Single versus double-layer uterine closure at cesarean: impact on lower uterine segment thickness at next pregnancy.

BACKGROUND: Uterine rupture is a potential life-threatening complication during a trial of labor after cesarean delivery. Single-layer closure of the uterus at cesarean delivery has been associated with an increased risk of uterine rupture compared with double-layer closure. Lower uterine segment thickness measurement by ultrasound has been used to evaluate the quality of the uterine scar after cesarean delivery and is associated with the risk of uterine rupture. OBJECTIVE: To estimate the impact of previous uterine closure on lower uterine segment thickness. STUDY DESIGN: Women with a previous single low-transverse cesarean delivery were recruited at 34-38 weeks' gestation. Transabdominal and transvaginal ultrasound evaluation of the lower uterine segment thickness was performed by a sonographer blinded to clinical data. Previous operative reports were reviewed to obtain the type of previous uterine closure. Third-trimester lower uterine segment thickness at the next pregnancy was compared according to the number of layers sutured and according to the type of thread for uterine closure, using weighted mean differences and multivariate logistic regression analyses. RESULTS: Of 1613 women recruited, with operative reports available, 495 (31%) had a single-layer and 1118 (69%) had a double-layer closure. The mean third-trimester lower uterine segment thickness was 3.3 ± 1.3 mm and the proportion with lower uterine segment thickness <2.0 mm was 10.5%. Double-layer closure of the uterus was associated with a thicker lower uterine segment than single-layer closure (weighted mean difference: 0.11 mm; 95% confidence interval [CI], 0.02 to 0.21 mm). In multivariate logistic regression analyses, a double-layer closure also was associated with a reduced risk of lower uterine segment thickness <2.0 mm (odd ratio [OR], 0.68; 95% CI, 0.51 to 0.90). Compared with synthetic thread, the use of catgut for uterine closure had no significant impact on third-trimester lower uterine segment thickness (WMD: -0.10 mm; 95% CI, -0.22 to 0.02 mm) or on the risk of lower uterine segment thickness <2.0 mm (OR, 0.95; 95% CI, 0.67 to 1.33). Finally, double-layer closure was associated with a reduced risk of uterine scar defect (RR, 0.32; 95% CI, 0.17 to 0.61) at birth. CONCLUSION: Compared with single-layer closure, a double-layer closure of the uterus at previous cesarean delivery is associated with a thicker third-trimester lower uterine segment and a reduced risk of lower uterine segment thickness <2.0 mm in the next pregnancy. The type of thread for uterine closure has no significant impact on lower uterine segment thickness.

Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study.

BACKGROUND: Choice of delivery route after previous cesarean delivery can be difficult because both trial of labor after cesarean delivery and elective repeat cesarean delivery are associated with risks. The major risk that is associated with trial of labor after cesarean delivery is uterine rupture that requires emergency laparotomy. OBJECTIVE: This study aimed to estimate the occurrence of uterine rupture during trial of labor after cesarean delivery when lower uterine segment thickness measurement is included in the decision-making process about the route of delivery. STUDY DESIGN: In 4 tertiary-care centers, we prospectively recruited women between 34 and 38 weeks of gestation who were contemplating a vaginal birth after a previous single low-transverse cesarean delivery. Lower uterine segment thickness was measured by ultrasound imaging and integrated in the decision of delivery route. According to lower uterine segment thickness, women were classified in 3 risk categories for uterine rupture: high risk (<2.0 mm), intermediate risk (2.0-2.4 mm), and low risk (≥2.5 mm). Our primary outcome was symptomatic uterine rupture, which was defined as requiring urgent laparotomy. We calculated that 942 women who were undergoing a trial of labor after cesarean delivery should be included to be able to show a risk of uterine rupture <0.8%. RESULTS: We recruited 1856 women, of whom 1849 (99%) had a complete follow-up data. Lower uterine segment thickness was <2.0 mm in 194 women (11%), 2.0-2.4 mm in 217 women (12%), and ≥2.5 mm in 1438 women (78%). Rate of trial of labor was 9%, 42%, and 61% in the 3 categories, respectively (P<.0001). Of 984 trials of labor, there were no symptomatic uterine ruptures, which is a rate that was lower than the 0.8% expected rate (P=.0001). CONCLUSION: The inclusion of lower uterine segment thickness measurement in the decision of the route of delivery allows a low risk of uterine rupture during trial of labor after cesarean delivery.

