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Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study
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Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study Q7
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Nicole Jastrow, MD; Suzanne Demers, MD; Nils Chaillet, PhD; Mario Girard, ; Robert J. Gauthier, MD; Jean-Charles Pasquier, MD, PhD; Belkacem Abdous, PhD; Chantale Vachon-Marceau, MD; Sylvie Marcoux, MD, PhD; Olivier Irion, MD; Normand Brassard, MD; Michel Boulvain, MD, PhD; Emmanuel Bujold, MD, MSc
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 (less than 2.0 mm), intermediate risk (2.0e2.4 mm), and low risk (2.5 mm). Our primary outcome was symptomatic uterine
I
n the last 3 decades, the rate of cesarean deliveries has been rising continuously worldwide and has reached >30% in many countries. A major contributor to this trend is the concomitant decline in the percentage of trial of labor after cesarean delivery (TOLAC) and vaginal birth after cesarean delivery (VBAC).1 Fear of intrapartum uterine rupture, a rare (0.4e1.1%) but potentially catastrophic complication of TOLAC, represents the main reason for this trend.2 Uterine rupture can lead to perinatal asphyxia or death and severe maternal complications.3,4 The alternative for TOLAC is to
Cite this article as: Jastrow N, Demers S, Chaillet N, et al. Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study. Am J Obstet Gynecol 2016;:. 0002-9378/$36.00 ª 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog.2016.06.018
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%), 2.0e2.4 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 (P¼.0001). 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. Key words: lower uterine segment, uterine rupture, vaginal birth after
cesarean delivery
perform an elective repeat cesarean delivery (ERC). ECR will reduce the risk of uterine rupture but can also be associated with risks of short-term maternal complications, such as hemorrhage, hysterectomy, thromboembolism, and neonatal complications that include respiratory distress syndrome.5-7 In addition, cesarean delivery is associated with a higher risk of longer term complications, such as placenta praevia and accreta in future pregnancies.8,9 Therefore, the selection of the good candidate who is at low risk for uterine rupture during TOLAC is crucial. Assessment of lower uterine segment (LUS) thickness by ultrasound imaging in the third trimester of pregnancy has been proposed to predict the risk of uterine rupture.10-14 A landmark study by Rozenberg et al13 showed that the risk of a defective scar at delivery (uterine scar dehiscence and uterine rupture) is related directly to the degree of thinning of the LUS. They reported a risk of
uterine scar defect at delivery of 16% of women when the LUS thickness was Q4 <2.5 mm compared with 0.7% when the thickness was 3.5 mm or more.13 More recently, a LUS thickness of <2.3 mm was identified as a significant risk factor for uterine rupture.14 Although metaanalyses report no LUS thickness cutoff that can predict all uterine ruptures, most authors agree that the risk is high when the LUS thickness is <2.0 mm.10,11 We aimed to evaluate the occurrence of uterine rupture when LUS thickness measurement was included in the decision about delivery route in a large cohort of women who wanted to attempt TOLAC.
Materials and Methods Study design and participants We conducted a prospective cohort study between April 2009 and June 2013 in 3 Canadian Hospitals (Centre Hospitalier Universitaire de Québec, Québec; Centre Hospitalier Universitaire
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Sainte-Justine, Montreal; Centre Hospitalier Universitaire Fleurimont, Sherbrooke) and a Swiss Hospital (Hôpitaux Universitaires de Genève, Geneva). We recruited women who were contemplating a TOLAC with a single previous low-transverse cesarean delivery and a singleton pregnancy in cephalic presentation. The likelihood of VBAC and the risk of uterine rupture were evaluated and discussed between 34 weeks 0 days and 38 weeks 6 days of gestation.
Procedures After informed consent was obtained from the participant, a research nurse or midwife recorded maternal characteristics and medical and reproductive history, including the features of the previous cesarean delivery. Body mass index was calculated with the use of the maternal weight at inclusion (end of pregnancy). Tobacco use was considered when the woman was currently smoking. Diabetes mellitus included gestational and pregestational diabetes mellitus. Previous cesarean delivery that was performed for labor dystocia, cephalopelvic disproportion, descent arrest, or failure to progress was reported as previous cesarean delivery for recurrent reason. Examination of the LUS was performed with transabdominal and transvaginal ultrasound imaging with Voluson Expert or Voluson E8 (GE
Healthcare, Milwaukee, WI) between 34 weeks 0 days and 38 weeks 6 days of gestation by a trained sonographer or midwife who was supervised by a maternal-fetal medicine specialist in each center. At least 6 measurements (3 transabdominal and 3 transvaginal) of the LUS thickness were performed, with the use of the method previously described (Figure).14 The thinnest LUS value was retained. Fetal biometry (head circumference, biparietal diameter, abdominal circumference, femur length) was measured to estimate fetal weight with the use of the Hadlock formula.15 According to LUS thickness, women were classified in 3 risk categories for uterine rupture during TOLAC: high risk (<2.0 mm), intermediate risk (2.0e2.4 mm), and low risk (2.5 mm). Participants and their health care providers were informed of the risk category. All participants met with the obstetrician after the LUS assessment. During this consultation, each woman was informed about her risk of uterine rupture during TOLAC according to LUS thickness (average of 0.5e1%, most likely >1% when LUS is <2.0 mm and most likely <0.5% when LUS thickness is 2.5 mm); the consequences of uterine rupture (including perinatal asphyxia and death), the maternal and neonatal complications of ECR, and the chances of successful VBAC based on the indication of previous cesarean
FIGURE
Lower uterine segment thickness web 4C=FPO
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Lower uterine segment thickness measured by a A, transabdominal and a B, transvaginal scan. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016.
