True rupture/scar dehiscence in delivery following prior section

Ultrasound Evaluation of the Uterine Scar After Cesarean Delivery

OBJECTIVE

To survey the uterine scar thickness by ultrasonography in women randomly assigned to one- or two-layer hysterotomy closure after primary cesarean delivery.

METHODS

This was a randomized, blinded trial of uterine scar closure with ultrasonographic follow-up. Thirty consecutive patients undergoing primary cesarean delivery were enrolled and randomly assigned to one- or two-layer closure of the hysterotomy. Ultrasound surveillance of the uterine scar thickness was performed at baseline (before surgery) and 48 hours, 2 weeks, and 6 weeks post partum.

RESULTS

Patient compliance with the postpartum surveillance protocol was 90%, and the uterine scar was visualized in 99% of attempted ultrasonographic examinations. There were no differences between groups at baseline or at any of the follow-up evaluations. An initial 5- to 6-fold increase in uterine scar thickness was observed, followed by a gradual decrease with the 6-week measurements still thicker than baseline. Repeated measures analysis of variance showed significant variation across time points starting either at baseline (P<.001) or at 48 hour postoperatively (P<.001), but this variation did not depend on closure type (P=.79 for all visits and P=.81 beginning with 48-hour postoperative time point).

CONCLUSION

The process of uterine scar remodeling can be successfully monitored by ultrasonography. Uterine scar thickness diminishes progressively after both one- or two-layer closure but does not vary with mode of hysterotomy closure. The uterine scar thickness remains increased even at 6 weeks post partum, suggesting that the process of uterine scar remodeling extends beyond the traditional postpartum period. CLINCAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00224250

Laparoscopic and vaginal repair of uterine scar dehiscence following cesarean section as detected by ultrasound

INTRODUCTION AND OBJECTIVE

Cesarean section (CS) is the most common operation in obstetrics, with rising incidence in most countries. As a result of this operation late scar dehiscence may occur, which may lead to uterine rupture in a subsequent pregnancy. In this case series we have described sonographic detection of scar dehiscence after CS and feasibility of vaginal or combined laparoscopic and vaginal scar excision and uterine repair.

METHODS

Five consecutive patients underwent vaginal or laparoscopic assisted vaginal approach for repair of suspected scar dehiscence following CS, during a 5 year period. In all cases, transvaginal sonography detected suspicious features of scar dehiscence over the anterior uterine wall. Except of one, all patients had reported recurrent pelvic pain and/or irregular menstrual bleedings. Furthermore all patients planned for a further pregnancy.

RESULTS

Resection of the uterine defect and re-constitution of the uterine wall was successfully achieved in all five patients. There were no intra-operative complications and none of the patients required blood transfusion. The mean operation time was 117 min (27-192). Presence of scar tissue was confirmed on histology in all specimens. Four patients remained free of symptoms with no evidence of recurrent scar dehiscence on sonography over a median follow up of 30 months (3-46). One patient had an uneventful pregnancy 24 months after scar removal and was delivered by repeat CS at 39 weeks' gestation.

CONCLUSION

Patients with a history of CS should undergo transvaginal sonography of the scar region in order to detect latent scar dehiscence in combination with uterine wall thinning prior to planning further pregnancy. In suspected cases, a combined laparoscopic - vaginal or vaginal approach can be employed to repair the defect.

Cesarean section scar evaluation by saline contrast sonohysterography

OBJECTIVE

To investigate the frequency of images suggesting the existence of a dehiscence at the site of the uterine scar after Cesarean section.

METHODS

Thirty-three women with a past history of Cesarean section who were planning a further pregnancy were involved in the study. Saline contrast sonohysterography (SCSH) was performed a minimum of 3 months following Cesarean section. The thickness of the residual myometrium, the thickness of the myometrium bordering the scar and the depth of the filling defect in the scar (i.e. the 'niche', defined as a triangular, anechoic area at the presumed site of incision) were recorded in each case. A 'dehiscence' was defined as a niche whose depth was at least 80% of the anterior myometrium.

