Trial of labor after cesarean delivery with a lower-segment, vertical uterine incision: is it safe?

Trial of labor after cesarean, vaginal birth after cesarean, and the risk of uterine rupture: an expert review

The decision to pursue a trial of labor after cesarean delivery is complex and depends on patient preference, the likelihood of successful vaginal birth after cesarean delivery, assessment of the risks vs benefits of trial of labor after cesarean delivery, and available resources to support safe trial of labor after cesarean delivery at the planned birthing center. The most feared complication of trial of labor after cesarean delivery is uterine rupture, which can have catastrophic consequences, including substantial maternal and perinatal morbidity and mortality. Although the absolute risk of uterine rupture is low, several clinical, historical, obstetrical, and intrapartum factors have been associated with increased risk. It is therefore critical for clinicians managing patients during trial of labor after cesarean delivery to be aware of these risk factors to appropriately select candidates for trial of labor after cesarean delivery and maximize the safety and benefits while minimizing the risks. Caution is advised when considering labor augmentation and induction in patients with a previous cesarean delivery. With established hospital safety protocols that dictate close maternal and fetal monitoring, avoidance of prostaglandins, and careful titration of oxytocin infusion when induction agents are needed, spontaneous and induced trial of labor after cesarean delivery are safe and should be offered to most patients with 1 previous low transverse, low vertical, or unknown uterine incision after appropriate evaluation, counseling, planning, and shared decision-making. Future research should focus on clarifying true risk factors and identifying the optimal approach to intrapartum and induction management, tools for antenatal prediction, and strategies for prevention of uterine rupture during trial of labor after cesarean delivery. A better understanding will facilitate patient counseling, support efforts to improve trial of labor after cesarean delivery and vaginal birth after cesarean delivery rates, and reduce the morbidity and mortality associated with uterine rupture during trial of labor after cesarean delivery.

Labor characteristics and intrapartum interventions in women with vaginal birth after cesarean section

Background

With the development of China’s two-child-policy, vaginal birth after cesarean section (VBAC) has aroused public concern. It is important to understand the labour characteristics and intrapartum management of women attempting VBAC to enhance the rates of successful VBAC. The purpose of our research was to investigate the differences in the characteristics of labor, intervention measures and perinatal outcomes between women who had a VBAC and primiparas or multiparas not undergoing VBAC, providing clinical references of intrapartum management for women who are planning a VBAC.

Material and methods

This observational retrospective study enrolled all women who laboured spontaneously and who had a VBAC (n = 139) at the Second Affiliated Hospital of Wenzhou Medical University in China between 2016 and 2019. They were allocated into VBAC group A (the previous cesarean section was performed before dilation of the cervix) and VBAC group B (the previous cesarean section was performed after dilation of the cervix). The primipara control group included 149 primiparae, and the multipara control group included 155 multiparae with second vaginal birth. Durations of labor, intervention measures and perinatal outcomes were compared among the groups.

Results

The durations of labor, intrapartum interventions and maternal and neonatal outcomes in VBAC group A were similar to those of the VBAC group B. However, all women who had a VBAC and those in VBAC group A had shorter first, second and the total stages of labor than primiparae. All women with VBAC and those in VBAC group B had longer second stage of labor, but shorter third stage of labor than multiparae. Oxytocin, labor analgesia and artificial rupture of membranes were administered less often in women with VBAC than in primiparae, while phloroglucinol was administered more often in women with VBAC than in multiparae. Women who had a VBAC were more likely to receive episiotomy and had higher incidences of postpartum hemorrhage than primipara and multipara women.

Conclusions

Labor characteristics, intrapartum interventions and perinatal outcomes in women who had a VBAC with cervical dilation were similar to those in women who had a VBAC without cervical dilation before the previous cesarean section, but differed significantly from those of multiparae and primiparae who did not undergo VBAC.

Induction of Labour. Guideline of the DGGG, OEGGG and SGGG (S2k, AWMF Registry No. 015-088, December 2020)

Aim The aim of this official guideline published and coordinated by the German Society of Gynaecology and Obstetrics (DGGG) in cooperation with the Austrian Society of Gynaecology and Obstetrics (OEGGG) and the Swiss Society of Gynaecology and Obstetrics (SGGG) is to provide a consensus-based overview of the indications, methods and general management of induction of labour by evaluating the relevant literature. Methods This S2k guideline was developed using a structured consensus process which included representative members from various professions; the guideline was commissioned by the guidelines commission of the DGGG, OEGGG and SGGG. Recommendations The guideline provides recommendations on the indications, management, methods, monitoring and special situations occurring in the context of inducing labour.