Adverse obstetric outcomes in women with previous cesarean for dystocia in second stage of labor.

OBJECTIVE: To evaluate obstetric outcomes in women undergoing a trial of labor (TOL) after a previous cesarean for dystocia in second stage of labor. METHODS: A retrospective cohort study of women with one previous low transverse cesarean undergoing a first TOL was performed. Women with previous cesarean for dystocia in first stage and those with previous dystocia in second stage were compared with those with previous cesarean for nonrecurrent reasons (controls). Multivariable regressions analyses were performed. RESULTS: Of 1655 women, those with previous dystocia in second stage of labor (n = 204) had greater risks than controls (n = 880) to have an operative delivery [odds ratio (OR): 1.5; 95% confidence intervals (CI) 1.1 to 2.2], shoulder dystocia (OR: 2.9; 95% CI 1.1 to 8.0), and uterine rupture in the second stage of labor (OR: 4.9; 95% CI 1.1 to 23), and especially in case of fetal macrosomia (OR: 29.6; 95% CI 4.4 to 202). The median second stage of labor duration before uterine rupture was 2.5 hours (interquartile range: 1.5 to 3.2 hours) in these women. CONCLUSION: Previous cesarean for dystocia in the second stage of labor is associated with second-stage uterine rupture at next delivery, especially in cases of suspected fetal macrosomia and prolonged second stage of labor.

Impact of labor at prior cesarean on lower uterine segment thickness in subsequent pregnancy.

OBJECTIVE: The objective of the study was to identify the factors associated with sonographic lower uterine segment (LUS) thickness near term in women with prior low transverse cesarean. STUDY DESIGN: A prospective cohort study of women with a single prior low transverse cesarean was conducted. LUS thickness was quantified by transabdominal ultrasound with repeated transvaginal measurement when necessary. The thinnest measurement was considered as the dependent variable. Potential related factors were evaluated with nonparametric analyses and multivariate logistic regressions. RESULTS: Two hundred thirty-five women were recruited at a mean gestational age of 36.7 +/- 1.3 weeks. The full LUS was thicker in women who had their previous cesarean during the latent phase (2.8 mm; interquartile [IQ], 2.0-3.3 mm) or the active phase of labor (3.1 mm; IQ 2.5-3.9 mm) than in women with previous cesarean prior to labor (2.4 mm; IQ 2.0-3.2 mm). The association remained significant after adjustment for potential confounders. CONCLUSION: Presence of labor at previous cesarean is associated with a thicker LUS in a subsequent pregnancy.

[Measurement of the lower uterine segment: are we ready for a clinical application?]. / Mesure du segment inférieur utérin : sommes-nous prêts pour une application clinique ?

The measurement of the lower uterine segment (LUS) seems to be the best technique available to estimate the risk of uterine rupture, but there is a great heterogeneity in the techniques used. It appears necessary to standardize the interventions and their teaching prior to extending the use of the LUS measurement to clinical settings beyond well-defined research purposes.

Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment.

