By John C. Hobbins, MD
Professor, Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Aurora
Dr. Hobbins reports no financial relationships relevant to this field of study.
Our understanding of the conduct of labor has undergone periodic re-evaluation. In the 1950s, cesarean delivery was a major operation. Today, the procedures are shorter, accompanied by less surgical fanfare, and associated with fewer days in the hospital. Nevertheless, as the only other option to vaginal delivery, the operation, performed in 35% of cases for failure to progress, still should be considered “major” considering its potential for maternal complications.
Arrest of Labor in the First Stage
In 1954, Emmanuel Friedman published a study that laid the groundwork for quantifying time limits for normal latent and active phases of labor.1 It was based on data from 500 women whose labors were unaccompanied by epidurals. Only 13% of the women had oxytocin for induction or augmentation. The Friedman curve defined the upper limits of normal for the latent phase (> 20 hours for multiparas and > 46 hours for nulliparas) and for progress in the active phase (< 1.5 cm/hour for multiparas and < 1.2 cm/hour for nulliparas). Arrest of labor in the active phase was defined as no change in cervical dilation for two hours or more in the active stage once 4 cm of dilation was attained.
These data were challenged later because Friedman’s pure cohort might not represent today’s laboring patients. The Consortium for Safe Labor published data from 19 hospitals and 62,000 patients showing that the steepest slope of cervical dilation did not occur until 6 cm and that some patients attaining successful vaginal deliveries could take up to six hours to progress between 4 cm and 5 cm and three hours to progress between 5 cm and 6 cm dilation.2 This caused the Society for Maternal-Fetal Medicine to suggest the following contemporary guidelines:3
- A prolonged latent phase should not be reason alone for cesarean delivery since amniotomy and/or oxytocin augmentation should move most patients into the active phase.
- Active phase arrest should not be diagnosed before 6 cm.
- Cesarean delivery is not advised unless no progress in cervical dilation has been made for four hours of documented adequate contractions post-amniotomy or after more than six hours of adequate oxytocin-assisted contractions.
Arrest of Labor in the Second Stage
For years, failure of descent represented a patient’s inability to achieve an increase in fetal head station after two hours of pushing or, in some definitions, to attain delivery. However, published opinions from the Consortium for Safe Labor included a more liberal approach to defining arrest in the second stage as > 2 hours in a multipara and > 3 hours in a nullipara.2 Even more time was allowed for those with epidurals or malpresentations.
In 2016, Wilson-Leedy et al compared 200 patients managed with the new guidelines and 200 patients not managed this way.4 They found the overall cesarean delivery rate decreased from 26.9% to 18.9%, and the cesarean delivery rate in patients with cervices < 6 cm decreased from 7.1% to 1.1% with the newer guidelines.
In addition to achieving vaginal delivery more frequently, are there any greater risks with the new guidelines? Several studies addressed this question, but perhaps the most attention-getting study challenging the newer guidelines was conducted on 7,800 laboring patients.5 Rosenbloom et al compared patients who delivered between 2010 and 2014 and those who delivered after the new guidelines were applied in 2014. The cesarean delivery rate actually rose from 15.8% to 17.3%, and there were 1.6- and 1.8-fold increases in adverse maternal and neonatal outcomes, respectively. However, as with any before-and-after study, some non-guideline practices or factors introduced or deleted during the “after” group’s care could have affected the results.
The problem with any type of rigid guideline that reduces myriad variables into a generic recommendation is that one size does not always fit all. For example, some patients without red flags might need even more than six hours to make progress. Yet others with unfavorable factors might benefit more from the old guidelines rather than prolonging an inevitable surgical conclusion. This has caused some authors to construct computer-generated formulas that consider many favorable or unfavorable factors to predict outcomes for individual patients.6 Various methods can help better attain a vaginal delivery.
Epidural anesthesia: Epidurals may help to shorten labor in some anxious patients, but one study has shown that first-stage labors last an average of 26 minutes longer and second stages last an average of 15 minutes longer.7 Often, first-stage times are increased when epidurals are administered before the active phase is attained.