167 delivery (recurrent or not), previous 168 vaginal birth, and estimated fetal weight. 169 Finally, women were informed that 170 mode of delivery would be discussed 171 again in case of induction of labor or in 172 case of labor dystocia. The institutional 173 ethics committee in each center 174 approved the study. Medical records 175 were reviewed for obstetric and neonatal 176 outcomes after delivery. ½F1 177 Our primary outcome was symptom178 atic uterine rupture, defined as a com179 plete separation of the uterine scar that 180 resulted in protrusion of fetal or placental 181 parts in the peritoneal cavity and required 182 urgent laparotomy. Secondary outcomes 183 included incidental scar disruption 184 (complete opening of the previous scar 185 without protrusion of fetal or placental 186 parts in the peritoneal cavity) and uterine 187 scar dehiscence (defined as a small win188 dow in the LUS) that was diagnosed 189 during cesarean delivery. A routine 190 manual revision of the LUS integrity was 191 not performed after vaginal birth. 192 Other secondary outcomes included 193 the rates of TOLAC and VBAC, maternal 194 outcomes (postpartum hysterectomy, 195 blood transfusion, and maternal death), 196 neonatal outcomes (5-minute Apgar 197 score <7, cord blood pH <7.0, perinatal 198 asphyxia [defined as a 5-minute Apgar 199 score <4, a cord blood pH <7.0 when 200 available], and evidence of altered 201 neurologic status, and/or multisystem 202 organ failure), and intrapartum or 203 neonatal death. 204 205 Statistical analysis 206 Labor and delivery characteristics and 207 uterine scar defects were reported 208 according to LUS thickness categories 209 (<2.0 mm, 2.0e2.4 mm, and 2.5 210 mm). Neonatal and maternal outcomes 211 were stratified according to intended 212 mode of delivery. We estimated that the 213 use of the LUS thickness could result in a 214 low risk of uterine rupture in women 215 who undergo TOLAC. We calculated 216 that a minimum of 942 women who 217 underwent a TOLAC should be included 218 to exclude the value of 0.8% from our 219 estimate of the risk of uterine rupture 220 (1-sided test; a¼.05; power¼0.80) 221 should the observed risk be 0.2%. We 222 estimated that a minimum of 1450
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223 women who were contemplating VBAC recruitment (CHUQ) were more likely women who underwent repeat cesarean Q5 224 would need to be recruited to have at to have a LUS <2 mm (13% vs 5%, 6% delivery during labor, uterine scar de225 least 942 (65%) women who would and 9%, respectively; P<.001) or fects of any type (incidental scar 226 choose to attempt TOLAC. Statistical 2.0e2.4 mm (15% vs 7%, 5% and 9%, disruption or uterine scar dehiscence) 227 were observed more frequently in analyses were performed with SPSS respectively; P<.001). 228 women with a LUS of 2.0e2.4 mm. software (version 22.0; SPSS Inc, ChiLabor characteristics and delivery 229 We found a statistically significant ½T2 cago, IL). We calculated the confidence outcomes are reported in Table 2 . LUS 230 association between LUS thickness interval for proportions using the Fisher thickness measurement had a significant 231 and uterine scar dehiscence that was exact method and tested the statistical impact on the choice of intended mode 232 observed at repeat cesarean delivery in significance of the observed proportion of delivery; women with a thin LUS were 233 women who underwent ERC. All cases of compared with 0.8% using the method more likely to undergo ERC. We did not 234 uterine scar dehiscence at ERC were of the normal approximation of the observe any case of symptomatic uterine 235 observed in women with LUS <3.0 mm. binomial distribution. rupture in the entire cohort (0%; 95% 236 Adverse maternal and neonatal outconfidence interval, 0.0e0.4%). No case 237 comes are reported according to the of 984 TOLACs was significantly <0.8%, Results 238 intended mode of delivery (Table 3). ½T3 which was the expected risk (P¼.0001). We recruited 1856 women, of whom 239 Three cases of incidental scar disruption >99% (n¼1849) had complete followOne woman experienced unexplained 240 up data. Participant’s characteristics are without adverse perinatal outcomes intrauterine fetal death before labor at 241 were reported in 3 women who under- 37 weeks of gestation. She underwent ½T1 described in Table 1. LUS thickness was 242 went repeat cesarean delivery for labor TOLAC and had an uncomplicated <2.0 mm in 194 women (11%), at 243 dystocia after TOLAC. All 3 women had vaginal birth. Another woman had a 2.0e2.4 mm in 217 women (18%), and 244 no progression of cervical dilation or no fetus with hydrops; she underwent an 2.5 mm in 1445 women (78%). All 7 245 progression of fetal descent for >2 hours emergency cesarean delivery, and the women who were lost to follow up had 246 before the cesarean delivery was per- neonate died soon after delivery. The a LUS thickness 2.5 mm and had 247 formed. Uterine scar dehiscence was only case of perinatal asphyxia that similar characteristics as the others. We 248 observed in 22 other women who un- occurred in a woman who underwent observed that women who were 249 derwent TOLAC. Looking specifically at emergency cesarean delivery for fetal recruited in the center with most 250 251 252 TABLE 1 253 Characteristics of participants at recruitment 254 255 Patients characteristics All (n¼1856) <2.0 mm (n¼194) 2.0-2.4 mm (n¼217) 2.5 mm (n¼1445) 256 a 31.5 4.3 31.6 4.4 31.3 3.7 31.6 4.4 Maternal age, y 257 2a Body mass index, kg/m 29.2 5.2 27.7 4.1 28.6 4.9 29.5 5.3 258 259 Tobacco use, n (%) 149 (8) 12 (6) 26 (12) 111 (8) 260 Diabetes mellitus (pregestational 144 (8) 11 (6) 16 (7) 117 (8) 261 or gestational), n (%) 262 Previous vaginal delivery, n (%) 305 (16) 16 (8) 46 (21) 243 (17) 263 a Interdelivery interval, mo 44.1 31.3 39.7 24.3 46.7 33.8 44.3 31.7 264 265 Previous cesarean delivery for 766 (41) 39 (20) 57 (26) 670 (46) recurrent reason, n (%) 266 267 Gestational age at sonography, wka 36.6 1.7 36.7 0.8 36.8 0.8 36.6 1.9 268 a Estimated fetal weight, g 2999 396 2920 355 2997 375 3010 403 269 a Lower uterine segment thickness, mm 3.3 1.3 1.6 0.3 2.2 0.2 3.7 1.1 270 Centers, n (%) 271 Q6 272 Centre Hospitalier Universitaire (Quebec) 1081 (58) 139 (72) 164 (76) 778 (54) 273 Ste-Justine Hospital (Montreal) 340 (18) 16 (8) 16 (7) 308 (21) 274 Centre Hospitalier Universitaire (Sherbrooke) 63 (3) 4 (2) 3 (1) 56 (4) 275 Hoˆpitaux Universitaires de Gene`ve (Geneva) 372 (20) 35 (18) 34 (16) 303 (21) 276 a 277 Data are given as mean standard deviation. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016. 278 MONTH 2016 American Journal of Obstetrics & Gynecology FLA 5.4.0 DTD YMOB11155_proof 2 July 2016 2:46 pm ce
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TABLE 2
Labor characteristics and outcomes according to the lower uterine segment thickness categories Lower uterine segment thickness <2.0 mm (n¼194)
Variable
38.9 0.9
Gestational age at delivery, wka
2.0e2.4 mm (n¼217) 39.3 1.0
2.5 mm (n¼1438) 39.6 1.0
P value <0.0001
177 (91)
123 (57)
557 (39)
<.0001
Uterine scar dehiscence, n (%)
22 (12)
3 (2)
5 (1)
<.0001
Trial of labor, n (%)
17 (9)
Elective repeat cesarean delivery, n (%)
94 (43)
881 (61)
<.0001
Induction of labor
2 (12)
11 (12)
153 (17)
.32
Oxytocin during labor
6 (35)
32 (35)
363 (41)
.37
14 (82)
73 (78)
585 (66)
.04
Vaginal birth Symptomatic uterine rupture
0
0
0
Incidental scar disruption
0
0
3 (0.3)
— .83
Uterine scar dehiscence
0
5 (5.3)
17 (1.9)
.09
Any type of scar defect at cesarean delivery during labor
0/3
5/21 (24)
20/276 (7)
.02
Data are given as mean standard deviation. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016.
