Few issues in modern obstetrics have been as controversial as the management of the woman who has had a prior cesarean delivery. For many decades, a scarred uterus was believed by most to contraindicate labor out of fear of uterine rupture. In 1916 Cragin made his famous, oft-quoted, and now seemingly excessive pronouncement, “Once a cesarean, always a cesarean.” Recall that when this statement was made, the classical vertical uterine incision was used almost universally. Even so, some of his contemporaries did not totally agree with his pronouncement. For example, J. Whitridge Williams (1917) termed the statement “an exaggeration” in the fourth edition of Williams Obstetrics.
In the 1920s the technique of low-transverse uterine incision was introduced by Kerr (1921). Leading obstetrical institutions subsequently reported that although catastrophic uterine rupture developed in at least 4 percent of prior classical incisions, only about 0.5 percent of transverse incisions ruptured. And while caution reigned, beginning in the 1950s comfort with the low-transverse incisions resulted in a number of reports that described the de facto policy of a trial of labor in some women without recurring indications for cesarean delivery. And even with repeat cesarean delivery being the stated norm, Hellman and Pritchard (1971) wrote in the 14th edition of Williams Obstetrics that “many reliable institutions, however, report a 30-to 40-percent rate of vaginal deliveries following cesarean section without difficulty.” In 1978, Merrill and Gibbs reported that subsequent vaginal delivery was safely accomplished at the University of Texas at San Antonio in 83 percent of women with a prior cesarean delivery.
Thus, interest was rekindled in vaginal birth especially as the rates of primary cesarean delivery were increasing at an unprecedented pace. Between 1980 and 1988, for example, the cesarean rate jumped from 17 to 25 percent. Meanwhile, more evidence had accrued that uterine rupture was infrequent and rarely catastrophic. In an effort to address the rising cesarean delivery rate, the American College of Obstetricians and Gynecologists (1988) recommended that most women with one previous low-transverse cesarean delivery should be counseled to attempt labor in a subsequent pregnancy. Accordingly, the frequency of vaginal birth after cesarean—commonly referred to as VBAC—increased significantly. And as shown in Figure 26-1, by 1996 almost a third of women with a prior cesarean were being delivered vaginally. Pitkin (1991), who was editor of Obstetrics & Gynecology at that time, wrote that “without question, the most remarkable change in obstetric practice over the last decade was management of the woman with prior cesarean delivery.”
Total and primary cesarean delivery rates and vaginal birth after previous cesarean (VBAC) rate: United States, 1989–2004. aVBAC = number of vaginal births after previous cesarean delivery per 100 births. bPercentage of all live births by cesarean delivery. cNumber of primary cesarean deliveries ...