DENA TOWNER, MARY AMES CASTRO, ELAINE EBY-WILKENS AND WILLIAM M. GILBERT
Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, University of California Davis Medical Center, Sacramento, California, and Department of Obstetrics and Gynecology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts
N. Engl. J. Med., 341: 1709–1714, 1999
The risk of serious neonatal injury associated with vacuum extraction has been controversial. The extent of the risk for major injuries in infants delivered by vacuum extraction or other operative techniques is unknown. This study was designed to determine the incidence of rare neonatal disorders and their association with various modes of delivery, particularly vacuum extraction.
Using a California database, 583,340 live-born singleton infants born to nulliparous women from 1992 to 1994 and weighing between 2500 and 4000 g were identified. One-third were delivered by operative techniques. The mode of delivery and morbidity were evaluated.
The death rate did not differ significantly between infants delivered spontaneously and those delivered by vacuum extraction, forceps, or vacuum extraction combined with forceps delivery. Significantly more deaths occurred among infants delivered by cesarean section than among those delivered spontaneously. The death rate was the same for infants born by cesarean delivery during labor and for those born by cesarean delivery with no labor.
Intracranial hemorrhage occurred in 1 of 860 infants delivered by vacuum extraction, 1 of 684 delivered with the use of forceps, 1 of 907 delivered by cesarean section during labor, 1 of 2750 delivered by cesarean section with no labor, and 1 of 1900 delivered spontaneously. Compared with infants born by spontaneous vaginal delivery, infants delivered by vacuum extraction had significantly higher rates of subdural or cerebral hemorrhage, brachial plexus injury, convulsions, CNS depression, and mechanical ventilation. The rates of intraventricular hemorrhage, subarachnoid hemorrhage, facial nerve injury, and feeding difficulty did not differ significantly between the two groups.
Infants delivered with forceps had significantly higher rates of subdural or cerebral hemorrhage, facial nerve injury, brachial plexus injury, and mechanical ventilation than did infants delivered spontaneously. As compared with vacuum extraction, forceps delivery was significantly associated only with facial nerve injury. Compared with spontaneous delivery, vacuum extraction combined with forceps delivery was associated with higher rates of subdural or cerebral hemorrhage, intraventricular hemorrhage, subarachnoid hemorrhage, facial nerve and brachial plexus injury, CNS depression, convulsions and mechanical ventilation.
When cesarean delivery during labor was compared with vacuum extraction, the cesarean delivery was associated with significantly higher rates of convulsions, feeding difficulty, and mechanical ventilation but not with higher rates of intracranial hemorrhage.
The rate of intracranial hemorrhage is higher among infants delivered by vacuum extraction, forceps, or cesarean section during labor than among infants delivered spontaneously. The incidence of intracranial hemorrhage in infants delivered by cesarean section before the onset of labor is not higher than the incidence among infants delivered spontaneously. When spontaneous delivery after labor is not possible, the obstetrician must decide whether to perform an assisted vaginal delivery or cesarean section. Successful vaginal delivery with the use of either vacuum or forceps is not riskier in regard to neonatal intracranial hemorrhage than is cesarean delivery during labor. This finding suggests that a portion of the morbidity thought to be a function of operative vaginal delivery may actually have occurred during labor.
Both of these studies highlight the fact that operative vaginal delivery is associated with increased complications both for the mother and the neonate. As such, it is important to promote and enhance the possibility of spontaneous vaginal delivery while decreasing the risk of operative vaginal delivery. The link between epidural analgesia and operative vaginal delivery is not a recent one. In 1969, Catton examined 771 parturients who received epidural analgesia during their labor. 1 The incidence of forceps delivery was 85% for multiparous patients and 97% for primiparous patients. Hawkins et al. performed a case control study to evaluate the association between epidural analgesia and forceps delivery. 2 Epidural analgesia was a risk factor for instrumental delivery, but so was gestational age greater than 41 wk, second stage greater than 2 hr, occiput posterior or transverse fetal presentation, and previous cesarean section.
How might epidural analgesia be linked to operative vaginal delivery? In a series of three studies, Chestnut et al. demonstrated that comparable analgesia can be achieved with lower concentrations of local anesthetics in combination with opioid. 3–5 By decreasing the concentration of local anesthetic, the incidence of motor block as well as the incidence of operative vaginal delivery decreased. Motor block accompanying epidural analgesia increased the risk of an operative delivery. All anesthesiologists should use the lowest concentration of local anesthetic in combination with opioid to provide labor analgesia so as to decrease motor block and operative vaginal delivery. In doing so, the anesthesiologist is also decreasing the risk of rehospitalization for the mother and of intracranial hemorrhage for the neonate.
Robert Gaiser M.D.
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2. Hawkins JL, Hess KR, Kubicek MA. A reevaluation of the association between instrument delivery and epidural analgesia. Reg Anesth 1995; 20:50–6.
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4. Chestnut DH, Owen CL, Bates JN, et al. Continuous infusion epidural analgesia during labor: a randomized, double-blinded comparison of 0.0625% bupivacaine/0.0002% fentanyl versus 0.125% bupivacaine. Anesthesiology 1988; 68:754–9.
5. Chestnut DH, Laszewshi LJ, Pollack KL, et al. Continuous epidural infusion of 0.0625% bupivacaine-0.0002% fentanyl during the second stage of labor. Anesthesiology 1990; 72:613–8.