a
distress that was not related to a uterine scar defect. We observed no case of maternal death or postpartum hysterectomy, but 23 women (1.2%) received blood transfusion for postpartum hemorrhage that was more frequent in women who underwent a TOLAC.
Comment Our study suggests that integrating LUS thickness measurement in the
decision-making process on the route of delivery results in a low risk of uterine rupture during TOLAC and definitively influences the women’s choice about the route of delivery. Meta-analyses of numerous small studies showed an association between LUS thickness and the risk of uterine scar defect at delivery.10,11 Rozenberg et al16 observed no case of uterine rupture and only 2 uterine scar defects from the
TABLE 3
Neonatal and maternal outcomes according to intended mode of delivery Variable
Trial of labor (n¼984), n (%)
Elective repeat cesarean delivery (n¼865), n (%)
13 (1.3)
10 (1.2)
2 (<1)
2 (<1)
Neonatal outcomes Five-minute Apgar score <7 Arterial cord pH <7.0 Perinatal asphyxia
a
Intrapartum or neonatal death
1 (<1)
0
0
1 (<1)
Maternal outcome Maternal blood transfusion
17 (1.7)
6 (0.7)b
Postpartum hysterectomy
0
0
Maternal death
0
0
Defined as the combination of Apgar score at 5 minutes <4, arterial cord blood pH <7.0, and neonatal multisystemic organ failure; b P<.05. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016. a
170 women who underwent a TOLAC when the LUS thickness was integrated in the decision on the route of delivery. They observed that the introduction of LUS thickness measurement in clinical practice led to a significant reduction of emergency cesarean deliveries and uterine scar defects, when compared with the previous period. However, some differences between the 2 studies have to be pointed out. First, the former study used only abdominal ultrasound imaging; we used a combination of transabdominal and transvaginal ultrasound imaging.17,18 Second, based on previous literature,14 by suggesting safety, we used lower thresholds (2.0e2.5 mm instead of 3.5 mm). Our study confirmed the association between uterine scar dehiscence that was diagnosed at ERC and LUS thickness that was reported in published metaanalyses.10,11 In contrast, LUS thickness was not associated with uterine scar dehiscence that was diagnosed at repeat cesarean delivery after a failed TOLAC. This can be explained by the fact that the duration of labor and labor dystocia are major risk factors for uterine scar dehiscence.19-21 The 3 cases of incidental scar disruption that were observed in our cohort occurred in women with
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prolonged labor dystocia. This observation highlights the importance of the monitoring of labor progression in women with previous cesarean delivery. We observed only few cases of major maternal or perinatal morbidities or death that was related to uterine scar defect among almost 1000 TOLACs. We did not have the power to detect a significant reduction in perinatal asphyxia or hypoxic-ischemic encephalopathy that has been reported in approximately 5e10% of uterine rupture or approximately 0.1% of TOLAC.3 Similarly, postpartum hysterectomy was reported in 5e20% of uterine rupture or in approximately 0.2e0.3% of ERCs.3,22 We believe that the low risk of uterine rupture that was observed in our study is likely to translate to a reduced risk of all the major morbidities that are related to uterine rupture. The current study has some limitations that must be considered. It is likely that women who are informed about their greater risk of uterine rupture (because of thin LUS) were less likely to undergo a TOLAC, unless other favorable factors (previous vaginal delivery, rapid progression of cervical dilation) were present. Therefore, we cannot speculate about the association between LUS thickness and successful TOLAC and vaginal birth. Because the participants and their health care providers were informed about LUS thickness, it is also possible that a bias was introduced in the diagnosis of uterine scar dehiscence at ERC. However, the fact that all uterine scar dehiscence at ERC were observed in women with a LUS of <3.0 mm supports the strong inverse correlation between LUS thickness and the risk of scar disruption. We did not have a control group without LUS thickness measurement; therefore, it is difficult to estimate whether the low risk of uterine rupture is related to the LUS thickness measurement or to other interventions that could have occurred in our centers during the same period, which included changes in counselling. In conclusion, our study shows that the integration of LUS thickness in the decision about the route of delivery is associated with a low risk of uterine
rupture. This strategy has the potential to lead to an overall reduction of cesarean delivery in women with previous cesarean delivery by reassuring both women and clinicians about the relative safety of TOLAC. n Acknowledgments We thank the members of the Department of Obstetrics & Gynecology of Sainte-Justine Hospital, Montreal, QC, Canada; the Department of Obstetrics & Gynecology and the Department of Family Medicine of the Centre Hospitalier Universitaire de Québec, Québec, QC, Canada; the Department of Obstetrics & Gynecology of the CHU Fleurimont, Sherbrooke, QC, Canada; and the Department of Obstetrics and Gynecology of the Hôpitaux Universitaires de Genève (HUG), Geneva, Switzerland, for the recruitment of women in this study.
