New data on risks of labor anesthesia in women with low platelet counts

The new research by Dr. Christopher G. Goodier of Medical University of South Carolina and colleagues "narrows the risk estimate" for complications related to spinal or epidural (neuraxial) anesthesia in women with low platelet counts (thrombocytopenia). But while the overall risk appears low, more data is needed on the risks for women with more severe reductions in platelet levels.

Is Neuraxial Labor Anesthesia Safe for Women with Thrombocytopenia?

Anesthesiologists face a "clinical dilemma" when asked to provide labor analgesia/anesthesia for women with low platelet counts. Low levels of platelets -- specialized blood cells essential for normal blood clotting -- occur in seven to ten percent of pregnancies.

The most-feared complication is spinal epidural hematoma -- a collection of blood placing pressure on the spine. To avoid this risk, anesthesiologists may hesitate to perform neuraxial anesthesia in women with low platelet counts. That's despite a lack of data on the true risks of this complication.

To clarify the risk, Dr. Goodier and colleagues analyzed an experience of 280 women in labor with low platelet counts -- less than 100,000 per square millimeter -- treated at two university hospitals. The most common cause of thrombocytopenia was pre-eclampsia, a disorder causing high blood pressure during pregnancy.

Sixty-two percent of the women received epidural and/or spinal anesthesia, despite their low platelet counts. In this relatively large experience, no cases of spinal epidural hematoma occurred.

To further refine their risk estimate, the researchers added their patients to 326 cases from previous, smaller studies. In the resulting sample of 499 patients, the estimated risk of spinal-epidural hematoma was very low -- between zero and 0.6 percent. Although detailed information on platelet counts was lacking for many women, risk appeared to be lower at higher platelet counts.

In addition to pain control during labor, a major concern is how to provide anesthesia for women with low platelet counts who require cesarean delivery. In normal-risk women, spinal or epidural anesthesia is strongly preferred, because of the higher risk of complications with general anesthesia.

In the new experience, 40 percent of women requiring cesarean section received general anesthesia. This group had lower platelet counts than women receiving epidural or spinal anesthesia. The rate of complications related to general anesthesia was substantial: 6.5 percent.

The analysis provides new insights into the rate of spinal epidural hematoma related to neuraxial anesthesia in women with low platelet counts, suggesting a risk no higher than 0.6 percent. However, there still isn't enough data to rule out a higher risk among women with lower platelet counts -- under 75,000 to 80,000 per square millimeter.

Very large studies -- with hundreds of cases at each level of platelet count -- would be needed to further clarify these risks. "Remaining uncertainties at lower platelet counts make a national 'low platelet' registry critical to a more accurate assessment of the risk of epidural hematoma and would aid in standardization of anesthesia practice," Dr. Goodier and colleagues conclude.

In a related editorial, Dr. William Camann of Brigham and Women's Hospital says it's "time to rethink old dogma" on withholding neuraxial anesthesia based on the risk of spinal epidural spinal hematoma. He writes, "One can never say 'zero risk,' but these data are suggestive that the actual risk, even for this feared complication, is low." Dr. Camann emphasizes that anesthesiologists must consider the patient's overall clinical situation -- not just platelet counts alone -- in assessing the risks versus benefits of epidural or spinal anesthesia during labor.