OBJECTIVE: The purpose of this study was to establish the validity of sonographic evaluation of lower uterine segment (LUS) thickness for complete uterine rupture. STUDY DESIGN: A prospective cohort study of women with previous cesarean delivery was conducted. LUS thickness (full thickness and myometrial thickness only) was measured between 35 and 38 weeks gestation, and the thinnest measurement was considered to be the dependent variable. Receiver operating curve analyses and logistic regression were used. RESULTS: Two hundred thirty-six women were included in the study. Nine uterine scar defects (3 cases of complete rupture during a trial of labor and 6 cases of dehiscence) were reported. Receiver operating curve analyses showed that full thickness of <2.3 mm was the optimal cutoff for the prediction of uterine rupture (3/33 vs 0/92; P = .02). Full thickness was also identified as an independent predictor of uterine scar defect (odds ratio, 4.66; 95% confidence interval, 1.04-20.91) CONCLUSION: Full LUS thickness of <2.3 mm is associated with a higher risk of complete uterine rupture.

Mid-trimester genetic amniocentesis in twin pregnancy and the risk of fetal loss.

OBJECTIVE: To assess the rate of fetal losses in twin pregnancies undergoing genetic mid-trimester amniocentesis. METHODS: In the first part of this investigation, a retrospective cohort study compared a group of women . 32 years old with twin pregnancies who underwent amniocentesis with a similar group unexposed to amniocentesis. Data were compiled from January 1990 to March 2004 for patients from a single institution. Pregnancies complicated by twin-to-twin transfusion syndrome, monoamniotic twins, or lethal fetal anomalies, and those treated by fetal reduction were excluded. The primary outcome was the loss of one or both fetuses prior to 24 weeks' gestation. In the second part of the investigation, a systematic review of the literature and a meta-analysis were performed. RESULTS: In the first part of the study, data were collected for 132 women exposed to amniocentesis and 248 women not exposed to amniocentesis. There was no significant difference in the rate of fetal losses between the two groups (3.0% vs. 0.8%, P = 0.10). No losses occurred within four weeks of the procedure. In the second part of the investigation, four studies, including ours, were considered for a meta-analysis of 2026 women with twin pregnancies. Compared with women unexposed to the procedure, amniocentesis in women with twin pregnancies increased the risk of fetal losses prior to 20 to 24 weeks' gestation (odds ratio 2.42; 95% confidence intervals 1.24-4.74, P = 0.01) with an additional risk of one adverse outcome (1 or 2 fetal losses) for every 64 amniocenteses. CONCLUSION: Genetic mid-trimester amniocentesis in twin pregnancies is associated.

Obstetrical and neonatal outcomes following unsuccessful external cephalic version: a stratified analysis amongst failures, successes, and controls.

OBJECTIVE: Though on average one out of every two external cephalic versions (ECV) fails to rotate the breech fetus, little is known about the outcomes of pregnancies in which ECV is unsuccessful. The objective of the present study is to compare obstetrical and neonatal outcomes following failure of ECV, relative to cases of breech controls without an attempt at ECV. STUDY DESIGN: We conducted a retrospective, population-based, cohort study using the CDC's Birth Data files from the US for the year 2006. We stratified the cohort according to fetal presentation and ECV status: success, failure, and no ECV (controls). The effect of failure of ECV on the risk of several neonatal and obstetrical outcomes was estimated using logistic regression analysis, adjusting for relevant confounders. RESULTS: We analyzed a total of 4 273 225 births, out of which 183 323 (4.3%) met inclusion criteria. Relative to breech controls, failed ECV occurred more frequently amongst Caucasian, college-educated, married women bearing a female fetus. Compared to no ECV, failure of ECV was associated with increased odds of PROM (aOR, 1.75; 95% CI, 1.60-1.90), elective cesarean delivery (aOR, 1.53; 95% CI, 1.36-1.72), cesarean delivery in labor (aOR, 1.38; 95% CI, 1.21-1.57), abnormal fetal heart tracing (aOR, 1.78; 95% CI, 1.50-2.11), assisted ventilation at birth (aOR, 1.50; 95% CI, 1.27-1.78), 5-min APGAR scores <7 (aOR, 1.35; 95% CI, 1.20-1.51), and NICU admission (aOR, 1.48; 95% CI, 1.20-1.82). The delayed spontaneous fetal restitution rate was 13%. When stratifying controls with regards to trial of labor status, the increased risk of failed ECV persisted for cesarean delivery, NICU admission, assisted ventilation and abnormal fetal tracing, independently of whether a trial of labor took place. CONCLUSION: Relative to breech controls without attempt at ECV, failure of ECV to restitute cephalic presentation appears to be associated with an increased risk of adverse perinatal and obstetrical outcomes.