RESULTS

In 19/33 (57.5%) patients a niche with a depth of 4.2 +/- 2.5 (range, 1.2-11.7) mm was identified. In these patients the residual myometrium measured 6.5 +/- 2.7 (range, 0-10.9) mm vs. 8.9 +/- 2.0 (range, 6.9-13.9) mm in the remaining 14 patients without a niche. Within the 19 niches, two dehiscences were identified.

CONCLUSION

Niches can be identified by SCSH following a Cesarean section in about 60% of patients. The prevalence of scar dehiscence (in the present series 2/33 or 6%) is much higher than the reported risk of uterine rupture (0.4%).

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.

Characteristics of fetal heart rate tracings prior to uterine rupture

OBJECTIVE

To identify the fetal heart rate patterns that occurred in a 2-h period of time preceding uterine rupture.

METHODS

The fetal monitor strips and the medical records of patients with a confirmed diagnosis of uterine rupture were reviewed. These patients delivered at the University of Michigan Hospital from January 1, 1985 to December 31, 1999 and were >or =28 weeks gestational age. Asymptomatic uterine scar dehiscences were excluded. The weeks of gestation, the number of cesarean sections, the surgical findings, and the maternal complications were obtained from the review of the maternal records. The fetal monitor strips for the 2 h preceding the uterine rupture were analyzed, and the fetal heart rate patterns were classified.

RESULTS

During the study period, there were 11 patients identified with uterine rupture. Seven of the 11 (64%) had operative or post-operative complications. There were no maternal deaths. Review of the eight fetal heart rate tracings available revealed 7/8 (87.5%) with recurrent late decelerations and 4/8 (50%) with terminal bradycardia. All four of the patients with fetal bradycardia were preceded by recurrent late decelerations (100%).

CONCLUSIONS

The most common fetal heart rate abnormalities that occurred prior to uterine rupture were recurrent late decelerations and bradycardia. The appearance of recurrent late decelerations may be an early sign of impending uterine rupture.

Elective repeat cesarean delivery versus trial of labor: a meta-analysis of the literature from 1989 to 1999

OBJECTIVE

The aim of this study was to compare a trial of labor with elective repeat cesarean delivery among women with previous cesarean delivery.

STUDY DESIGN

We searched MEDLINE and EMBASE databases from 1989 through 1999 with the following terms: vaginal birth after cesarean delivery, trial of labor, trial of scar, and uterine rupture. We included all controlled trials from developed countries in which the control group had been eligible for a trial of labor. Outcomes of interest were uterine rupture, hysterectomy, maternal febrile morbidity, maternal mortality, 5-minute Apgar score <7, and fetal or neonatal mortality. We computed pooled odds ratios for each outcome.

RESULTS

The search strategy identified 52 controlled studies, 37 of which were excluded because many of the control subjects were not eligible for a trial of labor. Fifteen studies with a total of 47,682 women were included. Uterine rupture occurred more frequently among women undergoing a trial of labor than among those undergoing elective repeat cesarean delivery (odds ratio, 2.10; 95% confidence interval, 1.45-3.05). There was no difference in maternal mortality risk between the 2 groups (odds ratio, 1.52; 95% confidence interval, 0.36-6.38). Fetal or neonatal death (odds ratio, 1.71; 95% confidence interval, 1.28-2.28) and 5-minute Apgar scores <7 (odds ratio, 2.24; 95% confidence interval, 1.29-3.88) were more frequent in the trial of labor group than in the control group. Mothers undergoing a trial of labor were less likely to have febrile morbidity (odds ratio, 0.70; 95% confidence interval, 0.64-0.77) or to require transfusion (odds ratio, 0.57; 95% confidence interval, 0.42-0.76) or hysterectomy (odds ratio, 0.39; 95% confidence interval, 0.27-0.57).

