labor and delivery suite. Two investigators performed a detailed review of the medical record of all included study subjects. We recorded the etiology of the thrombocytopenia, the type of anesthetic technique (epidural, spinal, general, or no anesthesia), the mode of delivery (vaginal or cesarean delivery), and any major neurologic and anesthetic complications during hospitalization. We also determined whether platelet counts of ≤100,000/mm3 were known before initiation of neuraxial anesthesia, as documented on the anesthesia preoperative evaluation and confirmed by timed laboratory results in the medical record.

The upper limit of the 95% confidence interval (CI) for the incidence of neuraxial hematoma was calculated using the Rule of 3 and the formula R = 1 − [(0.05)^(1/N)]. R is an estimate of the upper limit of the 95% CI for the risk of peripartum epidural hematoma and N is the number of subjects without such an event in the cohort. We estimated the upper bound of risk twice, first using the number of patients from our cohort and second by pooling the patients together from previously published studies.

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RESULTS

During the study period, 20,244 parturients were identified from the database, of whom 368 (1.8%; 95% CI, 1.6%–2.0%) had platelet counts of ≤100,000/mm3 during the peripartum period. The most common cause of thrombocytopenia, before or after delivery, was gestational thrombocytopenia (Table 1). In 256 parturients, platelet counts were known to be low before anesthetic management decisions, including placement of a neuraxial anesthetic. In 112 patients, the low platelet count was identified only after neuraxial anesthesia placement and within 24 hours after delivery.

Table 1

Table 1

Of the 256 parturients with low platelet counts identified before delivery, 151 (59%) received neuraxial anesthesia; 94% (105/112) of the patients in whom thrombocytopenia was unknown at the time of placement, but diagnosed after delivery, received neuraxial anesthesia. Approximately 60% of thrombocytopenic parturients who received neuraxial anesthesia had an epidural or a combined spinal–epidural technique. Forty-four percent of the patients with thrombocytopenia of <100,000/mm3 underwent cesarean delivery (at our institution, the overall cesarean delivery rate is approximately 30%). There were no neurologic complications in any of the patients who received a neuraxial anesthetic.

We calculated the 95% risk estimate by combining our results with the 4 other studies describing neuraxial anesthetics in thrombocytopenic parturients. Before the recent publication of the study by Goodier et al.7, 326 total cases of neuraxial anesthesia were reported in small-to-moderately sized studies.3,8,9 Combining the patients from Goodier et al.7 (173) and the patients in the current study (256) to these patients resulted in a final composite sample size of 755. No patient experienced a spinal–epidural hematoma, a zero numerator. The upper limit of the 95% CI for the risk of spinal–epidural hematoma from our study of 256 patients was 0.012 or 1.2% and of all cohorts together was 0.004 or 0.4%. Given the very few patients with platelet counts of <50,000 mm3, meaningful statistical analysis for this group is not possible.

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DISCUSSION

The major concern of the anesthesiologist in placing neuraxial anesthesia in a patient with thrombocytopenia is an epidural or spinal hematoma. The risk of epidural hematoma must be weighed against the risk of general anesthesia. The only complication observed at our institution attributable to general anesthesia in the obstetric population during this time period was a case of dental injury in a patient who did not have thrombocytopenia. No mortality in thrombocytopenic patients receiving general anesthesia was reported. The development of a neuraxial hematoma after the placement of a neuraxial block is rare and has been estimated at 1:150,000 after epidural and 1:220,000 after placement of a spinal anesthetic in the general population.10 In the obstetric population, the incidence of neuraxial hematoma is estimated at 1:168,000 after the administration of epidural analgesia.9 The incidence of hematoma after spinal anesthesia in the obstetric patient is unknown.

To the best of our knowledge, there are no confirmed case reports of hematomas after neuraxial anesthesia in parturients with thrombocytopenia, absent clinical signs of coagulopathy, abnormal bruising, or bleeding. There are 4 previous major studies in parturients that categorized a subset of patients with a platelet count of <100,000/mm3. The studies by Beilin et al.,9 Frenk et al.,11 Tanaka et al.,3 and Goodier et al.7 included 80, 177, 75, and 173 patients, respectively. Overall, there were no reports of neurologic sequelae secondary to the initiation of neuraxial anesthesia in any of these data sets. The incidence of platelet count <100,000/mm3 was 80 of 15,919 (0.50%; 95% CI, 0.30%–60%) in the study by Beilin et al.9 and 252 of 52,000 (0.54%; 95% CI, 0.47%–59%) in the study by Goodier et al.7 The overall incidence of thrombocytopenia was not reported in study by Frenk et al.11 The study by Tanaka et al.3 excluded parturients with pre-eclampsia; hence, the true incidence is not known. Our incidence of thrombocytopenia (1.8%) was almost 4 times more than the incidence found in previous studies; this may be because of a greater number of high-risk parturients with pre-eclampsia. In the studies by Beilin et al.,9 Frenk et al.,11 Tanaka et al.,3 and Goodier et al.,7 neuraxial anesthesia was performed in 65%, 96%, 63%, and 63%, respectively, of thrombocytopenic patients. We performed neuraxial blocks on 68% (256/368) of patients with thrombocytopenia, a rate similar to that described by other investigators.3,7,9

Beilin et al.9 and Goodier et al.7 recommended evaluation of the risk–benefit ratio for each individual before initiation of neuraxial anesthesia. No previously published study has had a large enough population to determine the safety of neuraxial anesthesia placement in parturients with platelet counts <100,000/mm3.

Similar to the practice patterns described by Beilin et al.,12 most of our anesthesiologists felt comfortable placing neuraxial anesthesia in otherwise healthy parturients with stable platelet counts between 80,000/mm3 and 100,000/mm3, typically observed in patients with gestational thrombocytopenia. However, additional concern is present in patients with pre-eclampsia in whom both the number of platelets may decrease precipitously and the quality of the platelets may also be impaired.13–15 Ideally, in these patients, a test of platelet function such as thromboelastography is performed before central neuraxial block placement.

Our study was limited by its retrospective nature. The anesthetic management was dictated by the individual attending anesthesiologists. Tests of platelet function were not consistently performed. Additional large studies in pregnant patients with thrombocytopenia and with platelet dysfunction who receive neuraxial anesthesia will help to build on the existing database to further support safe recommendations and limitations of neuraxial techniques in the parturient with low platelet counts.

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DISCLOSURES

Name: Jeffrey Bernstein, MD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Jeffrey Bernstein has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.

Name: Betty Hua, MD.

Contribution: This author helped design the study, conduct the study, and analyze the data.

Attestation: Betty Hua has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Madelyn Kahana, MD.

Contribution: This author helped write the manuscript.

Attestation: Madelyn Kahana approved the final manuscript.

Name: Naum Shaparin, MD.

Contribution: This author helped write the manuscript.

Attestation: Naum Shaparin approved the final manuscript.

Name: Simon Yu, MD.

Contribution: This author helped write the manuscript.

Attestation: Simon Yu approved the final manuscript.

Name: Juan Davila-Velazquez, MD.

Contribution: This author helped write the manuscript.

Attestation: Juan Davila-Velazquez approved the final manuscript.

This manuscript was handled by: Cynthia A. Wong, MD.

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