Cervical ripening with transcervical foley catheter and the risk of uterine rupture.

OBJECTIVE: To estimate whether the rate of uterine rupture in patients with a previous cesarean delivery is related to labor induction and/or cervical ripening using transcervical Foley catheter. METHODS: Charts of all patients who had a trial of labor after a previous cesarean delivery in our institution between 1988 and 2002 were reviewed. The rates of successful vaginal birth after cesarean delivery and uterine rupture in patients with spontaneous labor (control group) were compared with those of patients who underwent a labor induction by means of amniotomy with or without oxytocin and patients who underwent a labor induction/cervical ripening using a transcervical Foley catheter. Logistic regression analysis was performed to adjust for confounding variables. RESULTS: Of 2479 patients, 1807 had a spontaneous labor, 417 had labor induced by amniotomy with or without oxytocin, and 255 had labor induced by using transcervical Foley catheter. The rate of successful vaginal birth after cesarean delivery was significantly different among the groups (78.0% versus 77.9% versus 55.7%, P <.001), but not the rate of uterine rupture (1.1% versus 1.2% versus 1.6%, P =.81). After adjusting for confounding variables, the odds ratio (OR) for successful vaginal birth after cesarean delivery was 0.68 (95% confidence interval [CI] 0.41, 1.15), and the OR for uterine rupture was 0.47 (95% CI 0.06, 3.59) in patients who underwent an induction of labor using a transcervical Foley catheter when compared with patients with spontaneous labor. CONCLUSION: Labor induction using a transcervical Foley catheter was not associated with an increased risk of uterine rupture.

Twin delivery after a previous caesarean: a twelve-year experience.

OBJECTIVES: To compare maternal and neonatal morbidities between trial of labour (TOL) and elective Caesarean section in women with twin pregnancies who have had a prior Caesarean. METHODS: An observational study was conducted of women with a prior Caesarean who delivered twins at 28 weeks gestation or greater in Ste-Justine Hospital between 1988 and 2001. Maternal and neonatal outcomes were compared between women who had a TOL (group 1) and those who had an elective Caesarean delivery (group 2). RESULTS: Twenty-six women and 52 fetuses were included in group 1 and compared to the 71 women and 142 fetuses in group 2. Maternal age, gestational age, and birth weight were comparable in both groups. In group 1, 22 (85%) out of 26 women delivered twin A vaginally and 19 (73%) delivered both vaginally. There was no significant difference in the umbilical artery cord pH, Apgar score, ventilatory support, and admission to the neonatal intensive care unit between the 2 groups. There was also no significant difference in the rate of postpartum maternal fever or decrease of serum hemoglobin between the 2 groups, but the median hospital stay was higher in the group with elective Caesarean (5.0 vs. 3.0 days, p <0.001). There were no uterine ruptures or other major complications in either group. CONCLUSION: There were no significant differences in maternal and neonatal morbidity outcomes between births by trial of labour and by elective Caesarean, in twin pregnancies after a prior Caesarean section. A trial of labour is associated with a shorter hospital stay.

Single- versus double-layer closure of the hysterotomy incision during cesarean delivery and risk of uterine rupture.

