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.

SYNOPSIS: A recent study involving patients being induced after two previous cesarean sections showed that they had similar rates of success, with equally low rates of neonatal and maternal morbidity, as those having induction after one previous cesarean section and even those who had outright repeat cesarean sections.

SOURCE: Miller ES, Grobman WA. Obstetric outcomes associated with induction of labor after two prior cesarean deliveries. Am J Obstet Gynecol 2015;213:89.e1-5.

The July issue of the American Journal of Obstetrics and Gynecology was loaded. Although I discussed three articles in that issue last month (on the cerebroplacental ratio), I have revisited it again to focus on an important study involving patients who had trials of labor after previous cesarean sections (TOLAC).

After a time when providers were reluctant to induce patients with previous cesarean sections, there was a more permissive approach to inductions pursuant to the American College of Obstetricians and Gynecologists’ loosened stance on this. Miller et al addressed the question, “If induction may be appropriate for patients with one previous cesarean section, what are the chances of success for those with two previous cesarean sections?”1 Data between 1999 and 2002 from 19 academic centers were reviewed and three groups were identified: 1) patients induced after one previous cesarean section, 2) patients induced with two previous cesarean sections, and 3) patients electing to have a repeat cesarean section.

There were 10,262 patients with previous cesarean sections in the analysis. Of these, 4252 patients had inductions and 152 (3.6%) of the inductions were in patients who had had two prior sections. In the whole group, 6010 (58.6%) had outright repeat cesarean sections. In those with one previous section, 2840 (69.3%) had successful vaginal births after cesarean sections (VBACs) while 99 (65.1%) were successful after two cesareans. Individual and composite maternal morbidities were no different between all three groups, indicating that inducing patients with one or two sections was no more risky for the mother than having an outright repeat cesarean section. Last, there were no significant differences between groups in neonatal morbidities (low Apgar scores, hypoxemia and ischemic encephalopathy, or perinatal mortality). Even after accounting for confounders, the overall chances of having a successful VBAC were no different among single and double cesarean patients.

COMMENTARY

In 2013, 1,284,000 deliveries were accomplished by cesarean section, accounting for a cesarean section rate of 32.7%.2 Although this rate has actually dropped slightly, very few would say that it is just about right. As chronicled in an OB/GYN Clinical Alert commentary in 2010,3 the rate of VBAC in 1990 was 19.9%, at a time when the cesarean section rate was only 22.7%. Interestingly, that figure was thought to be too high and there was an increased thrust to drop the cesarean section rate even further by hyping the option of VBAC. And it worked, with the rate of VBACs rising over the next 6 years to 28.3%. Then, as stated in an article in 2010,4 because of “concern about patient safety and physician liability,” the availability of trial of labor after cesarean section dropped down to 8.5% (2013).

Cesarean sections beget repeat cesarean sections which, in turn, beget triple operations, etc. The article from Miller et al indicates that even when patients are induced after two cesarean sections, the maternal risks and neonatal morbidities were no different than in those patients induced with one scar or, most importantly, who had outright repeat cesarean sections.1 And two out of three patients in the study had successful VBACs under these circumstances.

The following information can be useful in counseling patients considering trial of labor after cesarean section:

  1. The success rate in general is 74%, rising to 83% when a previous vaginal delivery had been accomplished.5
  2. The risk of uterine rupture is about 0.47%,5 but is lower in ideal candidates (a uterine scar thickness of > 2.2 mm before delivery, a birth to birth interval of > 18 months, and a two-layer closure at the time of the last section).6

The rewards of VBAC include: avoiding a (still) major operation with potential maternal morbidity, quicker recovery, fewer days in the hospital, a more natural experience for many, and a decrease in cost to everyone (about $7.8 billion a year is spent on cesarean sections in the United States). This study shows that even induction seems safe and, interestingly, another article in the same issue7 indicates TOLAC to be as safe in those with cesarean scars of “unknown location” as those with known previous low transverse incisions. For years, this had been a deterrent to offering this option.

So it seems that in the right hospital setting we should now be going back to “encouraging” appropriate candidates to have the TOLACs rather than just “offering” this option, and articles such as this should chip away at the fear of litigation that was at least partially responsible for the downward trend in VBACs.

REFERENCES

  1. Miller ES, Grobman WA. Obstetric outcomes associated with induction of labor after two prior cesarean deliveries. Am J Obstet Gynecol 2015;213:89.e1-5.
  2. Hamilton BE, et al. Births: Preliminary Data for 2013. National Vital Statistics Report 2014;63:1-15.
  3. Hobbins J. New insights into VBACs and maternal and neonatal outcomes. OB/GYN Clinical Alert 2010;27:33-35.
  4. Gregory KD, et al. Trends and patterns of vaginal birth after cesarean availability in the United States. Semin Perinatol 2010;34:237-243.
  5. Guise JM, et al. Vaginal birth after cesarean: New insights on maternal and neonatal outcomes. Obstet Gynecol 2010;115:1267-1278.
  6. Bujold E, et al. Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment. Am J Obstet Gynecol 2009;201:320.e1-6.
  7. Smith D, et al. Risk of uterine rupture among women attempting vaginal birth after cesarean with unknown uterine scar. Am J Obstet Gynecol 2015;213:80.e1-5.