SUMMARY:

Compared to vaginal delivery, cesarean delivery has greater risk of maternal severe morbidity and mortality. The international healthcare community has defined an ideal prevalence of cesarean delivery to be between 10% to 15%. Currently in the United States, one in three women give birth by cesarean delivery.

Several approaches have been used to decrease the prevalence of cesarean delivery. One of the main strategies includes the prevention of primary cesarean delivery, which decreases long-term risks and lowers the repeat cesarean delivery rate.  ACOG summarizes recommendations to safely avoid the first cesarean section.

Most common indications for cesarean delivery (starting with most frequent) include

• Labor dystocia
• Abnormal or indeterminate fetal heart rate tracing
• Fetal malpresentation
• Multiple gestation
• Suspected fetal macrosomia

Dystocia in the First Stage of Labor

• Consortium on Safe Labor: Contemporary labor data in the United States  
• In a multi-center retrospective study, Zhang et al. reviewed the data of more than 60,000 normal deliveries from 2002 to 2008, constructing average labor curves showing that
  • Cervical dilation was slower until 6cm | Previously 4cm as described by Friedman
  • Time to progress from 4 to 10 cm was significantly higher than previously described

Latent phase

• Latent phase, defined as prior to 6 cm, is no longer a criterion for cesarean section
• Augmentation is recommended
  • Most patients will experience active labor spontaneously or after intervention (amniotomy and or oxytocin)
• Allowing for longer duration of latent phase may avoid cesarean sections for failed induction, defined as rupture of membranes and oxytocin for 12 to 18 hours without cervical change

ACOG states that

Because they are contemporary and robust, it seems that the Consortium on Safe Labor data, rather than the standards proposed by Friedman, should inform evidence-based labor management

Active phase

• Dilation of at least 6 cm should be considered the threshold for active phase
• Cesarean delivery for arrest of dilation should be reserved for patients with the following criteria
  • ≥6 cm dilated with ruptured membranes and
    • ≥4 hours of adequate uterine contractions and no cervical change or
    •  ≥6 hours of oxytocin without adequate uterine activity and no cervical change

Note: There is an association between duration of first stage of labor and chorioamnionitis, but causality is unclear

Dystocia in the Second Stage of Labor

• Longer duration of second stage of labor may be associated with adverse neonatal outcomes but risk appears to be low and incremental
• Arrest of labor in the second stage diagnosis: No descent while pushing for 2 hours in multiparous and 3 hours in nulliparous patients without epidural anesthesia
  • Individualizing care and allowing for longer durations in certain patients who have received an epidural may be appropriate
• Operative vaginal delivery
  • Safe alternative to cesarean when performed by skilled physicians
  • Encourage training, and ongoing maintenance, of practical skills
• Manual rotation of the fetal occiput
  • Reduces cesarean rates whether successful or attempted
• Frequently assess fetal position in second stage of labor, especially if there is abnormal fetal descent

Abnormal or Indeterminate Fetal Heart Rate Tracings 

Category III

• Category III tracings are associated with fetal acidemia, cerebral palsy and encephalopathy and require expedient intervention
• If intrauterine resuscitation (eg. repositioning, stopping oxytocin, assessment of hypotension) fails to improve the tracing, deliver rapidly and safely

Category II

• Category II is common and comprises a diverse spectrum of patterns
  • Minimal variability, prolonged decelerations or recurrent late decelerations require intervention
• Initiate intrauterine resuscitation with evaluation for other causes such as umbilical cord prolapse
• Recurrent variable decelerations are not themselves pathologic but may lead to fetal acidemia
• Scalp stimulation may help assess fetal acid-base status in presence of abnormal or indeterminate tracing

Note: Use of an algorithm, such as the Shields algorithm or Clark algorithm, may help guide management of Category II tracings (see ‘Primary Sources – Learn More’ below)

Fetal Malpresentation

• Assess presentation beginning at 36w0d
• External cephalic version (ECV) should be offered whenever possible at term | Success may be enhanced by terbutaline and regional anesthesia
• One study showed an increased rate of successful ECV in patients that received regional anesthesia than ones that did not (79% success with anesthesia vs 56% success without)
• The combination of anesthesia and tocolysis is associated with increased rates of success ECV, cephalic presentation in labor, and vaginal delivery