OBJECTIVE: To evaluate the best available evidence regarding the association between single-layer closure and uterine rupture. METHODS: The PubMed, Embase, and Cochrane Central Register of Controlled Trials databases were searched for relevant observational and experimental studies that included women with a previous single, low, transverse cesarean delivery who had attempted a trial of labor (TOL). The risks of uterine rupture and uterine dehiscence were assessed by pooled odds ratios (OR) calculated with a random effects model. RESULTS: Nine studies including 5810 women were reviewed. Overall, the risk of uterine rupture during TOL after a single-layer closure was not significantly different from that after a double-layer closure (OR 1.71; 95% confidence interval [CI] 0.66-4.44). However, a sensitivity analysis indicated that the risk of uterine rupture was increased after a locked single-layer closure (OR 4.96; 95% CI 2.58-9.52, P<0.001) but not after an unlocked single-layer closure (OR 0.49; 95% CI 0.21-1.16), compared with a double-layer closure. CONCLUSION: Locked but not unlocked single-layer closures were associated with a higher uterine rupture risk than double-layer closure in women attempting a TOL.

Risk of uterine rupture associated with an interdelivery interval between 18 and 24 months.

OBJECTIVE: To estimate the association between interdelivery interval and uterine rupture in women with a previous cesarean delivery. METHODS: Secondary analysis was performed in a retrospective cohort study of women who underwent a trial of labor after undergoing a previous cesarean delivery. Only singleton pregnancies with a trial of labor at term were included. Women with two or more previous cesarean deliveries or with a vaginal delivery between the cesarean delivery and the trial of labor were excluded. The rates of uterine rupture were compared among women with interdelivery intervals 24 months or longer (controls), 18-24 months, and fewer than 18 months. The chi2 test and multivariable logistic regression analysis were conducted. A P value of less than .05 was considered significant. RESULTS: A total of 1,768 women were included: 1,323 (74.8%) were 24 months or longer, 257 (14.5%) were 18-23 months, and 188 (10.6%) were fewer than 18 months. The rates of uterine rupture were 1.3%, 1.9%, and 4.8%, respectively (P=.003). After adjustment for confounding factors, an interdelivery interval shorter than 18 months was associated with a significant increase of uterine rupture (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.3-7.2), whereas an interdelivery interval between 18 to 24 months was not (OR, 1.1; 95% CI, 0.4-3.2). CONCLUSION: An interdelivery interval shorter than 18 months, but not between 18 and 24 months, should be considered as a risk factor for uterine rupture.

Effect of birth weight on adverse obstetric outcomes in vaginal birth after cesarean delivery.

OBJECTIVE: To estimate the association between neonatal birth weight and adverse obstetric outcomes in women attempting vaginal birth after cesarean. METHODS: We reviewed the medical records of all women undergoing a trial of labor after a prior low transverse cesarean delivery in our institution between 1987 and 2004. Patients were categorized according to birth weight (less than 3,500 g [group 1, reference], 3,500-3,999 g [group 2], and 4,000 g or more [group 3]) and prior vaginal delivery. The rates of failed trial of labor, uterine rupture, shoulder dystocia, and third- and fourth-degree perineal laceration were compared among groups. Multivariable logistic regressions were performed to adjust for potential confounding factors. RESULTS: Of 2,586 women, 1,519 (59%), 798 (31%), and 269 (10%) were included in groups 1, 2, and 3, respectively. Birth weight was directly correlated to the rate of failed trial of labor (19%, 28%, and 38% for groups 1, 2, and 3, respectively; P<.01), uterine rupture (0.9%, 1.8%, and 2.6%; P<.05), shoulder dystocia (0.3%, 1.6%, and 7.8%; P<.01), and third- and fourth-degree perineal laceration (5%, 7%, and 12%; P<.01). After adjustment for confounding variables, birth weight of 4,000 g or more remained associated with uterine rupture (odds ratio [OR] 2.62, 95% confidence interval [CI] 1.001-6.85), failed trial of labor (OR 2.47, 95% CI 1.82-3.34), shoulder dystocia (OR 25.13, 95% CI 9.31-67.86), and third- and fourth-degree perineal laceration (OR 2.64, 95% CI 1.66-4.19). CONCLUSION: Birth weight and specifically macrosomia are linked with failed trial of labor, uterine rupture, shoulder dystocia, and third- and fourth-degree perineal laceration in women who underwent prior cesarean delivery. Estimated fetal weight should be included in the decision-making process for all women contemplating a trial of labor after cesarean delivery. LEVEL OF EVIDENCE: II.