Safety and feasibility of trial of vaginal labor after cesarean section: A retrospective study

By observing and analyzing the success rate of Tai'an City central hospital TOLAC and VBNC and various indicators after delivery, we make sure whether TOLAC is safe and feasible to be promoted in Tai'an area.Between January and December 2017, data of 144 cases undergoing TOLAC, 152 cases undergoing VBNC, 152 cases undergoing RCS and 142 case undergoing PCS in Tai'an City Central Hospital were retrospectively analyzed. The success rate of vaginal delivery, labor time, 24 hours postpartum hemorrhage, hospital stay, Apgar score of newborns and puerperal morbidity were observed.Primary study outcomes: The success rates of the TOLAC and VBNC groups were 93.06% and 93.42%, respectively, where the difference was not statistically significant (P = .901). Secondary study outcomes: There were no significant differences in labor time (P = .0249), amount of 24 hours postpartum hemorrhage (P = .206), Apgar score of newborns (P = .582), hospital stay (P = .194) and puerperal morbidity (P = .942) between the VBAC group and VBNC group. There were statistically significant differences in amount of 24 hours postpartum hemorrhage (P < .001), hospital stay (P < .001) and puerperal morbidity (P = .018), but no difference in Apgar score of newborns (P = .228) between the VBAC group and RCS group. There were significant differences in operation time (P = .011), amount of 24 hours hemorrhage (P = .001), hospital stay (P = .001) and puerperal morbidity (P = .041), but no significant difference in Apgar score of newborns (P = .300) between the RCS and PCS groups.The TOLAC is as safe and feasible as VBNC, and more favorable to the safety of mother and fetus than RCS in Tai'an area.

ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery

Trial of labor after cesarean delivery (TOLAC) refers to a planned attempt to deliver vaginally by a woman who has had a previous cesarean delivery, regardless of the outcome. This method provides women who desire a vaginal delivery the possibility of achieving that goal-a vaginal birth after cesarean delivery (VBAC). In addition to fulfilling a patient's preference for vaginal delivery, at an individual level, VBAC is associated with decreased maternal morbidity and a decreased risk of complications in future pregnancies as well as a decrease in the overall cesarean delivery rate at the population level (). However, although TOLAC is appropriate for many women, several factors increase the likelihood of a failed trial of labor, which in turn is associated with increased maternal and perinatal morbidity when compared with a successful trial of labor (ie, VBAC) and elective repeat cesarean delivery (). Therefore, assessing the likelihood of VBAC as well as the individual risks is important when determining who is an appropriate candidate for TOLAC. Thus, the purpose of this document is to review the risks and benefits of TOLAC in various clinical situations and to provide practical guidelines for counseling and management of patients who will attempt to give birth vaginally after a previous cesarean delivery.

Practice Bulletin No. 184: Vaginal Birth After Cesarean Delivery

Trial of labor after cesarean delivery (TOLAC) refers to a planned attempt to deliver vaginally by a woman who has had a previous cesarean delivery, regardless of the outcome. This method provides women who desire a vaginal delivery the possibility of achieving that goal-a vaginal birth after cesarean delivery (VBAC). In addition to fulfilling a patient's preference for vaginal delivery, at an individual level, VBAC is associated with decreased maternal morbidity and a decreased risk of complications in future pregnancies as well as a decrease in the overall cesarean delivery rate at the population level (1-3). However, although TOLAC is appropriate for many women, several factors increase the likelihood of a failed trial of labor, which in turn is associated with increased maternal and perinatal morbidity when compared with a successful trial of labor (ie, VBAC) and elective repeat cesarean delivery (4-6). Therefore, assessing the likelihood of VBAC as well as the individual risks is important when determining who is an appropriate candidate for TOLAC. Thus, the purpose of this document is to review the risks and benefits of TOLAC in various clinical situations and to provide practical guidelines for counseling and management of patients who will attempt to give birth vaginally after a previous cesarean delivery.

Vaginal birth after cesarean and trial of labor after cesarean: what should we be recommending relative to maternal risk:benefit?