References 1. Hamilton BE, Martin JA, Ventura SJ. Births: preliminary data for 2012. Natl Vital Stat Rep 2013;62:1-20. 2. Guise JM, McDonagh MS, Osterweil P, Nygren P, Chan BK, Helfand M. Systematic review of the incidence and consequences of uterine rupture in women with previous caesarean section. BMJ 2004;329:19-25. 3. Landon MB, Hauth JC, Leveno KJ, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med 2004;351:2581-9. 4. Bujold E, Gauthier RJ, Hamilton E. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. J Midwifery Womens Health 2005;50:363-4. 5. Rageth JC, Juzi C, Grossenbacher H. Delivery after previous cesarean: a risk evaluation: Swiss Working Group of Obstetric and Gynecologic Institutions. Obstet Gynecol 1999;93: 332-7. 6. Steer PJ, Modi N. Elective caesarean sections: risks to the infant. Lancet 2009;374: 675-6. 7. Hook B, Kiwi R, Amini SB, Fanaroff A, Hack M. Neonatal morbidity after elective repeat cesarean section and trial of labor. Pediatrics 1997;100:348-53. 8. Pare E, Quinones JN, Macones GA. Vaginal birth after caesarean section versus elective repeat caesarean section: assessment of maternal downstream health outcomes. BJOG 2006;113:75-85. 9. Ananth CV, Smulian JC, Vintzileos AM. The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis. Am J Obstet Gynecol 1997;177:1071-8. 10. Kok N, Wiersma IC, Opmeer BC, de Graaf IM, Mol BW, Pajkrt E. Sonographic measurement of the lower uterine segment thickness to predict uterine rupture during a trial of labor in women with a previous cesarean section: a
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meta-analysis. Ultrasound Obstet Gynecol 2013;42:132-9. 11. Jastrow N, Chaillet N, Roberge S, Morency AM, Lacasse Y, Bujold E. Sonographic lower uterine segment thickness and risk of uterine scar defect: a systematic review. J Obstet Gynaecol Can 2010;32:321-7. 12. Fukuda M, Fukuda K, Mochizuki M. Examination of previous caesarean section scars by ultrasound. Arch Gynecol Obstet 1988;243: 221-4. 13. Rozenberg P, Goffinet F, Phillippe HJ, Nisand I. Ultrasonographic measurement of lower uterine segment to assess risk of defects of scarred uterus. Lancet 1996;347:281-4. 14. Bujold E, Jastrow N, Simoneau J, Brunet S, Gauthier RJ. Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment. Am J Obstet Gynecol 2009;201:320.e1-6. 15. Hadlock FP, Harrist RB, Sharman RS, Deter RL, Park SK. Estimation of fetal weight with the use of head, body, and femur measurements: a prospective study. Am J Obstet Gynecol 1985;151:333-7. 16. Rozenberg P, Goffinet F, Philippe HJ, Nisand I. Thickness of the lower uterine segment: its influence in the management of patients with previous cesarean sections. Eur J Obstet Gynecol Reprod Biol 1999;87: 39-45. 17. Laflamme SM, Jastrow N, Girard M, Paris G, Berube L, Bujold E. Pitfall in ultrasound evaluation of uterine scar from prior preterm cesarean section. AJP Rep 2011;1:65-8. 18. Boutin A, Berube L, Girard M, Bujold E. Labour before a caesarean section and the morphology of the lower uterine segment in the next pregnancy. J Obstet Gynaecol Can 2011;33:105. 19. Hamilton EF, Bujold E, McNamara H, Gauthier R, Platt RW. Dystocia among women with symptomatic uterine rupture. Am J Obstet Gynecol 2001;184:620-4. 20. Khan KS, Rizvi A. The partograph in the management of labor following cesarean section. Int J Gynaecol Obstet 1995;50:151-7. 21. Bergeron ME, Jastrow N, Brassard N, Paris G, Bujold E. Sonography of lower uterine segment thickness and prediction of uterine rupture. Obstet Gynecol 2009;113:520-2. 22. McMahon MJ, Luther ER, Bowes WA Jr, Olshan AF. Comparison of a trial of labor with an elective second cesarean section. N Engl J Med 1996;335:689-95.
Author and article information From the Department of Obstetrics & Gynaecology, Faculty of Medicine, Hoˆpitaux Universitaires de Gene`ve, Q2 Universite´ de Gene`ve, Switzerland (Drs Jastrow, Irion, and Boulvain); the Department of Obstetrics & Gynaecology, Faculty of Medicine, Centre de recherche du Centre hospitalier universitaire de Que´bec (Drs Demers, VachonMarceau, Brassard, and Bujold and Mr Girard), and the Department of Social and Preventive Medicine, Faculty of Medicine (Drs Abdous, Marcoux, and Bujold), Universite´
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Laval, Que´bec, QC, Canada; the Department of Obstetrics & Gynaecology, Faculty of Medicine, Hoˆpital SainteJustine, Universite´ de Montre´al, Montre´al, QC, Canada (Drs Chaillet and Gauthier); and the Department of Obstetrics & Gynaecology, Faculty of Medicine, Universite´ de Sherbrooke, Sherbrooke, QC, Canada (Dr Pasquier).
