Injecting spinal-epidural analgesia in early labor does not increase cesarean delivery rates and provides better pain relief and a shorter duration of labor than systemic opioid analgesia, according to an article by Northwestern University researchers published in the Feb. 17 issue of The New England Journal of Medicine. Epidural injections are administered into the space between the wall of the spinal canal and the sheath covering the spinal cord and anesthetize the abdominal, genital and pelvic areas. Spinal injections are administered into the fluid surrounding the spinal cord.
Previous research has suggested that epidural analgesia initiated early in labor – when the cervix is dilated less than 4 centimeters – is associated with an increased risk for cesarean delivery.
Based on that research, the American College of Obstetricians and Gynecologists recommended that epidural analgesia be delayed in women who have not previously given birth until their cervix dilates to 4 to 5 centimeters and that other forms of analgesia, for example, systemic opioid analgesia, be used until that time.
However, it is unclear whether increased risk for cesarean delivery is due to neuraxial [spinal or epidural] analgesia or can be explained by other factors, said Cynthia A. Wong, M.D., associate professor of anesthesiology at Northwestern University Feinberg School of Medicine, who led the study. Wong also is an anesthesiologist at Northwestern Memorial Hospital.
“Systemic opioid analgesia is often incomplete and has potential maternal and fetal side effects, including neonatal and maternal respiratory depression, especially when spinal or epidural opioids are administered concomitantly,” Wong said.
The Northwestern study examined 750 full-term, nulliparous (no previous births) women in spontaneous labor, with cervical dilation less than 4 centimeters.
Participants were randomized to receive spinal fentanyl or systemic hydromorphone (a morphine-like drug) at their first request for analgesia. Epidural analgesia was administered in the spinal group at their second request for analgesia, and in the systemic group, when the cervix had dilated to 4 centimeters or greater, or at the third request for analgesia. Rate of cesarean delivery was the primary outcome.
Wong and colleagues found that the rate of cesarean delivery was not significantly different between the groups – 18 percent in the spinal group versus 21 percent in the systemic group.
Moreover, the median time from initiation of analgesia to complete dilation was 295 minutes in the epidural group versus 385 minutes in the systemic group; vaginal delivery was significantly shorter (398 minutes versus 479 minutes) and self-reported pain scores were significantly lower after spinal-epidural analgesia.
The lack of association between early labor neuraxial analgesia and an increased cesarean delivery rate suggests that request for analgesia, or greater analgesia use, may be markers for other risk factors for cesarean section, Wong said.
Another clinically important finding of the Northwestern study was that duration of the first stage of labor following epidural administration of analgesia was shorter by approximately 80 minutes. Previous studies have found that epidural analgesia compared to systemic opioid analgesia was associated with a prolonged first stage of labor.
Wong’s co-authors on this study were Barbara M. Scavone, M.D.; Robert J. McCarthy, PharmD; John T. Sullivan, M.D.; Nathaniel T. Diaz, M.D.; Edward Yaghmour, M.D.; R-Jay L. Marcus, M.D.; Saadia S. Sherwani, M.D. Michelle T. Sproviero, M.D.; Roshani Patel; Carmen Robles; and Sharon Grouper, anesthesiology; and Alan M. Peaceman, M.D., obstetrics and gynecology.
The department of anesthesiology at Feinberg supported this study.