Trial of labor after cesarean (TOLAC) delivery is currently a hot obstetrical topic owing to the acute rise in the rate of cesarean deliveries, both primary and repeat. When the physician and patient are considering TOLAC, several factors should be considered: risk of uterine rupture, contraindications, minimizing risk and morbidity, choosing the appropriate candidate and whether or not to induce. Each patient has her own set of individual risk factors that may decrease her chance of successful vaginal birth after cesarean delivery or increase her risks with TOLAC. Once all things are considered, the risk:benefit of TOLAC should be weighed up before a decision is reached. Each of these factors is discussed in respect to maternal risk:benefit, with the focus on evidence presented in the current literature.

Evaluating trial of scar in patients with a history of caesarean section

Aims:

To analyze the outcome of trial of scar in patients with previous caesarean section and to assess the fetal and maternal complications after trial of scar.

Patients and Methods:

The study was conducted at Military Hospital, Rawalpindi, Pakistan, with 375 pregnant patients who had a previous delivery by caesarean and who had regular antenatal checkup. Data were recorded on special pro-forms designed for the purpose.

Results:

The results from the 375 patients who had one previous lower segment caesarean section due to non-recurrent causes were analyzed and compared with national and international studies. Indications of previous caesarean section (non-recurrent causes) included malpresentations, fetal distress/cord prolapse, failure to progress, severe pregnancy-induced hypertension/eclampsia and twins with abnormal lie of the first twin. 0 218 patients reported spontaneous labor. Among these patients, 176 delivered vaginally and 42 patients had repeat caesarean sections. There were a total of 157 patients who experienced induction of labor. 97 patients were induced by cervical ripening with mechanical method, followed by artificial rupture of membranes and augmentation (if required) with syntocinon infusion. 60 patients were induced with prostaglandin E₂ vaginal tablet.

Conclusion:

This study concludes that females with a prior caesarean are at increased risk for subsequent caesareans, regardless of mode of delivery. Eliminating vaginal-birth-after-caesarean will not eliminate the risk. Therefore, vaginal birth after caesarean should be encouraged in selected cases from obstetric units to reduce the risks of repeated caesarean sections. Failed vaginal-birth-after-caesarean can result in increased morbidity than that with elective caesarean section.

Simultaneous uterine and urinary bladder rupture in an otherwise successful vaginal birth after cesarean delivery

Uterine rupture is the primary concern when a patient chooses a trial of labor after a cesarean section. Bladder rupture accompanied by uterine rupture should be taken into consideration if gross hematuria occurs. We report the case of a patient with uterine rupture during a trial of labor after cesarean delivery. She had a normal course of labor and no classic signs of uterine rupture. However, gross hematuria was noted after repair of the episiotomy. The patient began to complain of progressive abdominal pain, gross hematuria and oliguria. Cystoscopy revealed a direct communication between the bladder and the uterus. When opening the bladder peritoneum, rupture sites over the anterior uterus and posterior wall of the bladder were noted. Following primary repair of both wounds, a Foley catheter was left in place for 12 days. The patient had achieved a full recovery by the 2-year follow-up examination. Bladder injury and uterine rupture can occur at any time during labor. Gross hematuria immediately after delivery is the most common presentation. Cystoscopy is a good tool to identify the severity of bladder injury.

Effect of gestational age at the prior cesarean delivery on maternal morbidity in subsequent VBAC attempt

OBJECTIVE

The purpose of this study was to estimate the effect of gestational age at the time of prior cesarean on maternal morbidity in women attempting vaginal birth after cesarean delivery (VBAC).

STUDY DESIGN

A retrospective cohort study of women attempting VBAC, comparing women with a prior cesarean delivery < or = 34 completed weeks to women with a prior cesarean delivery > 34 weeks. The primary outcome was maternal morbidity, including uterine rupture. Univariable, stratified, and multivariable analyses were used to estimate the effect of a prior cesarean performed at < or = 34 weeks on maternal morbidities.

RESULTS

Of 19,474 women with 1 prior cesarean, 12,535 attempted VBAC and 508 of those had a previous cesarean < or = 34 weeks. Study groups had similar risks of uterine rupture (adjusted OR [AOR], 1.5; 95% CI, 0.7-3.5; P = .32) and composite morbidity (AOR, 0.9; 95% CI, 0.5-1.8; P = .81).

CONCLUSION

Prior cesarean delivery at < or = 34 weeks' gestation does not appear to increase the risk of maternal morbidity in a subsequent VBAC attempt.