Received March 14, 2016; revised May 3, 2016; accepted June 11, 2016. Supported by the Canadian Institutes of Health Research (operating grant #210974), the Geneva University Hospitals (PRD #09-II-28), and the Jeanne et Jean-Louis Levesque Perinatal Research Chair at
Universite´ Laval, Canada. S.D. and E.B. hold a Researcher’s salary award from the Fonds de la Recherche Q3 du Que´beceSante´. The authors report no conflict of interest. Corresponding author: Emmanuel Bujold, MD, MSc, FRCSC. [email protected]
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Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study Q7
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Nicole Jastrow, MD; Suzanne Demers, MD; Nils Chaillet, PhD; Mario Girard, ; Robert J. Gauthier, MD; Jean-Charles Pasquier, MD, PhD; Belkacem Abdous, PhD; Chantale Vachon-Marceau, MD; Sylvie Marcoux, MD, PhD; Olivier Irion, MD; Normand Brassard, MD; Michel Boulvain, MD, PhD; Emmanuel Bujold, MD, MSc
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 (less than 2.0 mm), intermediate risk (2.0e2.4 mm), and low risk (2.5 mm). Our primary outcome was symptomatic uterine
I
n the last 3 decades, the rate of cesarean deliveries has been rising continuously worldwide and has reached >30% in many countries. A major contributor to this trend is the concomitant decline in the percentage of trial of labor after cesarean delivery (TOLAC) and vaginal birth after cesarean delivery (VBAC).1 Fear of intrapartum uterine rupture, a rare (0.4e1.1%) but potentially catastrophic complication of TOLAC, represents the main reason for this trend.2 Uterine rupture can lead to perinatal asphyxia or death and severe maternal complications.3,4 The alternative for TOLAC is to
Cite this article as: Jastrow N, Demers S, Chaillet N, et al. Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study. Am J Obstet Gynecol 2016;:. 0002-9378/$36.00 ª 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog.2016.06.018
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%), 2.0e2.4 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 (P¼.0001). 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. Key words: lower uterine segment, uterine rupture, vaginal birth after
cesarean delivery
perform an elective repeat cesarean delivery (ERC). ECR will reduce the risk of uterine rupture but can also be associated with risks of short-term maternal complications, such as hemorrhage, hysterectomy, thromboembolism, and neonatal complications that include respiratory distress syndrome.5-7 In addition, cesarean delivery is associated with a higher risk of longer term complications, such as placenta praevia and accreta in future pregnancies.8,9 Therefore, the selection of the good candidate who is at low risk for uterine rupture during TOLAC is crucial. Assessment of lower uterine segment (LUS) thickness by ultrasound imaging in the third trimester of pregnancy has been proposed to predict the risk of uterine rupture.10-14 A landmark study by Rozenberg et al13 showed that the risk of a defective scar at delivery (uterine scar dehiscence and uterine rupture) is related directly to the degree of thinning of the LUS. They reported a risk of
uterine scar defect at delivery of 16% of women when the LUS thickness was Q4 <2.5 mm compared with 0.7% when the thickness was 3.5 mm or more.13 More recently, a LUS thickness of <2.3 mm was identified as a significant risk factor for uterine rupture.14 Although metaanalyses report no LUS thickness cutoff that can predict all uterine ruptures, most authors agree that the risk is high when the LUS thickness is <2.0 mm.10,11 We aimed to evaluate the occurrence of uterine rupture when LUS thickness measurement was included in the decision about delivery route in a large cohort of women who wanted to attempt TOLAC.
Materials and Methods Study design and participants We conducted a prospective cohort study between April 2009 and June 2013 in 3 Canadian Hospitals (Centre Hospitalier Universitaire de Québec, Québec; Centre Hospitalier Universitaire
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Sainte-Justine, Montreal; Centre Hospitalier Universitaire Fleurimont, Sherbrooke) and a Swiss Hospital (Hôpitaux Universitaires de Genève, Geneva). We recruited women who were contemplating a TOLAC with a single previous low-transverse cesarean delivery and a singleton pregnancy in cephalic presentation. The likelihood of VBAC and the risk of uterine rupture were evaluated and discussed between 34 weeks 0 days and 38 weeks 6 days of gestation.
Procedures After informed consent was obtained from the participant, a research nurse or midwife recorded maternal characteristics and medical and reproductive history, including the features of the previous cesarean delivery. Body mass index was calculated with the use of the maternal weight at inclusion (end of pregnancy). Tobacco use was considered when the woman was currently smoking. Diabetes mellitus included gestational and pregestational diabetes mellitus. Previous cesarean delivery that was performed for labor dystocia, cephalopelvic disproportion, descent arrest, or failure to progress was reported as previous cesarean delivery for recurrent reason. Examination of the LUS was performed with transabdominal and transvaginal ultrasound imaging with Voluson Expert or Voluson E8 (GE
Healthcare, Milwaukee, WI) between 34 weeks 0 days and 38 weeks 6 days of gestation by a trained sonographer or midwife who was supervised by a maternal-fetal medicine specialist in each center. At least 6 measurements (3 transabdominal and 3 transvaginal) of the LUS thickness were performed, with the use of the method previously described (Figure).14 The thinnest LUS value was retained. Fetal biometry (head circumference, biparietal diameter, abdominal circumference, femur length) was measured to estimate fetal weight with the use of the Hadlock formula.15 According to LUS thickness, women were classified in 3 risk categories for uterine rupture during TOLAC: high risk (<2.0 mm), intermediate risk (2.0e2.4 mm), and low risk (2.5 mm). Participants and their health care providers were informed of the risk category. All participants met with the obstetrician after the LUS assessment. During this consultation, each woman was informed about her risk of uterine rupture during TOLAC according to LUS thickness (average of 0.5e1%, most likely >1% when LUS is <2.0 mm and most likely <0.5% when LUS thickness is 2.5 mm); the consequences of uterine rupture (including perinatal asphyxia and death), the maternal and neonatal complications of ECR, and the chances of successful VBAC based on the indication of previous cesarean
FIGURE
Lower uterine segment thickness web 4C=FPO
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Lower uterine segment thickness measured by a A, transabdominal and a B, transvaginal scan. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016.
