Patient characteristics including age, American Society of Anesthesiologists class, emergent nature of surgery, body mass index, coexisting conditions predisposing to thrombocytopenia (gestational thrombocytopenia, preeclampsia, idiopathic thrombocytopenic purpura, and hemolysis, elevated liver enzymes, and low platelet count syndrome), and anesthetic technique were identified and recorded.
Thrombocytopenic obstetric patients receiving neuraxial techniques were stratified into predefined categories based on the preplacement platelet count.
The platelet ranges were defined as 0 to 49,000 mm.
Patients who underwent surgical evacuation of an epidural hematoma within 6 weeks of receiving a neuraxial technique, regardless of platelet count, were identified by administrative billing codes.
Although there is no consensus on the acceptable platelet count required to safely perform neuraxial techniques, recent literature suggests that lower thresholds may be safe in pregnant women compared with the general population.
There are limited data suggesting that epidural hematomas in obstetric patients appear to be rare, possibly due to the physiologic hypercoagulability of pregnancy and the generally high compliance of the epidural space in young parturients.
The authors performed a retrospective cohort study using the Multicenter Perioperative Outcomes Group database to identify thrombocytopenic parturients who received a neuraxial technique and to estimate the risk of epidural hematoma.
For centers not reporting administrative billing codes, all operative episodes not typically associated with obstetric care (dilation and curettage for retained placenta or tubal ligation) within 6 weeks of receiving a neuraxial technique were manually reviewed to identify decompressive laminectomies.
For operative episodes identified in the database suggestive of decompressive laminectomy, individual medical charts were manually reviewed in detail to confirm the performance of this surgery.
A combination of administrative billing codes and free text queries for relevant phrases, including , was used to identify possible obstetric neuraxial procedures.
The complete list of query terms is found in appendix 2.