The clinical content of preconception care: reproductive history

A history of previous birth of a low birthweight infant, previous cesarean sections, multiple previous spontaneous abortions, prior stillbirth, or uterine anomaly identifies women at increased risk for recurrent abortion, preterm birth, or stillbirth. We review the evidence for the potential benefit of reproductive history in identifying strategies for evaluation and treatment to prevent recurrent adverse pregnancy outcome. We offer evidence-based recommendations for management of women with these histories.

Vaginal birth after cesarean delivery

By 2004, only 9.2% of women in the United States with prior cesareans underwent a term of labor (TOL), although nearly two thirds of these women are actually candidates for a TOL. In this article, the author notes that the principal risk associated with vaginal birth after cesarean delivery (VBAC)-TOL is uterine rupture, which can lead to perinatal death, fetal hypoxic brain injury, and hysterectomy. Risk factors for uterine rupture include number of prior cesareans, prior vaginal delivery, interdelivery interval, and uterine closure technique. The author concludes by noting that a pregnant woman with prior cesarean delivery is at risk for maternal and perinatal complications, whether undergoing TOL or choosing elective repeat operation. Complications of both procedures should be discussed and an attempt made to individualize the risk for uterine rupture and the likelihood of successful VBAC.

Essai de travail en cas de césarienne antérieure

OBJECTIVE

The aim of this review was to relate the evolution of obstetrical management of delivery in women who had previously undergone cesarean delivery and to search the studies supporting the choice of the mode of delivery.

MATERIAL AND METHOD

We identified relevant studies through a computer search in the Medline database.

RESULTS

After a period from 1980 to 2000 when the vaginal delivery had been increasingly recommended, a growth in the use of the planned cesarean delivery was observed. Recent studies report more evidence that uterine rupture is the result of trial of labor and that adverse perinatal outcomes are associated with uterine rupture. The risk of uterine rupture is increased with labor induction. The use of prostaglandins appears to be implicated in a significant increase of uterine rupture, and subsequently might be contraindicated in this situation. The use of oxytocin induced labor appears to increase the risk of uterine rupture. However, the level of adverse perinatal outcomes is low. The choice of the mode of delivery should take into account the likelihood of a further pregnancy, due to the increased risk of placental pathologic conditions depending on the number of repeated cesarean sections.

CONCLUSION

An optimal decision for the mode of delivery should be shared with the pregnant women and all these factors should be taken into consideration.

Evidence-based vaginal birth after Caesarean section

Caesarean section rates are rising globally. Whether vaginal birth after Caesarean (VBAC) is safe and under what circumstances is increasingly important. This chapter reviews the literature about the risks of VBAC, patient and management factors that may alter risk, and discusses ongoing research as well as suggestions for improving future research.

Maternal and perinatal complications with uterine rupture in 142,075 patients who attempted vaginal birth after cesarean delivery: A review of the literature

OBJECTIVE

The purpose of this study was to determine the rate of uterine rupture and its complications as the result of trial of labor after previous cesarean delivery.

STUDY DESIGN

PubMed was searched from 1989 to 2001, with the terms "VBAC, uterine rupture," "trial of labor, uterine rupture," "cesarean delivery, uterine rupture," and "scarred uterus, rupture." For inclusion, reports had to contain data from at least 100 patients with trials of labor that included a description of adverse outcomes. Duplicate reporting from a single institution was excluded. Odds ratios and 95% CIs were calculated.

RESULTS

Seventy-two of the 361 articles (20%) that were identified met the inclusion criteria. A 6.2 per 1000 trial of labor rate of uterine rupture (total=880 uterine ruptures in 142,075 trials of labor) was determined. For every 1000 trials of labor the uterine rupture-related complication rate was 1.8 for packed red blood cell transfusion, 1.5 for pathologic fetal acidosis (cord pH<7.00), 0.9 for hysterectomy, 0.8 for genitourinary injury, 0.4 for perinatal death, and 0.02 for maternal death. The perinatal mortality rate was significantly lower among studies from the United States versus other countries (0.3 vs 0.6; odds ratio, 0.50; 95% CI, 0.26-0.94) and in series that exceeded 1000 patients (0.2 vs 1.7; odds ratio, 7.34; 95% CI, 3.94-13.69).

CONCLUSION

Although relatively uncommon, uterine rupture is associated with several adverse outcomes, depending on the time of the publication and the site and size of the population that was studied.

