Uterine dehiscence 11s9 (0.7)
Hysterectomy 41 (0.2) 76 (0.5) 1.38 (1s.04-1.85) 0.77 (0.51-1s.17) .03 .22 aDenominator is 15,338 for the trial of labor group and 15,014 for the elective repeat cesarean delivery group.
confidence interval; HIE hypoxic ischemic encephalopathy; NA not applicablesNICHD = National Institute of Child Health and Human Development; NS = not significant.
Adapted from Landon, 2004.
In the systematic review, the absolute risk of transient tachypnea of the newborn was slightly higher with ERCD compared with TOAC-4.2 versus 3.6 percent (Guise, 2010). But, neonatal bag and mask ventilation were used more often in newborns delivered following TOAC than in those delivered by ERCD-5.4 versus 2.5 percent. Finally, there are no signiicant diferences in 5-minute Apgar scores or neonatal intensive care unit admission rates for newborns delivered by TO AC compared with those delivered by ERCD. Birth trauma from lacerations is more commonly seen in neonates born by ERCD.
Few high-quality data are available to guide selection of TO AC candidates. In a population-based cohort study of 41,450 women he type and number of prior cesarean deliveries are overriding factors in recommending TOAC. Women with one prior low-transverse hysterotomy have the lowest risk of symptomatic scar separation (Table 31-3). The highest risks are with prior vertical incisions extending into the fundus, such as that
TABLE 31 -3. Types of Prior Uterine Incisions and Estimated Risks for Uterine Rupture delivering in California hospitals, Gregory and colleagues (2008) Classical reported a TOAC success rate of74 percent when no maternal, T-shaped fetal, or placental complications were present. Several algorithms and nomograms have been developed to aid prediction, but none has demonstrated reasonable prognostic value (Grobman, 2007b, 2008,i2009; Macones, 2006; Metz, 2013; Srinivas, 2007). A predictive model for failed trial of labor, however, was found to be somewhat predictive of uterine rupture or dehiscence (Stanhope, 2013). Despite these limitations for precision, several points are pertinent to candidate evaluation and are described in the next sections. Current recommendations of the American College of Obstetricians and Gynecologists (2017 a) are that most women with one previous low-transverse hysterotomy are candidates, and if appropriate, they should be counseled regarding TOAC and ERCD options. Although not our practice, those with two prior low-transverse incisions may be considered.
aSee text for definition.
Data from the American College of Obstetricians and Gynecologists, 201s7a; Cahill, 20s1 Ob; Chauhan, 2002; Landon, 2006; Macones, 2005a,b; Martin, 1997; Miller, 1994; Sciscione, 2008; Society for Maternal-Fetal Medicine, 2012; Tahseen, 201s0.
FIGURE 31-3 Ruptured vertical cesarean delivery scar (arrow) identified at time of repeat cesarean delivery early in labor. The two black asterisks to the left indicate some sites of densely adhered omentum.
shown in Figure 3i1-3. Importantly, in some women, a classical scar will rupture before labor onset, and this can happen several weeks before term. In a review of 157 women with prior classical cesarean delivery, one woman had a complete uterine rupture before labor onset, whereas 9 percent had a uterine dehiscence (Chauhan, 2002).