Comparing operative vaginal with cesarean delivery, rates of extracranial hematoma, skull fracture, facial nerve or brachial plexus injury, retinal hemorrhage, and facial or scalp laceration are lower with cesarean deliveY, and shoulder dystocia is eliminated. Importantly, however, fetal acidemia rates are not increased with operative delivery (Contag, 2010; Walsh, 2013). Intracranial hemorrhage rates are similar among newborns delivered by vacuum extraction, forceps, or cesarean delivery during labor (Towner, 1999). But, these rates are higher than among those delivered spontaneously or by cesarean delivery before labor. These authors suggest that the common risk factor for intracranial hemorrhage is abnormal labor. Werner and associates (2011), in their evaluation of more than 150,000 singleton deliveries, reported that forceps-assisted delivery was associated with fewer total neurological complications compared with vacuum-assisted or cesarean delivery. However, as a subset, subdural hemorrhage was signiicantly more frequent in both instrumental cohorts compared with neonates in the cesarean delivery group.
Comparing rotational operative delivery and second-stage cesarean delivery, maternal and neonatal morbidity rates are similar (Aiken, 2015; Bahl, 2013; Stock, 2013). For example, in their large series, Tempest and associates (2013) found similar morbidity rates among malpositioned fetuses during second-stage labor that underwent Kielland rotation, rotational vacuum extraction, or emergency cesarean delivery.
Comparing midforceps and cesarean delivery, reports of neonatal morbidity rates are from older studies and are conflicting. In the study by Towner and colleagues (1999), similar risks were reported for intracranial hemorrhage. Bashore and associates (1990) observed comparable Apgar scores, cord blood acid-base values, neonatal intensive care unit admission, and birth trauma between these two. In another study, however, Robertson and coworkers (1990) reported signiicantly higher rates of these adverse outcomes in the midforceps group. Hagadorn-Freathy and colleagues (1991) reported an increased risk for facial nerve palsy-9 percent-with midforceps delivery. In a recent report comparing low and midforceps procedures, Ducarme and coworkers (2015) found comparable morbidity rates.
Mechanisms of Acute Injury he types of fetal injury with operative delivery can usually be explained by the forces exerted. In cases of cephalohematoma or subgaleal hemorrhage, suction and perhaps rotation during vacuum extraction may lead to a primary vessel laceration. Intracranial hemorrhage may result from skull fracture and vessel laceration or from vessel laceration alone due to exerted forces. With facial nerve palsy, one of the forceps blades may compress the nerve against the facial bones. he higher rates of shoulder dystocia seen with vacuum extraction may result from the angle of traction. With the vacuum, this angle creates vector forces that actually pull the anterior shoulder into the symphysis pubis (Caughey, 2005). To explain brachial plexus injury, Towner and Ciotti (2007) proposed that as the fetal head descends down the birth canal, the shoulders may stay above the pelvic inlet. Thus, similar to shoulder dystocia at the symphysis, this "shoulder dystocia at the pelvic inlet" is overcome by traction forces but with concomitant stretch on the brachial plexus.