Symptoms and signs with scar rupture--value of uterine activity measurements

How does uterine contractile activity affect the success of trial of labour after caesarean section, and the risk of uterine rupture? An exploratory, blinded analysis of a cohort from a randomised controlled trial

Objective

To investigate the impact of uterine contractile activity on the outcome of trial of labour after caesarean section (TOLAC).

Design

Secondary, blinded analyses of a prospective TOLAC cohort.

Setting

Two labour wards, one in a university tertiary hospital and the other in a central hospital.

Population

A total of 194 TOLAC parturients with intrauterine tocodynamometry during labour.

Methods

Analysis of intrauterine pressure, frequency of contractions and baseline tonus of uterine muscle in 30‐minute periods for 4 hours before birth.

Main outcome measures

Primary outcome: uterine contractile activity during TOLAC. Secondary aims: contributors associated with failed TOLAC and uterine rupture.

Results

TOLAC succeeded in 74% of cases. Uterine contractile activity, expressed as intrauterine pressure, was significantly higher in successful TOLAC compared with failed TOLAC (210 versus 170 Montevideo units). The statistically significant risk factors of failed TOLAC, after multivariate regression analysis, were prolonged gestational age, reduced cervical dilatation at admission and lower mean intrauterine pressure. In cases of uterine rupture, contractile activity did not differ from that in failed TOLAC. Cervical ripening with a Foley catheter appeared to be a risk factor for uterine rupture, as well as cervical dilatation <3 cm at admission. The incidence of total uterine rupture was 2.6% (n = 5).

Conclusions

Women with successful vaginal birth had higher uterine contractile activity than those experiencing failed TOLAC or uterine rupture despite similar use of oxytocin. Induction of labour with a Foley catheter turned out to be a risk factor for uterine rupture during TOLAC among parturients with no previous vaginal delivery.

Tweetable abstract

During VBAC the response to oxytocin, assessed as intrauterine pressure, is greater and adequate, in contrast to failed TOLAC.

During VBAC the response to oxytocin, assessed as intrauterine pressure, is greater and adequate, in contrast to failed TOLAC.

Linked article This article is commented on by PJ Steer, pp. 985 in this issue. To view this minicommentary visit https://doi.org/10.1111/1471-0528.17035.

Tocogram characteristics of uterine rupture: a systematic review

PURPOSE

Timely diagnosing a uterine rupture is challenging. Based on the pathophysiology of complete uterine wall separation, changes in uterine activity are expected. The primary objective is to identify tocogram characteristics associated with uterine rupture during trial of labor after cesarean section. The secondary objective is to compare the external tocodynamometer with intrauterine pressure catheters.

METHODS

MEDLINE, EMBASE, and the Cochrane library were systematically searched for eligible records. Moreover, clinical guidelines were screened. Studies analyzing tocogram characteristics of uterine rupture during trial of labor after cesarean section were appraised and included by two independent reviewers. Due to heterogeneity, a meta-analysis was only feasible for uterine hyperstimulation.

RESULTS

Thirteen studies were included. Three tocogram characteristics were associated with uterine rupture. (1) Hyperstimulation was more frequently observed compared with controls during the delivery (38 versus 21 % and 58 versus 53 %), and in the last 2 h prior to birth (19 versus 4 %). Results of meta-analysis: OR 1.68 (95 % CI 0.97-2.89), p = 0.06. (2) Decrease of uterine activity was observed in 14-40 % and (3) an increasing baseline in 10-20 %. Five studies documented no changes in uterine activity or Montevideo units. A direct comparison between external tocodynamometer and intrauterine pressure catheters was not feasible.

CONCLUSIONS

Uterine rupture can be preceded or accompanied by several types of changes in uterine contractility, including hyperstimulation, reduced number of contractions, and increased or reduced baseline of the uterine tonus. While no typical pattern has been repeatedly reported, close follow-up of uterine contractility is advised and hyperstimulation should be prevented.

A model for educational simulation of the evolution of uterine contractions during labor

Electronic fetal monitoring remains an important tool in labor ward settings, providing continuous information on fetal heart rate and maternal uterine contractions. A prompt detection of abnormalities in these signals is essential for the timely resolution of situations that may put both mother and fetus at risk. Uterine contraction signals provide information that is important to evaluate the onset and progress of labor, as well as the significance of certain fetal heart rate abnormalities. We present a model for educational simulation of the spontaneous evolution of uterine contractions during labor, which combines a previously published signal generator with literature-based pre-programmed scripts for educationally relevant scenarios. This model is an essential component of a high-fidelity simulator of intrapartum emergencies, aimed to improve the competency of healthcare providers. Real and simulated tracings were presented to three independent clinical experts who judged simulated signals to be indistinguishable or negligibly different from real tracings.

Rupture of the uterus in labour: a review of 14 cases in a general hospital

This study aimed to identify the risk factors and clinical presentations associated with rupture of the uterus in labour and to determine material and fetal outcomes. Rupture of the uterus is a potentially devastating complication of childbirth and remains one of the major causes of maternal and perinatal mortality and morbidity.

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.

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.

Extrusion of fetus into the abdominal cavity following complete rupture of uterus: a case report

A gravida 10 para 9, after one Cesarean section (CS) followed by four vaginal deliveries was admitted at term without uterine contractions complaining of abdominal pain. The type of uterine scar was unknown. Severe bradycardia was observed at admission and an emergency Cesarean section was performed. A complete uterine rupture was revealed, the fetus in intact membranes and placenta were found in the abdominal cavity.

Vaginal birth after Caesarean section: an Australian multicentre study. VBAC Study Group

Retrospective analysis of medical records and individual case review was undertaken at 11 major obstetric hospitals for a 5 year period from July 1992 to June 1997 to investigate rates of vaginal birth after Caesarean section (VBAC), the occurrences of uterine rupture, and the outcomes for mother and infant following rupture. Total deliveries were 234,015, of which 21,452 or 9.2% were associated with one or more previous Caesarean sections. Within this scar group, 5419 patients or 25.3% were delivered vaginally. There were 62 cases of significant uterine rupture with no maternal deaths. Perinatal mortality with rupture was 25% and serious maternal complications (usually hysterectomy) occurred in 25% of those with uterine rupture. In women attempting vaginal delivery after a previous lower segment Caesarean section, the uterine rupture rate was estimated at 0.3%, with 0.05% experiencing a perinatal death and 0.05% requiring a hysterectomy. Although VBAC rates in Australia remain lower than many overseas reported series, rates are increasing. While rupture continues to be associated with serious adverse outcomes, the incidence of rupture during trial of labour is low and appears to be associated with a better outcome than rupture of an unscarred uterus.