Uterine rupture during VBAC trial of labor: risk factors and fetal response

For the woman with a prior uterine scar, neither repeat elective cesarean birth nor vaginal birth after cesarean birth (VBAC) trial of labor (TOL) is risk-free. When VBAC-TOL is successful, it is associated with less morbidity than repeat cesarean birth. However, when VBAC-TOL fails due to uterine rupture, severe consequences often ensue. The challenge for clinicians today is to provide women who desire TOL after cesarean birth, a more individualized risk assessment of uterine rupture, thereby enhancing success and optimizing outcome. This article examines major risk factors for uterine rupture during VBAC-TOL. In addition, fetal response to uterine rupture and neonatal outcomes are reviewed.

Vaginal birth after cesarean section versus elective repeat cesarean delivery: Weight-based outcomes

OBJECTIVE

The study was undertaken to compare infectious morbidity and trial of labor (TOL) success stratified by weight in women.

STUDY DESIGN

Vaginal birth after cesarean section (VBAC) candidates were divided into groups based on prepregnancy weight: group I, 70 (<200 pounds); group II, 70 (200-300 pounds); and group III, 69 (>300 pounds).

RESULTS

The TOL success rate was 81.8% in group I compared with 57.1% in group II and 13.3% in group III (P =.001). The overall infectious morbidity was significantly greater in the obese women 39% (P =.001) compared with the average women at 11.4% and the lean women at 5.7%.

CONCLUSION

Infectious morbidity is increased and VBAC success is reduced in patients who weigh more than 300 pounds.

VBAC--is it worth the risk?

Enthusiasm for vaginal birth after cesarean section has waned. As a result, the cesarean birth rate is again on the rise. As a medical community and society we must decide whether the most appropriate question is "What is safest for my baby?" or "Is the risk associated with vaginal birth after cesarean acceptable?" There are risks associated with vaginal birth after cesarean, but in a hospital setting with appropriate resources these risks are low and would still seem to be acceptable.

Vaginal birth after cesarean birth: a national survey of U.S. midwifery practice

Midwives have been providing care for women choosing vaginal birth after cesarean birth (VBAC) for over 20 years. The 1999 American College of Obstetrician Gynecologist (ACOG) guidelines and recent studies questioning the relative safety of VBAC have raised concerns about continuing to offer this option. As part of an effort to understand VBAC care provided by midwives, this study used a national survey sample to examine practices, scope, and recent changes in the provision of VBAC care. The survey, which included demographic and practice items was mailed in late 2000 to a purposeful sample of 325 midwifery practices. The return rate was 62%. Nearly all (94%) of the responding practices were providing VBAC care, and almost half of them (43%) stated that their ability to do so had changed within the past 2 years secondary to recent studies in the obstetric literature, the 1999 ACOG statement, and concerns from third-party payers. Criteria for offering VBAC are stricter, and consent forms are more extensive. Other changes included the need for additional or more intensive support services, in-house anesthesia, and surgery backup. Midwives continue to provide VBAC care, although with some increased restrictions. This study provides background for future research that will determine how midwifery care affects the rate of successful VBACs.

Risk factors for uterine rupture during a trial of labor after cesarean

The rate of vaginal birth among women with a previous cesarean increased from 18.9% in 1989 to 28.3% in 1996. By 1998, the rate had decreased to 26.3% and preliminary data from 1999 suggest that the rate for that year would be even lower (23.4%). It is not known whether that decrease represents a trend related to increasing concern by providers and women about the risk of uterine rupture. Whereas the overall risk of rupture is 1%, our review demonstrates that there is considerable variation of that risk. More than one previous scar, induction of labor, a short interdelivery interval, or a history of postpartum fever during a previous cesarean may increase the risk of a uterine rupture during a trial of labor. However, there does not appear to be an increase in risk associated with low-vertical scars, and a previous vaginal delivery may be somewhat protective. Further delineation of the factors that increase the risk of uterine rupture will permit better prediction of individualized risk and identification of women for whom attempting a vaginal delivery after cesarean represents a safe option.

