Clinical Review
UPDATE ON OBSTETRICS
The drive to do more and do it faster continues, leading to notable advances in prenatal diagnosis and fetal therapy, but is not sustainable over...
Over the past year, much attention has been devoted to labor curves. Is the original Friedman labor curve, which dates to the 1950s, still applicable today? Or do contemporary women labor differently? And if we update our approach to labor management, can we reduce the rate of primary cesarean?
In this Update, we explore these questions, as well as two others:
- How do we minimize infectious morbidity in pregnancy?
- How much prenatal screening is too much?
Is adherence to new labor curves the best way to reduce the rate of primary cesarean?
American College of Obstetricians and Gynecologists. Obstetric Care Consensus No. 1: Safe prevention of the primary cesarean delivery. Obstet Gynecol. 2014;123(3):693–711.
Cohen WR, Friedman EA. Perils of the new labor management guidelines [published online ahead of print September 16, 2014]. Am J Obstet Gynecol. doi:10.1016/j.ajog.2014.09.008.
In 2012, the cesarean delivery rate in the United States remained at 32.8%, a high percentage when one considers the increased risks that major abdominal surgery poses in both the short and long term (blood loss, transfusion, infection, venous thromboembolism, abnormal placentation, hysterectomy).1 The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) have made it a priority to reduce the cesarean delivery rate, focusing their efforts on the primary cesarean. In March 2014, they jointly issued guidelines on the “Safe prevention of the primary cesarean delivery,” highlighting labor dystocia as a top cause.
When contemporary data from the Consortium on Safe Labor were applied to the original Friedman labor curve, investigators found that the active phase of labor may be slower than previously thought.2 The maximum slope for the rate of cervical change was not observed until 6 cm of dilation. This finding potentially changes the point at which arrest of the active phase may be declared. The maximum duration of augmentation with oxytocin also has been extended, based on studies that demonstrated increased vaginal delivery rates.
The Consortium on Safe Labor proposed that, by subjecting a contemporary population to decades-old standards, we have been intervening with primary cesarean too early in the treatment of labor dystocia.
What the guidelines say
The new recommendations from ACOG-SMFM suggest that arrest of the active phase of labor can be declared only when the patient is dilated at least 6 cm with ruptured membranes after either 4 hours of adequate uterine contractions or at least 6 hours of oxytocin administration with inadequate uterine contractions or no cervical change.
Although the recommendations state that there is no maximum duration of the second stage of labor, we may increase the vaginal delivery rate by increasing the duration of pushing to 2 hours for a multiparous patient and 3 hours for a nulliparous patient (with an additional hour when an epidural is given).
Are the recommendations ready for prime time?
In response to the recommendations, Cohen and Friedman (author of the original labor curve) published “Perils of the new labor management guidelines,” cited above. In this commentary, they caution against universal acceptance of the guidelines without further validation. They argue that the analytical method used—and not labor itself—has changed, with possible selection biases and unadjusted confounders altering the shape of the dilatation curve. Cohen and Friedman suggest that serial evaluation of the patient is preferable to an arbitrary cutoff of 6 cm.
They also criticize other aspects of the guidelines, focusing on universal use of intrauterine pressure catheters, amniotomy, and a specific duration of pushing without consideration of descent. A “one size fits all” approach may incur risk to both the mother and the fetus without proven benefit, they contend. Clinical judgment and continuous evaluation of the likelihood and safety of vaginal delivery also are encouraged rather than a reliance on labor curves in isolation.
They urge further validation before adoption of the recommendations. “If we direct our clinical and basic science investigations to the goal of practicing obstetrics in a manner that optimizes maternal and newborn outcomes, the ideal cesarean delivery rate, whatever it may be, will follow,” they write.
What this EVIDENCE means for practice
Proceed with caution when applying labor curves to patients. Use clinical judgment in conjunction with any new guidelines.
Be vigilant for infectious threats to your obstetric population
Jamieson DJ, Uyeki TM, Callaghan WM, Meaney-Delman D, Rasmussen SA. What obstetrician-gynecologists should know about Ebola: a perspective from the Centers for Disease Control and Prevention. Obstet Gynecol. 2014;124(5):1005–1010.
American College of Obstetricians and Gynecologists. Committee Opinion No. 614: Management of pregnant women with presumptive exposure to Listeria monocytogenes. Obstet Gynecol. 2014;124(6):1241–1244.