167 delivery (recurrent or not), previous 168 vaginal birth, and estimated fetal weight. 169 Finally, women were informed that 170 mode of delivery would be discussed 171 again in case of induction of labor or in 172 case of labor dystocia. The institutional 173 ethics committee in each center 174 approved the study. Medical records 175 were reviewed for obstetric and neonatal 176 outcomes after delivery. ½F1 177 Our primary outcome was symptom178 atic uterine rupture, defined as a com179 plete separation of the uterine scar that 180 resulted in protrusion of fetal or placental 181 parts in the peritoneal cavity and required 182 urgent laparotomy. Secondary outcomes 183 included incidental scar disruption 184 (complete opening of the previous scar 185 without protrusion of fetal or placental 186 parts in the peritoneal cavity) and uterine 187 scar dehiscence (defined as a small win188 dow in the LUS) that was diagnosed 189 during cesarean delivery. A routine 190 manual revision of the LUS integrity was 191 not performed after vaginal birth. 192 Other secondary outcomes included 193 the rates of TOLAC and VBAC, maternal 194 outcomes (postpartum hysterectomy, 195 blood transfusion, and maternal death), 196 neonatal outcomes (5-minute Apgar 197 score <7, cord blood pH <7.0, perinatal 198 asphyxia [defined as a 5-minute Apgar 199 score <4, a cord blood pH <7.0 when 200 available], and evidence of altered 201 neurologic status, and/or multisystem 202 organ failure), and intrapartum or 203 neonatal death. 204 205 Statistical analysis 206 Labor and delivery characteristics and 207 uterine scar defects were reported 208 according to LUS thickness categories 209 (<2.0 mm, 2.0e2.4 mm, and 2.5 210 mm). Neonatal and maternal outcomes 211 were stratified according to intended 212 mode of delivery. We estimated that the 213 use of the LUS thickness could result in a 214 low risk of uterine rupture in women 215 who undergo TOLAC. We calculated 216 that a minimum of 942 women who 217 underwent a TOLAC should be included 218 to exclude the value of 0.8% from our 219 estimate of the risk of uterine rupture 220 (1-sided test; a¼.05; power¼0.80) 221 should the observed risk be 0.2%. We 222 estimated that a minimum of 1450
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223 women who were contemplating VBAC recruitment (CHUQ) were more likely women who underwent repeat cesarean Q5 224 would need to be recruited to have at to have a LUS <2 mm (13% vs 5%, 6% delivery during labor, uterine scar de225 least 942 (65%) women who would and 9%, respectively; P<.001) or fects of any type (incidental scar 226 choose to attempt TOLAC. Statistical 2.0e2.4 mm (15% vs 7%, 5% and 9%, disruption or uterine scar dehiscence) 227 were observed more frequently in analyses were performed with SPSS respectively; P<.001). 228 women with a LUS of 2.0e2.4 mm. software (version 22.0; SPSS Inc, ChiLabor characteristics and delivery 229 We found a statistically significant ½T2 cago, IL). We calculated the confidence outcomes are reported in Table 2 . LUS 230 association between LUS thickness interval for proportions using the Fisher thickness measurement had a significant 231 and uterine scar dehiscence that was exact method and tested the statistical impact on the choice of intended mode 232 observed at repeat cesarean delivery in significance of the observed proportion of delivery; women with a thin LUS were 233 women who underwent ERC. All cases of compared with 0.8% using the method more likely to undergo ERC. We did not 234 uterine scar dehiscence at ERC were of the normal approximation of the observe any case of symptomatic uterine 235 observed in women with LUS <3.0 mm. binomial distribution. rupture in the entire cohort (0%; 95% 236 Adverse maternal and neonatal outconfidence interval, 0.0e0.4%). No case 237 comes are reported according to the of 984 TOLACs was significantly <0.8%, Results 238 intended mode of delivery (Table 3). ½T3 which was the expected risk (P¼.0001). We recruited 1856 women, of whom 239 Three cases of incidental scar disruption >99% (n¼1849) had complete followOne woman experienced unexplained 240 up data. Participant’s characteristics are without adverse perinatal outcomes intrauterine fetal death before labor at 241 were reported in 3 women who under- 37 weeks of gestation. She underwent ½T1 described in Table 1. LUS thickness was 242 went repeat cesarean delivery for labor TOLAC and had an uncomplicated <2.0 mm in 194 women (11%), at 243 dystocia after TOLAC. All 3 women had vaginal birth. Another woman had a 2.0e2.4 mm in 217 women (18%), and 244 no progression of cervical dilation or no fetus with hydrops; she underwent an 2.5 mm in 1445 women (78%). All 7 245 progression of fetal descent for >2 hours emergency cesarean delivery, and the women who were lost to follow up had 246 before the cesarean delivery was per- neonate died soon after delivery. The a LUS thickness 2.5 mm and had 247 formed. Uterine scar dehiscence was only case of perinatal asphyxia that similar characteristics as the others. We 248 observed in 22 other women who un- occurred in a woman who underwent observed that women who were 249 derwent TOLAC. Looking specifically at emergency cesarean delivery for fetal recruited in the center with most 250 251 252 TABLE 1 253 Characteristics of participants at recruitment 254 255 Patients characteristics All (n¼1856) <2.0 mm (n¼194) 2.0-2.4 mm (n¼217) 2.5 mm (n¼1445) 256 a 31.5 4.3 31.6 4.4 31.3 3.7 31.6 4.4 Maternal age, y 257 2a Body mass index, kg/m 29.2 5.2 27.7 4.1 28.6 4.9 29.5 5.3 258 259 Tobacco use, n (%) 149 (8) 12 (6) 26 (12) 111 (8) 260 Diabetes mellitus (pregestational 144 (8) 11 (6) 16 (7) 117 (8) 261 or gestational), n (%) 262 Previous vaginal delivery, n (%) 305 (16) 16 (8) 46 (21) 243 (17) 263 a Interdelivery interval, mo 44.1 31.3 39.7 24.3 46.7 33.8 44.3 31.7 264 265 Previous cesarean delivery for 766 (41) 39 (20) 57 (26) 670 (46) recurrent reason, n (%) 266 267 Gestational age at sonography, wka 36.6 1.7 36.7 0.8 36.8 0.8 36.6 1.9 268 a Estimated fetal weight, g 2999 396 2920 355 2997 375 3010 403 269 a Lower uterine segment thickness, mm 3.3 1.3 1.6 0.3 2.2 0.2 3.7 1.1 270 Centers, n (%) 271 Q6 272 Centre Hospitalier Universitaire (Quebec) 1081 (58) 139 (72) 164 (76) 778 (54) 273 Ste-Justine Hospital (Montreal) 340 (18) 16 (8) 16 (7) 308 (21) 274 Centre Hospitalier Universitaire (Sherbrooke) 63 (3) 4 (2) 3 (1) 56 (4) 275 Hoˆpitaux Universitaires de Gene`ve (Geneva) 372 (20) 35 (18) 34 (16) 303 (21) 276 a 277 Data are given as mean standard deviation. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016. 278 MONTH 2016 American Journal of Obstetrics & Gynecology FLA 5.4.0 DTD YMOB11155_proof 2 July 2016 2:46 pm ce
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TABLE 2
Labor characteristics and outcomes according to the lower uterine segment thickness categories Lower uterine segment thickness <2.0 mm (n¼194)
Variable
38.9 0.9
Gestational age at delivery, wka
2.0e2.4 mm (n¼217) 39.3 1.0
2.5 mm (n¼1438) 39.6 1.0
P value <0.0001
177 (91)
123 (57)
557 (39)
<.0001
Uterine scar dehiscence, n (%)
22 (12)
3 (2)
5 (1)
<.0001
Trial of labor, n (%)
17 (9)
Elective repeat cesarean delivery, n (%)
94 (43)
881 (61)
<.0001
Induction of labor
2 (12)
11 (12)
153 (17)
.32
Oxytocin during labor
6 (35)
32 (35)
363 (41)
.37
14 (82)
73 (78)
585 (66)
.04
Vaginal birth Symptomatic uterine rupture
0
0
0
Incidental scar disruption
0
0
3 (0.3)
— .83
Uterine scar dehiscence
0
5 (5.3)
17 (1.9)
.09
Any type of scar defect at cesarean delivery during labor
0/3
5/21 (24)
20/276 (7)
.02
Data are given as mean standard deviation. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016.