CONCLUSION

A trial of labor may result in small increases in the uterine rupture rate and in fetal and neonatal mortality rates with respect to elective repeat cesarean delivery. Maternal morbidity, including febrile morbidity, and the need for transfusion or hysterectomy may be reduced with a trial of labor.

External cephalic version after previous cesarean section: a series of 38 cases

OBJECTIVE

To determine if external cephalic version (ECV) is a reasonable alternative to repeat cesarean section in case of breech presentation.

STUDY DESIGN

Retrospective study of 38 women with one previous cesarean section and a breech presentation after 36 weeks of gestational age who have had at least one experience of ECV. Statistics used the Fisher's test with significance when P<0.05.

RESULTS

Version attempts were successful in 25 of the 38 women (65.8%). Seventy-six percent of the successful version women went on to have vaginal birth after cesarean section. A total of 19 successful vaginal deliveries occurred (50%). Success rate of ECV was lowered when breech was the indication of the previous cesarean section. The vaginal delivery rate was increased after successful ECV in patients previously vaginally delivered, but this difference did not reached significance (P=0.057). No maternal or neonatal complications occurred.

CONCLUSION

ECV is acceptable and effective in women with a prior low transverse uterine scar, when safety criteria are observed.

Routine revision of uterine scar after cesarean section: has it ever been necessary?

Although a trial of labor after cesarean section (VBAC) is successful and relatively safe, few studies have directly addressed the necessity of routine transcervical revision of uterine scar after prior cesarean section. We performed a longitudinal study of 3469 women who had VBAC. In all patients, uterine scar integrity was examined immediately after placental expulsion. The detection rate of uterine scar dehiscence or rupture was 0.23% (8/3469). Only one woman with complete uterine rupture needed immediate laparotomy for severe hemorrhage. Out of seven patients (0.2%), who had evidence of uterine dehiscence, three underwent explorative laparotomy. In conclusion, the potential benefit of routine examination of uterine scar after VBAC is doubtful. Transcervical revision should be performed only in symptomatic patients.

Obstetric outcome after one previous caesarean section

OBJECTIVE

A prospective study was undertaken to evaluate the outcome of trial of labour (TOL) after one previous cesarean section.

METHODS

A total of 2,447 deliveries were conducted during this study period over 22 months. Out of these patients 167 women had one previous cesarean birth, 112 (67.1%) of whom underwent trial of labour.

RESULTS

Seventy-two (64.28%) of these patients achieved vaginal delivery. This success rate would be much higher if fixed protocol could be applied to all the patients. Fourty-six point fifteen percent of patients with past indication for cesarean section due to cephalopelvic disproportion also delivered vaginally. This advocates that each patient should be selected on individual merits and the past indication for cesarean section should be reviewed. One maternal death occurred in this study which was due to anaesthetic complication while the perinatal mortality rate in this group was slightly higher as compared to national perinatal mortality rate, reason discussed in the text.

CONCLUSION

It is safe to offer TOL provided patient is carefully selected and monitored.

Transvaginal surgery for uterine scar dehiscence

Asymptomatic uterine rupture, usually discovered during routine uterine examination because of a pre-existing uterine scar, it treated by techniques that include suturing the dehiscence via abdominal access, total or subtotal hysterectomy or therapeutic non-intervention. The authors propose a transvaginal technique.

The relationship between gestational age and the incidence of classical caesarean section

Improved neonatal survival has led to a rise in the number of Caesarean sections being performed in the presence of extreme prematurity. Many of these operations require an incision in the upper uterine segment with consequent ramifications for the management of any subsequent pregnancy. In this analysis of obstetric patients in a tertiary referral institution over a 9-year period, there was an overall Caesarean section rate of 18%. A classical incision was performed in 1% of all caesarean sections, but at 24 weeks' gestation, 20% of Caesarean sections were 'classical'. This frequency decreased to less than 5% at 30 weeks and less than 1% from 34 weeks' gestation. Most women having a classical Caesarean section at term had either a transverse lie or a major degree of placenta praevia.