Amniotomy: This method has been a staple of obstetricians for either improving success of labor induction or augmenting contraction strength if first-stage progress has stalled. In 1995, amniotomy was found to shorten labor but also to increase the rate of amnionitis.8 In a 2008 publication based on a Cochrane database, Neilson found no statistically significant effect on first-stage length, Apgar scores, or cesarean delivery rate.9
Hydration: In some centers, the NPO (nothing by mouth) policy remains for patients in labor. Some data show that intravenous fluids shorten labor in this setting, particularly if the infusion is given at a rate of 250 mL/hour vs. 125 mL/hour).10 However, it is unclear if infusion is any better than liberal ingestion of clear fluids in shortening labor or avoiding cesarean delivery.
Ambulation: These results are mixed. Lawrence et al found a halving of the cesarean delivery rate and the need for operative vaginal delivery when ambulation was encouraged.11
The importance of nursing support: In one often-quoted study, labor nurses were tracked according to the cesarean delivery rates of patients they cared for while on duty.12 Those in the lower quartile had patients with shorter labors (4.4 hours vs. 5.6 hours) and fewer forceps deliveries (13% vs. 26%) than nurses in the highest cesarean delivery quartile. This implies that motivation does make a difference.
Assessment of Fetal Station
Fetal station is an important variable in predicting a successful vaginal delivery or in making the ultimate decision for cesarean delivery for “failure of descent” in the second stage. However, our assessment of station is one of the most subjective endeavors a provider undertakes. The ritual requires the examiner to construct an imaginary line between the two ischial spines and then, with the same finger, to determine how many centimeters the leading part of the fetal skull is below or above this line. No provider’s brain has the three-dimensional capability to determine this precisely, especially when the head is well below the level of the spines. Throw in 2-3 cm of caput and it is impossible to tell if progress is being made in descent of the fetal skull.
In 2009, Barbera et al described an alternative method using ultrasound.13 It entailed applying a standard curvilinear transducer to the vulva (trans-perineal ultrasound) to get a midline sagittal image that incorporates the length of the median raphae of the symphysis pubis and the leading edge of the fetal skull. The “angle of progression” is constructed from two lines directed from the inferior border of the symphysis, one along the long axis of this structure and another to the leading edge of the fetal skull. The quantified angle of progression that is created represents an objective method to assess fetal station. Most importantly, the method can be used serially to determine whether there has been true descent of the head through the pelvis. Following its introduction, many papers have appeared from Europe showing the efficacy of trans-perineal ultrasound in predicting successful vaginal delivery14,15 or operative delivery.16 Interestingly, although the concept arose in the United States, it has not been taken up here where, with our heads in the sand, we continue “winging it” with a wholly subjective method.
Parting Comments
Here are some unsolicited thoughts from someone who has spent the last 50 years going with the flow, but also sometimes bucking it. Protocols, computerized models, and even ultrasound-derived methods can help with managing labor. However, decisions to perform a cesarean delivery also should be based on trends in a patient’s clinical course rather than on one isolated snapshot. The art of medicine involves decisions based on information that the provider has filed while watching the whole story unfold and by employing, on occasion, an approach of “been there, done that” or, alternatively, “been there and wish I had not done that.”
Today, we also frequently depend on evidence-based guidelines and formulas that are designed to protect our patients and us from disastrous missteps. Protocols are particularly important to keep providers on the same page as we enter an era of shift medicine, where “laborists” are replacing primary providers for in-hospital activities.
I get it. Despite the “highs” of participating in one of the most important events in people’s lives, the camaraderie on the labor deck, and the occasional, but addictive, jolts of adrenaline, I gave up labor and delivery coverage when I realized that long shifts, interspersed with regular daytime requirements, were not making me a better decision-maker in either job.
I thought patients would revolt against the laborist concept, but they seem to have accepted it, or maybe they just have become inured to it, along with some patient-unfriendly aspects of our present healthcare system. However, as we move forward, the motto that pregnancy is not an illness, including the part that involves delivery, should not be forgotten. Unless a woman strays off course, there is no need to engage in unnecessary meddling. Most importantly, she should be involved in fashioning her delivery plan and must be properly informed about why any change in that plan is being contemplated. For me, the nurse midwife delivery model, with physicians called only if problems arise, makes sense for low-risk women and, frankly, even in some higher-risk women.