a
distress that was not related to a uterine scar defect. We observed no case of maternal death or postpartum hysterectomy, but 23 women (1.2%) received blood transfusion for postpartum hemorrhage that was more frequent in women who underwent a TOLAC.
Comment Our study suggests that integrating LUS thickness measurement in the
decision-making process on the route of delivery results in a low risk of uterine rupture during TOLAC and definitively influences the women’s choice about the route of delivery. Meta-analyses of numerous small studies showed an association between LUS thickness and the risk of uterine scar defect at delivery.10,11 Rozenberg et al16 observed no case of uterine rupture and only 2 uterine scar defects from the
TABLE 3
Neonatal and maternal outcomes according to intended mode of delivery Variable
Trial of labor (n¼984), n (%)
Elective repeat cesarean delivery (n¼865), n (%)
13 (1.3)
10 (1.2)
2 (<1)
2 (<1)
Neonatal outcomes Five-minute Apgar score <7 Arterial cord pH <7.0 Perinatal asphyxia
a
Intrapartum or neonatal death
1 (<1)
0
0
1 (<1)
Maternal outcome Maternal blood transfusion
17 (1.7)
6 (0.7)b
Postpartum hysterectomy
0
0
Maternal death
0
0
Defined as the combination of Apgar score at 5 minutes <4, arterial cord blood pH <7.0, and neonatal multisystemic organ failure; b P<.05. Jastrow et al. Lower uterine segment thickness and uterine rupture. Am J Obstet Gynecol 2016. a
170 women who underwent a TOLAC when the LUS thickness was integrated in the decision on the route of delivery. They observed that the introduction of LUS thickness measurement in clinical practice led to a significant reduction of emergency cesarean deliveries and uterine scar defects, when compared with the previous period. However, some differences between the 2 studies have to be pointed out. First, the former study used only abdominal ultrasound imaging; we used a combination of transabdominal and transvaginal ultrasound imaging.17,18 Second, based on previous literature,14 by suggesting safety, we used lower thresholds (2.0e2.5 mm instead of 3.5 mm). Our study confirmed the association between uterine scar dehiscence that was diagnosed at ERC and LUS thickness that was reported in published metaanalyses.10,11 In contrast, LUS thickness was not associated with uterine scar dehiscence that was diagnosed at repeat cesarean delivery after a failed TOLAC. This can be explained by the fact that the duration of labor and labor dystocia are major risk factors for uterine scar dehiscence.19-21 The 3 cases of incidental scar disruption that were observed in our cohort occurred in women with
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prolonged labor dystocia. This observation highlights the importance of the monitoring of labor progression in women with previous cesarean delivery. We observed only few cases of major maternal or perinatal morbidities or death that was related to uterine scar defect among almost 1000 TOLACs. We did not have the power to detect a significant reduction in perinatal asphyxia or hypoxic-ischemic encephalopathy that has been reported in approximately 5e10% of uterine rupture or approximately 0.1% of TOLAC.3 Similarly, postpartum hysterectomy was reported in 5e20% of uterine rupture or in approximately 0.2e0.3% of ERCs.3,22 We believe that the low risk of uterine rupture that was observed in our study is likely to translate to a reduced risk of all the major morbidities that are related to uterine rupture. The current study has some limitations that must be considered. It is likely that women who are informed about their greater risk of uterine rupture (because of thin LUS) were less likely to undergo a TOLAC, unless other favorable factors (previous vaginal delivery, rapid progression of cervical dilation) were present. Therefore, we cannot speculate about the association between LUS thickness and successful TOLAC and vaginal birth. Because the participants and their health care providers were informed about LUS thickness, it is also possible that a bias was introduced in the diagnosis of uterine scar dehiscence at ERC. However, the fact that all uterine scar dehiscence at ERC were observed in women with a LUS of <3.0 mm supports the strong inverse correlation between LUS thickness and the risk of scar disruption. We did not have a control group without LUS thickness measurement; therefore, it is difficult to estimate whether the low risk of uterine rupture is related to the LUS thickness measurement or to other interventions that could have occurred in our centers during the same period, which included changes in counselling. In conclusion, our study shows that the integration of LUS thickness in the decision about the route of delivery is associated with a low risk of uterine
rupture. This strategy has the potential to lead to an overall reduction of cesarean delivery in women with previous cesarean delivery by reassuring both women and clinicians about the relative safety of TOLAC. n Acknowledgments We thank the members of the Department of Obstetrics & Gynecology of Sainte-Justine Hospital, Montreal, QC, Canada; the Department of Obstetrics & Gynecology and the Department of Family Medicine of the Centre Hospitalier Universitaire de Québec, Québec, QC, Canada; the Department of Obstetrics & Gynecology of the CHU Fleurimont, Sherbrooke, QC, Canada; and the Department of Obstetrics and Gynecology of the Hôpitaux Universitaires de Genève (HUG), Geneva, Switzerland, for the recruitment of women in this study.
