Operative deliveries are vaginal deliveries accomplished with the use of a vacuum device or forceps. Once either is applied to the fetal head, outward traction generates forces that augment maternal pushing to deliver the fetus vaginally. The most important function of both devices is traction. In addition, however, forceps may also be used for rotation, particularly from occiput transverse and posterior positions.
The precise frequency of operative vaginal delivery in the United States is unknown. According to the birth certificate data from the National Vital Statistics Report, forceps- or vacuum-assisted vaginal delivery was used for 3.6 percent of births in the United States in 2010. According to Yeomans (2010), the vacuum-to-forceps delivery ratio is 4:1. Figure 29-1 depicts the decline in the rates of this type of delivery since 1990. In general, operative vaginal delivery attempts are successful. In the United States in 2006, only 0.4 percent of forceps trials and 0.8 percent of vacuum extraction attempts failed to result in vaginal delivery (Osterman, 2009).
Decline in operative vaginal delivery rates, 1990–2010. (From Martin, 2012.)
If it is technically feasible and can be safely accomplished, termination of second-stage labor by operative vaginal delivery is indicated in any condition threatening the mother or fetus that is likely to be relieved by delivery. Some fetal indications for operative vaginal delivery include nonreassuring fetal heart rate pattern and premature placental separation. In the past, forceps delivery was believed to be somewhat protective of the fragile preterm infant head. Subsequent studies, however, reported no significant differences in outcomes for neonates who weighed 500 to 1500 g between those delivered spontaneously and those delivered by outlet forceps (Fairweather, 1981; Schwartz, 1983).
Some maternal indications include heart disease, pulmonary injury or compromise, intrapartum infection, and certain neurological conditions. The most common are exhaustion and prolonged second-stage labor. For nulliparas, the latter is defined as > 3 hours with or > 2 hours without regional analgesia (American College of Obstetricians and Gynecologists, 2012). In parous women, it is defined as > 2 hours with and > 1 hour without regional analgesia.
Operative vaginal delivery should generally be performed from either a low or outlet station. Additionally, forceps or vacuum delivery generally should not be used electively until the criteria for an outlet delivery have been met. In these circumstances, operative vaginal delivery is a simple and safe operation, although with some risk of maternal lower reproductive tract injury (Yancey, 1991). Moreover, there is no evidence that use of prophylactic operative delivery is beneficial in the otherwise normal delivery.
Classification and Prerequisites
The American College of Obstetricians and Gynecologists (2012) classifies operative vaginal deliveries as summarized in Table 29-1. It emphasizes that ...