Ultrasonographic measurement of lower uterine segment to assess risk of defects of scarred uterus

BACKGROUND

Ultrasonography has been used to examine the scarred uterus in women who have had previous caesarean sections in an attempt to assess the risk of rupture of the scar during subsequent labour. The predictive value of such measurements has not been adequately assessed, however. We aimed to evaluate the usefulness of sonographic measurement of the lower uterine segment before labour in predicting the risk of intrapartum uterine rupture.

METHODS

In this prospective observational study, the obstetricians were not told the ultrasonographic findings and did not use them to make decisions about type of delivery. Eligible patients were those with previous caesarean sections booked for delivery at our hospital. 642 patients underwent ultrasound examination at 36-38 weeks' gestation, and were allocated to four groups according to the thickness of the lower uterine segment. Ultrasonographic findings were compared with those of physical examination at delivery.

FINDINGS

The overall frequency of defective scars was 4.0% (15 ruptures, 10 dehiscences). The frequency of defects rose as the thickness of the lower uterine segment decreased: there were no defects among 278 women with measurements greater than 4.5 mm, three (2%) among 177 women with values of 3.6-4.5 mm, 14 (10%) among 136 women with values of 2.6-3.5 mm, and eight (16%) among 51 women with values of 1.6-2.5 mm. With a cut-off value of 3.5 mm, the sensitivity of ultrasonographic measurement was 88.0%, the specificity 73.2%, positive predictive value 11.8%, and negative predictive value 99.3%.

INTERPRETATION

Our results show that the risk of a defective scar is directly related to the degree of thinning of the lower uterine segment at around 37 weeks of pregnancy. The high negative predictive value of the method may encourage obstetricians in hospitals where routine repeat elective caesarean is the norm to offer a trial of labour to patients with a thickness value of 3.5 mm or greater.

Rupture of the uterus

OBJECTIVES

To investigate the frequency of ruptured uterus, possible etiologic factors and fetomaternal outcomes.

METHODS

The birth records of 58262 deliveries at Dr Zekai Tahir Burak Women's Hospital from 1 January 1990 to 31 December 1992 were reviewed and the results compared with those of two previous studies reported from this hospital on the same subject.

RESULTS

Forty uterine ruptures occurred between 1990 and 1992, with a frequency of 0.068% (1/1457). All occurred spontaneously but 10 (25%) had no previous surgery, whereas 30 followed previous cesarean section. There was no traumatic uterine rupture during this period. Fetal mortality was 32.5% and no maternal deaths were recorded.

CONCLUSION

The rate of ruptured uterus has declined among our hospital population as etiologic factors responsible for the complication have been reduced.

Detection of scar dehiscence at delivery in women with prior cesarean section

Transcervical examination of a prior cesarean scar after vaginal delivery is commonly advised. A retrospective study of 1023 parturients with prior cesarean delivery was undertaken, 475 of whom delivered vaginally. Thirteen cases of scar dehiscence were found at laparotomy, and only one case was discovered by transcervical examination. The value of routine postdelivery examination of uterine scar is doubtful.

Vaginal birth after cesarean section: the impact of patient resistance to a trial of labor

In spite of the relative safety and medical advantages of vaginal birth after cesarean section, the procedure continues to be underutilized in the private practice setting. To evaluate the hypothesis that resistance by the patient often precludes a trial of labor, an observational study was conducted of all women with a history of one prior cesarean section who were delivered in 1989 at Ochsner Foundation Hospital. The choices of 167 women and the judgments of their obstetricians were longitudinally recorded during the antepartum and intrapartum course. Patients routinely received the patient guide of the American College of Obstetricians and Gynecologists for vaginal birth after cesarean section. Ultimately, 50% of patients who were encouraged by their obstetrician toward vaginal birth after cesarean section opted for an elective repeat cesarean section without a trial of labor. Reasons for patient resistance are enumerated and potential future remedial proposals are discussed.