The role of uterine closure in the risk of uterine rupture.

OBJECTIVE: To evaluate the effects of prior single-layer compared with double-layer closure on the risk of uterine rupture. METHODS: A multicenter, case-control study was performed on women with a single, prior, low-transverse cesarean who experienced complete uterine rupture during a trial of labor. For each case, three women who underwent a trial of labor without uterine rupture after a prior low-transverse cesarean delivery were selected as control participants. Risk factors such as prior uterine closure, suture material, diabetes, prior vaginal delivery, labor induction, cervical ripening, birth weight, prostaglandin use, maternal age, gestational age, and interdelivery interval were compared between groups. Conditional logistic regression analyses were conducted. RESULTS: Ninety-six cases of uterine rupture, including 28 with adverse neonatal outcome, and 288 control participants were assessed. The rate of single-layer closure was 36% (35 of 96) in the case group and 20% (58 of 288) in the control group (P<.01). In multivariable analysis, single-layer closure (odds ratio [OR] 2.69; 95% confidence interval [CI] 1.37-5.28) and birth weight greater than 3,500 g (OR 2.03; 95% CI 1.21-3.38) were linked with increased rates of uterine rupture, whereas prior vaginal birth was a protective factor (OR 0.47; 95% CI 0.24-0.93). Single-layer closure was also related to uterine rupture associated with adverse neonatal outcome (OR 2.89; 95% CI 1.01-8.27). CONCLUSION: Prior single-layer closure carries more than twice the risk of uterine rupture compared with double-layer closure. Single-layer closure should be avoided in women who could contemplate future vaginal birth after cesarean delivery. LEVEL OF EVIDENCE: II.

Neonatal morbidity associated with uterine rupture: what are the risk factors?

OBJECTIVE: The purpose of this study was to evaluate factors associated with severe metabolic acidosis or death in a situation of uterine rupture. STUDY DESIGN: A retrospective study was performed with review of charts and electronic monitoring strips. RESULTS: Between November 1988 and November 2000, a total of 23 cases of complete uterine rupture were identified from among 2233 trials of labor after a previous low transverse cesarean delivery. Nine neonates (39.1%) had severe metabolic acidosis (pH < 7.0); among these, hypoxic-ischemic encephalopathy was diagnosed in 3 neonates and another neonate died. Placental or fetal extrusion or both were associated with severe metabolic acidosis (P <.001) but not with the other factors (birth weight, induction of labor, use of oxytocin, use of epidural, and cervix dilatation). Two newborns with severe acidosis had impaired motor development even with an intervention time less than 18 minutes from the onset of prolonged deceleration to delivery. CONCLUSION: When uterine rupture occurs, placental or fetal extrusion was the most important factor associated with severe metabolic acidosis. Prompt intervention did not always prevent severe metabolic acidosis and neonatal morbidity.

Interdelivery interval and uterine rupture.

OBJECTIVE: The purpose of this study was to measure the impact of the interdelivery interval on uterine rupture during subsequent delivery. STUDY DESIGN: An observational cohort study was performed to assess the rate of uterine rupture in women with a previous low transverse cesarean delivery and no previous vaginal delivery who undergo a trial of labor from 1988 to 2000 in a tertiary care center. The rate of uterine rupture was measured for each of the following interdelivery intervals: 36 months of gestation. Multivariate logistic regression analysis was used to adjust for selected confounding variables. RESULTS: Of the 1527 women who met the study criteria, the rate of uterine rupture was 4.8% for patients with an interdelivery interval of 36 months of gestation (P =.04). After adjustment for the confounding variables, the odds ratio for uterine rupture in women with an interdelivery interval of 24 months of gestation.