ABSTRACT: In 2011, one in three women who gave birth in the United States did so by cesarean delivery (CD). Care providers must understand the trade-offs between CD and vaginal delivery (VD) and the opportunities to avoid overuse of primary CD. Cesarean delivery carries greater risks for maternal morbidity and mortality than does VD, along with risks in later pregnancies. The most common indications for primary CD include labor dystocia, abnormal fetal heart rate (FHR) tracing, fetal malpresentation, multiple gestation, and fetal macrosomia.
The latent phase of labor has been considered prolonged at longer than 20 hours and longer than 14 hours in nulliparous and multiparous women, respectively, whereas arrest disorders have been diagnosed in the absence of cervical change for 2 hours or longer in the presence of adequate uterine contractions and cervical dilation of 4 cm or greater. Current data suggest that neither protraction nor arrest should be diagnosed at less than 6 cm of dilation. Cesarean delivery for active-phase arrest in the first stage should be reserved for women at 6 cm of dilation or greater with ruptured membranes who fail to progress despite 4 hours of adequate uterine activity or women with 6 hours or more of oxytocin administration with inadequate uterine activity and no cervical change.
Parity, delayed pushing, epidural analgesia, maternal body mass index, birth weight, occiput posterior position, and fetal station at complete dilation can all affect the length of the second stage. For each hour of the second stage, the chance for spontaneous VD decreases. Before diagnosing arrest of labor, 2 hours or more of pushing in multiparous women and 3 hours or more in nulliparous women should be allowed. Operative VD and manual rotation of the fetal occiput for malposition could also reduce the CD rate. Operative VD rates have decreased significantly in the past 15 years because physicians are not being trained in forceps techniques. With malposition, manual rotation of the fetal occiput is a reasonable intervention before operative VD or CD.
The second most common indication for primary CD is an abnormal or indeterminate FHR tracing. Category III FHR tracings require intervention, and category I FHR tracings are normal and do not require intervention other than ongoing assessment and monitoring. However, most intrapartum FHR tracings are category II, with their wide spectrum of patterns that require evaluation, surveillance, corrective measures, and reevaluation. They account for most CDs for “nonreassuring” fetal status. Scalp stimulation to elicit FHR acceleration provides reassurance that the fetus is not acidotic. Amnioinfusion with normal saline can resolve variable FHR decelerations. Fetal heart rate decelerations lasting longer than 2 minutes but less than 10 minutes often require intervention and may suggest other complications. Intrapartum fetal scalp sampling is rarely done because of its invasive nature, the narrow clinical presentations for which it is helpful, and the need for regulatory measures to maintain bedside testing availability. Use of supplemental oxygen, intravenous fluid bolus, and tocolytic agents without a subsequent change in FHR patterns is not an indication for CD.
Frequency of induction of labor (IOL) has increased with the increased CD rate. At less than 41 weeks’ gestation, IOL should be performed on the basis of maternal/fetal indications. Induction of labor at 41 weeks or later should be performed to reduce the risks of CD and perinatal morbidity and mortality. Use of cervical ripening methods leads to lower rates of CD than IOL without cervical ripening. Nonintervention in the latent phase when the FHR tracing is reassuring and maternal/fetal statuses are stable can reduce the risk for CD. Cesarean delivery for failed IOL in the latent phase can be avoided by allowing up to 24 hours or longer in the latent phase and using oxytocin for 12 to 18 hours after membrane rupture before deeming the induction a failure.
Less common indications for CD are fetal malpresentation, macrosomia, multiple gestation, and maternal infection. External cephalic version (ECV) for fetal malpresentation is likely underused, and most patients with a successful ECV will have a VD. External cephalic version should be done whenever possible and may be enhanced using regional analgesia. Fetal presentation should be assessed beginning at 36 weeks’ gestation to allow for ECV to be offered. Suspected fetal macrosomia is rarely an indication for CD. Cesarean delivery should be limited to estimated fetal weights of 5000 g or greater and 4500 g or greater in women without diabetes and with diabetes, respectively. Ultrasonography for estimating fetal weight in the third trimester should be used only with clear indications. Women with cephalic/cephalic-presenting or cephalic-presenting/non–cephalic-presenting twins should be counseled to attempt VD. In women with a history of herpes simplex virus, acyclovir administration may prevent genital herpetic outbreaks requiring CD, and women with a history of genital herpes should be offered oral suppressive therapy within 3 to 4 weeks of anticipated delivery and definitely at 36 weeks’ gestation or later.
Research will require a wide range of evidence-based approaches to assess changes in individual practice patterns, development of management guidelines from various organizations, implementation of systemic approaches at organizational and regional levels, and tort reform.