Nulliparous women who request pain relief early in labor may be better off receiving neuraxial analgesia than systemic opioid analgesia, according to investigators of a recently published, randomized trial.
Of 728 women who had spontaneous labor or spontaneous rupture of membranes, those who received intrathecal fentanyl when cervical dilation was less than 4 cm did not face an increased risk of having a cesarean section and had a shorter duration of labor, compared with those who received systemic hydromorphone early in labor.
Women who received neuraxial analgesia also reported better pain control, according to Cynthia A Wong, M.D., and her colleagues at Northwestern University in Chicago.
The findings show women who request pain relief early in spontaneous labor “can receive neuraxial analgesia at that time without adverse consequences,” the researchers said.
Women who request analgesia early in labor frequently receive systemic opioid analgesia, in keeping with the American College of Obstetricians and Gynecologists recommendation that epidural anesthesia be delayed, when feasible, until cervical dilation is at least 4-5 cm; other forms of analgesia should be used until that time.
Systemic opioid analgesia is often incomplete, however, and has potential maternal and fetal side effects, including neonatal and maternal respiratory depression (N. Engl. J. Med. 2005;352:655-65).
Laura Goetzl, M.D., who helped write ACOG's 2002 Practice Bulletin on Obstetric Analgesia and Anesthesia, said in an interview that the new findings present “another option” for prolonging the time to epidural.
“This is saying, instead of giving a higher dose of [systemic] narcotics to get women further along [until epidural administration], we can give them a smaller dose right into the spinal cord,” said Dr. Goetzl of the Medical University of South Carolina, Charleston.
The investigators studied the analgesia techniques at Northwestern's Prentice Women's Hospital from November 2000 to December 2003. Patients who requested analgesia when cervical dilation was less than 4 cm were randomized (nonblinded) to intrathecal or systemic analgesia.
The median dilation for both groups at the first analgesia request was 2 cm.
Analgesia in the intrathecal group was initiated using a combined spinal-epidural technique. Intrathecal fentanyl (25 mcg) was injected, an epidural catheter sited, and an epidural test dose administered.
When the patients in the intrathecal group made a second request for pain control, epidural analgesia was initiated.
Patients in the systemic group received 1 mg hydromorphone IM and 1 mg IV. Epidural analgesia was initiated in patients who were at least 4 cm dilated at their second request for pain control (otherwise hydromorphone was repeated), or at their third analgesia request—regardless of dilation.
Epidural analgesia was maintained in both groups until delivery, the investigators said.
The cesarean rate was not significantly different between the two groups (18% in the intrathecal group and 21% in the systemic group); nor was there a significant difference in the rate of instrumental vaginal delivery.
The median time from initial analgesia to complete dilation was significantly shorter after intrathecal analgesia than after systemic analgesia (295 vs. 385 minutes), even after investigators adjusted for cervical dilation at the time of initial anesthesia.
Women who received intrathecal analgesia also had a shorter time to vaginal delivery (398 vs. 479 minutes) and significantly lower average pain scores between the first and second analgesia requests. The incidence of 1-minute Apgar scores below 7 also was significantly lower in this group (17% vs. 24%).
Fetal deceleration occurred more commonly within 30 minutes of intrathecal opioid analgesia than after systemic analgesia. However, the incidence of nonreassuring fetal heart rate “was low, did not differ between groups, and did not result in any adverse neonatal outcome,” the investigators said.