References 1. Hamilton BE, Martin JA, Ventura SJ. Births: preliminary data for 2012. Natl Vital Stat Rep 2013;62:1-20. 2. Guise JM, McDonagh MS, Osterweil P, Nygren P, Chan BK, Helfand M. Systematic review of the incidence and consequences of uterine rupture in women with previous caesarean section. BMJ 2004;329:19-25. 3. Landon MB, Hauth JC, Leveno KJ, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med 2004;351:2581-9. 4. Bujold E, Gauthier RJ, Hamilton E. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. J Midwifery Womens Health 2005;50:363-4. 5. Rageth JC, Juzi C, Grossenbacher H. Delivery after previous cesarean: a risk evaluation: Swiss Working Group of Obstetric and Gynecologic Institutions. Obstet Gynecol 1999;93: 332-7. 6. Steer PJ, Modi N. Elective caesarean sections: risks to the infant. Lancet 2009;374: 675-6. 7. Hook B, Kiwi R, Amini SB, Fanaroff A, Hack M. Neonatal morbidity after elective repeat cesarean section and trial of labor. Pediatrics 1997;100:348-53. 8. Pare E, Quinones JN, Macones GA. Vaginal birth after caesarean section versus elective repeat caesarean section: assessment of maternal downstream health outcomes. BJOG 2006;113:75-85. 9. Ananth CV, Smulian JC, Vintzileos AM. The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis. Am J Obstet Gynecol 1997;177:1071-8. 10. Kok N, Wiersma IC, Opmeer BC, de Graaf IM, Mol BW, Pajkrt E. Sonographic measurement of the lower uterine segment thickness to predict uterine rupture during a trial of labor in women with a previous cesarean section: a
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meta-analysis. Ultrasound Obstet Gynecol 2013;42:132-9. 11. Jastrow N, Chaillet N, Roberge S, Morency AM, Lacasse Y, Bujold E. Sonographic lower uterine segment thickness and risk of uterine scar defect: a systematic review. J Obstet Gynaecol Can 2010;32:321-7. 12. Fukuda M, Fukuda K, Mochizuki M. Examination of previous caesarean section scars by ultrasound. Arch Gynecol Obstet 1988;243: 221-4. 13. Rozenberg P, Goffinet F, Phillippe HJ, Nisand I. Ultrasonographic measurement of lower uterine segment to assess risk of defects of scarred uterus. Lancet 1996;347:281-4. 14. Bujold E, Jastrow N, Simoneau J, Brunet S, Gauthier RJ. Prediction of complete uterine rupture by sonographic evaluation of the lower uterine segment. Am J Obstet Gynecol 2009;201:320.e1-6. 15. Hadlock FP, Harrist RB, Sharman RS, Deter RL, Park SK. Estimation of fetal weight with the use of head, body, and femur measurements: a prospective study. Am J Obstet Gynecol 1985;151:333-7. 16. Rozenberg P, Goffinet F, Philippe HJ, Nisand I. Thickness of the lower uterine segment: its influence in the management of patients with previous cesarean sections. Eur J Obstet Gynecol Reprod Biol 1999;87: 39-45. 17. Laflamme SM, Jastrow N, Girard M, Paris G, Berube L, Bujold E. Pitfall in ultrasound evaluation of uterine scar from prior preterm cesarean section. AJP Rep 2011;1:65-8. 18. Boutin A, Berube L, Girard M, Bujold E. Labour before a caesarean section and the morphology of the lower uterine segment in the next pregnancy. J Obstet Gynaecol Can 2011;33:105. 19. Hamilton EF, Bujold E, McNamara H, Gauthier R, Platt RW. Dystocia among women with symptomatic uterine rupture. Am J Obstet Gynecol 2001;184:620-4. 20. Khan KS, Rizvi A. The partograph in the management of labor following cesarean section. Int J Gynaecol Obstet 1995;50:151-7. 21. Bergeron ME, Jastrow N, Brassard N, Paris G, Bujold E. Sonography of lower uterine segment thickness and prediction of uterine rupture. Obstet Gynecol 2009;113:520-2. 22. McMahon MJ, Luther ER, Bowes WA Jr, Olshan AF. Comparison of a trial of labor with an elective second cesarean section. N Engl J Med 1996;335:689-95.
Author and article information From the Department of Obstetrics & Gynaecology, Faculty of Medicine, Hoˆpitaux Universitaires de Gene`ve, Q2 Universite´ de Gene`ve, Switzerland (Drs Jastrow, Irion, and Boulvain); the Department of Obstetrics & Gynaecology, Faculty of Medicine, Centre de recherche du Centre hospitalier universitaire de Que´bec (Drs Demers, VachonMarceau, Brassard, and Bujold and Mr Girard), and the Department of Social and Preventive Medicine, Faculty of Medicine (Drs Abdous, Marcoux, and Bujold), Universite´
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Laval, Que´bec, QC, Canada; the Department of Obstetrics & Gynaecology, Faculty of Medicine, Hoˆpital SainteJustine, Universite´ de Montre´al, Montre´al, QC, Canada (Drs Chaillet and Gauthier); and the Department of Obstetrics & Gynaecology, Faculty of Medicine, Universite´ de Sherbrooke, Sherbrooke, QC, Canada (Dr Pasquier).
Received March 14, 2016; revised May 3, 2016; accepted June 11, 2016. Supported by the Canadian Institutes of Health Research (operating grant #210974), the Geneva University Hospitals (PRD #09-II-28), and the Jeanne et Jean-Louis Levesque Perinatal Research Chair at
Universite´ Laval, Canada. S.D. and E.B. hold a Researcher’s salary award from the Fonds de la Recherche Q3 du Que´beceSante´. The authors report no conflict of interest. Corresponding author: Emmanuel Bujold, MD, MSc, FRCSC. [email protected]
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