Twin Gestation 

• Perinatal outcomes are not improved by cesarean if the first twin is in cephalic
• Cephalic/cephalic or cephalic/non-cephalic should be counseled to attempt vaginal delivery
• Residents should be trained to perform twin deliveries and second breech extraction

Suspected Fetal Macrosomia 

• Limit cesarean delivery to
  • Without diabetes: Estimated fetal weight ≥5000 grams
  • With diabetes: Estimated fetal weight ≥4500 grams
• Third trimester ultrasonography fetal weight estimate should be used sparingly and with clear indications
  • Patients should be counseled that the ultrasound estimation of fetal weight in late gestation is inaccurate
  • Weights ≥5000 grams are rare

Clinical Scenarios that May Prevent Avoidable Cesarean Delivery 

Elective Induction of Labor at 39 weeks

• The ARRIVE trial was an RCT comparing elective induction at 39 weeks with expectant management in low-risk nulliparous patients
• Primary fetal outcome: No statistical difference in perinatal mortality and severe morbidity
• Pre-specified major maternal outcome
  • Cesarean delivery rate was significantly lower in the induction of labor group (18.6% versus 22.2%)

Note: Allow 24 h or more in the latent phase before diagnosing failed induction | Rupture of membranes and oxytocin for 12 to 18 hours must be present prior to diagnosis of failed induction

Excessive Maternal Weight Gain

• Optimal weight gain during pregnancy varies by pre-pregnancy BMI
  • BMI <18.5: Weight gain between 18 to 40 lbs
  • BMI 18.5 to 24.9: Weight gain between 25 to 35 lbs
  • BMI 25.0 to 29.9: Weight gain between 15 to 25 lbs
  • BMI >30: Weight gain between 11 to 20 lbs
• Weight gain above the recommended limits is associated with increased rates of cesarean delivery and adverse outcomes
• Counseling about appropriate weight gain, diet and exercise is appropriate throughout pregnancy to prevent excessive weight gain

Herpes Simplex Virus

• Recommendation is for prevention of outbreaks at time of delivery in women with history of genital herpes
• Oral antiviral should be initiated within 3 to 4 weeks of delivery, at the latest starting at 36 weeks

Organizational level interventions

• Changing local culture and attitudes using multifaceted interventions
  • Provider audits
  • Feedback or huddles
  • Second opinions
• Continuous labor and delivery support | One-on-one support (such as doula) improves patient satisfaction and reduces the rate of cesarean delivery
• Medico-legal pressures, tort reform
• Provide better knowledge base for clinical decisions

KEY POINTS:

• Prolonged duration of latent phase of labor is not an indication for cesarean delivery
• Cervical dilation of 6 cm should be the threshold for active phase of labor
• Arrest of active phase of labor is defined as failure to progress after ruptured membranes and 4 hours of adequate or 6 hours of inadequate uterine activity
• Arrest of second stage should be at least 2 hours in multiparous and 3 hours in nulliparous | Longer durations may be appropriate with regional anesthesia
• Not all fetal heart rate tracing abnormalities are an indication for cesarean
• Encourage operative delivery procedures when appropriate can help prevent cesarean delivery
• Access to nonmedical interventions and changes in organizational level may reduce cesarean delivery rates

Primary Sources – Learn More: 

First and Second Stage Labor Management

ACOG Practice Bulletin 221: External Cephalic Version

ACOG Practice Bulletin 219: Operative Vaginal Birth

CMQCC: Addendum Toolkit to Support Vaginal Birth and Reduce Primary Cesareans

A Standardized Approach for Category II Fetal Heart Rate with Significant Decelerations: Maternal and Neonatal Outcomes (Shields)

Intrapartum Management of Category II Fetal Heart Rate Tracings: Towards Standardization of Care (Clark)

Related ObG Topics:

Meta-analysis: External Cephalic Version Following Previous Cesarean

External Cephalic Version – 18 Years Experience

Does Persistent Breech Presentation Increase the Risk for External Cephalic Version Failure?

Professional Recommendations: Delivery of Breech Presentation at Term

Obesity in Pregnancy: Classification and Clinical Implications

Macrosomia: Determination of EFW and Recommendations for Delivery

How Well Can Experienced Clinicians Identify Pending Neonatal Encephalopathy Using EFM?

Category II Tracings, Algorithms and Recognition of Metabolic Acidemia

The ARRIVE Trial and Professional Guidance: Elective 39 Week Induction to Reduce the Risk of Cesarean Section