Finally, delivering patients empirically at 39 weeks intuitively seems wrong, despite early evidence that cesarean delivery, as well as rates of some maternal and neonatal complications, is lower.17 What has not been studied is the cost and anxiety created by inducing patients with no obvious risks, often accompanied by methods of cervical ripening, IVs, monitors, reallocation of nursing coverages, etc. Also, while we are in the wake of these new findings, it may be too easy to say, “you should have this,” rather than “you could have this.” This needs further evaluation.
I have loved writing these Alerts and Special Features ever since my good friend, Leon Speroff, asked me to help with them 237 Alerts ago. However, it is now time for me to put my yellow-lined pads and pencils to another use. Yes, I still use them. While not missing the monthly deadlines, I certainly will miss these opportunities to cover new information and to share my thoughts with you. Thanks for listening.
REFERENCES
- Friedman E. The graphic analysis of labor. Am J Obstet Gynecol 1954;68:1568-1575.
- Zhang J, Landy H, Branch W, et al. Contemporary patterns of spontaneous labor with normal neonatal outcomes. Obstet Gynecol 2010;116:1281-1287.
- American College of Obstetricians and Gynecologists; Society for Maternal-Fetal Medicine. Obstetric care consensus no. 1: Safe prevention of the primary cesarean delivery. Obstet Gynecol 2014;123:693-711.
- Wilson-Leedy JG, DiSilvestro AJ, Repke JT, Pauli JM. Reduction in the cesarean delivery rate after obstetric care consensus guideline implementation. Obstet Gynecol 2016;128:145-152.
- Rosenbloom JI, Stout M, Tuuli MG, et al. New labor management guidelines and changes in cesarean delivery patterns. Am J Obstet Gynecol 2017;689:e1-8.
- Hamilton EF, Warrick PA, Collins K, et al. Assessing first-stage labor progression and its relationship to complications. Am J Obstet Gynecol 2016;214:358.e1-8.
- Leighton BL, Halpern SH. The effects of epidural analgesia on labor, maternal, and neonatal outcomes: A systematic review. Am J Obstet Gynecol 2002;186(5 Suppl Nature):S69-S77.
- Mercer BM, McNanley T, O’Brien JM, et al. Early versus late amniotomy for labor induction: A randomized trial. Obstet Gynecol 1995;173:1321-1325.
- Neilson JP. Amniotomy for shortening spontaneous labour. Obstet Gynecol 2008;111:204-205.
- Dawood F, Dowswell T, Quenby S. Intravenous fluids for reducing the duration of labour in low risk nulliparous women. Cochrane Database Syst Rev 2013;18:CDOO7715.
- Lawrence A, Lewis L, Hofmeyr GJ, et al. Maternal positions and mobility during first stage of labour. Cochrane Database Syst Rev 2009;2:003934.
- Radin TG, Harmon JS, Hanson DA. Nurses’ care during labor: Its effect on the cesarean birth rate of healthy, nulliparous women. Birth 1993;20:14-21.
- Barbera AF, Pombar X, Perugino G, et al. A new method to assess fetal head descent in labor with transperineal ultrasound. Ultrasound Obstet Gynecol 2009;33:313-319.
- Ghi T, Maroni E, Youseff A, et al. Sonographic pattern of fetal head descent: Relationship with duration of active second stage of labor and occiput position at delivery. Ultrasound Obstet Gynecol 2014;44:82-89.
- Torkildsen EA, Salvesen KA, Eggebo TM, et al. Prediction of delivery mode with transperineal ultrasound in women with prolonged first stage of labor. Ultrasound Obstet Gynecol 2011;37:702-708.
- Bultez T, Quibel T, Bouhanna P, et al. Angle of fetal head progression measured using transperineal ultrasound as a predictive factor for vaginal extraction failure. Ultrasound Obstet Gynecol 2016;48:86-91.
- Grobman WA, Rice MM, Reddy UM, et al. Labor induction versus expectant management in low-risk nulliparous women. N Engl J Med 2018;379:513-523.
