According to the workshop, these definitions “vary somewhat from published criteria and are recommended in recognition of more recent findings regarding labor progress that challenge our long-held practices based on the Friedman curve.” Shown in Table 23-3 is a synopsis of some of these workshop recommendations for revised labor management criteria. The adequate time for each of these stages appears to be longer than traditionally estimated.” The implication of this viewpoint is that changing the diagnostic criteria of abnormal labor will reduce the excessive cesarean birth rate. Specifically, it concluded that “adequate time for normal latent and active phases of the first stage and for the second stage should be allowed as long as the maternal and fetal conditions permit. The workshop recommended new definitions for arrest of labor progress to prevent unnecessary first cesarean deliveries. To address this increasing cesarean delivery rate, a workshop was convened by the National Institute of Child Health and Human Development (NICHD) and the American College of Obstetricians and Gynecologists (Spong, 2012). Given that many repeat cesarean deliveries are performed after primary operations for dystocia, it is estimated that 60 percent of all cesarean deliveries in the United States are ultimately attributable to the diagnosis of abnormal labor (American College of Obstetricians and Gynecologists, 2013). The 2010 rate of 32.8 percent could suggest that this long trend of increasing cesarean rates may now be moderating (Martin, 2012). This was the 13th consecutive year in which the cesarean rate increased, and it represented a nearly 60-percent increase compared with 20.7 percent in 1996. In 2009, the total cesarean delivery rate for all births in the United States reached a record high of 32.9 percent (Martin, 2011). In the absence of objective means of precisely distinguishing these two causes of labor failure, clinicians must rely on a trial of labor to determine if labor can be successful in effecting vaginal delivery. Indeed, according to the American College of Obstetricians and Gynecologists (2013), the bony pelvis rarely limits vaginal delivery. Although artificial separation of labor abnormalities into pure uterine dysfunction and fetopelvic disproportion simplifies classification, it is an incomplete characterization because these two abnormalities are so closely interlinked. Thus, ineffective labor is generally accepted as a possible warning sign of fetopelvic disproportion. Uterine muscle malfunction can result from uterine overdistention or obstructed labor or both. Because of this, abnormalities in fetopelvic proportions become more apparent once the second stage is reached. (Adapted from Williams, 1903.)Īs also shown in Figure 23-1B, after complete cervical dilatation, the mechanical relationship between the fetal head size and position and the pelvic capacity, namely fetopelvic proportion, becomes clearer as the fetus descends. During the second-stage of labor, showing formation of the birth canal. Terms presented in Table 23-2 and their diagnostic criteria more precisely describe abnormal labor.įIGURE 23-1 Diagrams of the birth canal. Neither of these two expressions is specific. This term reflects lack of progressive cervical dilatation or lack of fetal descent. A second phrase, failure to progress in either spontaneous or stimulated labor, has become an increasingly popular description of ineffectual labor. True disproportion is a tenuous diagnosis because two thirds or more of women undergoing cesarean delivery for this reason subsequently deliver even larger newborns vaginally. Such absolute disproportion is now rare, and most cases result from malposition of the fetal head within the pelvis (asynclitism) or from ineffective uterine contractions. But the term originated at a time when the main indication for cesarean delivery was overt pelvic contracture due to rickets (Olah, 1994). Of these, cephalopelvic disproportion is a term that came into use before the 20th century to describe obstructed labor resulting from disparity between the fetal head size and maternal pelvis. Commonly used expressions today such as cephalopelvic disproportion and failure to progress are used to describe ineffective labors. Abnormalities that are shown in Table 23-1 often interact in concert to produce dysfunctional labor.
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