Techniques for performing caesarean section

In many countries caesarean section has become the mode of delivery in over a quarter of all births. Safety of the mother and cost are the two main areas of concern. Various studies on the techniques of performing a caesarean section have focused on reducing the operating time, blood loss, wound infection and cost. Given the fact that caesarean section is the most commonly performed operation in obstetrics, it is important that trainers and trainees are familiar with the basic surgical techniques and that best practice is followed. At the same time surgeons should take necessary precautions to reduce their risk of exposure to Hepatitis B and HIV. The skin incision and entry into abdominal cavity is best achieved by the modified Cohen's incision. The lower segment transverse uterine incision has stood the test of time over a period of 75 years and remains the best way to enter the uterus. Closure of the uterus in single layer appears to be acceptable, whenever technically possible. Placental delivery should be by controlled cord traction after spontaneous expulsion. Closure of the visceral and parietal layers of the peritoneum no longer seems to be necessary. Obliteration of space in the subcutaneous layer, either by suture or by suction, seems to reduce wound disruption. These issues are being considered in the CAESAR randomized controlled trial of surgical techniques currently underway in England.Prophylactic antibiotics are mandatory in preventing post-operative morbidity. Many of the above mentioned steps have been tested in randomized trials. Further studies are needed to examine a wide range of questions arising from this review, e.g. best position of the patient, the value of exteriorization of the uterus whilst repairing the uterus, and the use of agents to relax the uterus in difficult deliveries.

Vaginal birth after cesarean

Vaginal birth or trial of labor after previous cesarean delivery represents one of the most significant changes in obstetric practice. There are numerous reasons that influence the decision to proceed with either a trial of labor after previous cesarean delivery or elective repeat cesarean delivery. For the majority of women with a previous cesarean delivery, a trial of labor should be encouraged. There are few absolute contraindications. Women with a previous classical uterine incision should not undergo a trial of labor and should be delivered once fetal lung maturity is documented. An attempted trial of labor should not be discouraged in women with a previous low vertical uterine incision, although the patient should be counseled that the evidence as to the risks and benefits of a trial of labor is limited. In those situations where the previous uterine incision is unknown, but suggestive of a classical uterine incision, an argument can be made for elective repeat cesarean delivery once fetal lung maturity is documented. When the history of a uterine incision is unknown and unlikely to be classical, a trial of labor can be attempted after counseling. Close intrapartum management is warranted in this situation. The optimal management of labor in women with a previous low transverse uterine incision who desire a trial of labor with a breech presentation, multiple gestation, orin whom induction of labor is necessary is uncertain; the evidence as to the risks and benefits of a trial of labor is limited and obstetric management should be individualized after counseling. Uterine rupture represents the most catastrophic complication of a trial of labor after previous cesarean delivery. In women suspected of having a uterine scar injury, prompt intervention is necessary to minimize both maternal and neonatal complications. Women who are not successful with a trial of labor require repeat cesarean delivery and appear to be at greatest risk for maternal complications. Identifying those women most likely to be successful with an attempted trial of labor after previous cesarean while also incurring the least maternal and perinatal morbidity and mortality would be ideal. At present, however, there is no sufficiently predictive method to identify those women most likely to benefit from an elective repeat cesarean delivery. The management of labor in women with a previous uterine scar is not low risk. As the number of women who attempt vaginal birth after previous cesarean delivery increases, we should focus on trying to develop reliable methods of identifying women who should and should not undertake a trial of labor after cesarean delivery.

The case for trial of labor in the patient with a prior low-segment vertical cesarean incision

OBJECTIVE

Our purpose was to review recent obstetric literature detailing the subsequent delivery experience of patients with a prior low-segment vertical cesarean incision and to derive recommendations for practice on the basis of this information.

STUDY DESIGN

Ten studies that included information about pregnancy outcome in patients with prior low-segment vertical cesarean operations were retrieved and reviewed from the American obstetric literature since 1981 and from a review of all abstracts presented annually since 1981 to the Society of Perinatal Obstetricians.

RESULTS

Altogether, information about subsequent pregnancy outcome for 382 patients with prior low-segment vertical cesarean delivery was available for analysis. Among the 372 patients with complete patient population information, vaginal delivery was safely accomplished in 306 (82%). Four uterine ruptures (1.05%) have been reported, only one of which occurred after a single prior unextended low-segment vertical cesarean incision. Two ruptures occurred elsewhere on the lateral or posterior aspect of the uterus in subsequent pregnancies, and the fourth rupture occurred at the juncture of prior low vertical and transverse incisions. No perinatal mortality or permanent perinatal morbidity was encountered with these pregnancies.

CONCLUSIONS

In the otherwise uncomplicated pregnancy the patient with one previous nonextended low-segment vertical cesarean incision should be considered to have a prior low-segment scar and as such be a candidate for trial of labor in her current singleton pregnancy. The same care, counseling, and caution should be exercised for this patient as for one with a prior low-segment transverse incision.