IJG-07958; No of Pages 3 International Journal of Gynecology and Obstetrics xxx (2014) xxx–xxx
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International Journal of Gynecology and Obstetrics journal homepage: www.elsevier.com/locate/ijgo
CLINICAL ARTICLE
The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births☆ Joel Baron ⁎, Adi Y. Weintraub, Tamar Eshkoli, Reli Hershkovitz, Eyal Sheiner Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
a r t i c l e
i n f o
Article history: Received 20 July 2013 Received in revised form 15 February 2014 Accepted 17 April 2014 Keywords: Cesarean delivery Fetal complication Obstetric complication Risk factor Uterine rupture Uterine scar dehiscence
a b s t r a c t Objective: To determine whether women with a previous uterine scar dehiscence are at increased risk of adverse perinatal outcomes in the following delivery. Methods: A retrospective cohort study was conducted of all subsequent singleton cesarean deliveries performed at the Soroka University Medical Center, Beer-Sheva, Israel, between January 1, 1988, and December 31, 2011. Clinical and demographic characteristics, maternal obstetric complications, and fetal complications were evaluated among women with or without a previous documented uterine scar dehiscence. Results: Of the 5635 pregnancies associated with at least two previous cesarean deliveries, 180 (3.2%) occurred among women with a previous uterine scar dehiscence. Women with this condition in a prior pregnancy were more likely than those without previous uterine scar dehiscence to experience subsequent preterm delivery (86 [47.8%] vs 1350 [24.7%]; P b 0.001), low birth weight (47 [26.1%] vs 861 [15.8%]; P b 0.001), and peripartum hysterectomy (5 [2.8%] vs 20 [0.4%]; P b 0.001). Nevertheless, previous uterine scar dehiscence did not increase the risk of uterine rupture, placenta accreta, or adverse perinatal outcomes, such as low Apgar scores at 5 minutes and perinatal mortality. Conclusion: Uterine scar dehiscence in a previous pregnancy is a potential risk factor for preterm delivery, low birth weight, and peripartum hysterectomy in the following pregnancy. © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction The number of cesarean deliveries performed has increased worldwide over time. For example, the rate recorded in the USA has risen from 5.0% in 1970 to 32.9% in 2009 [1]. Dehiscence of the uterine scar is a known complication of cesarean delivery. Various definitions of this condition are found in the literature for example: "a subperitoneal separation of the uterine scar, with the chorioamniotic membrane visible through the peritoneum" [2] and "the absence of the myometrium or the presence of an extremely thin myometrium diagnosed at the time of cesarean delivery" [3]. Uterine scar dehiscence is observed among 0.2%–4.3% of all pregnancies associated with a previous history of cesarean delivery [4–8] and can potentially lead to uterine rupture. The consequences of uterine rupture during a trial of vaginal delivery after cesarean delivery have been widely discussed in the literature and are associated with serious complications endangering both the mother and her offspring [9,10].
A study conducted by Landon et al. [9] reported a 0.38% perinatal morbidity rate following uterine rupture at term; furthermore, the intrapartum death rate was 0.03% and the rate of hypoxic–ischemic encephalopathy was 0.08%. Valentin et al. [11] found that uterine rupture was associated with a short interval between deliveries, a birth weight of 4000 g or over, induction of labor, oxytocin dose, and a thin lower uterine segment at 35–40 weeks of pregnancy; by contrast, a low risk of uterine rupture was noted among women with a previous vaginal delivery. In other studies, reported independent risk factors for uterine rupture included previous cesarean delivery, preterm delivery, malpresentation, parity, and dystocia during the first and second stages of labor [12–14]. Data regarding the consequences and complications of a previous uterine scar dehiscence on the following pregnancy are scarce. The aim of the present study was to investigate the maternal and perinatal outcomes in pregnancies associated with previous cesarean delivery and uterine scar dehiscence. 2. Materials and methods
☆ Abstract presented at the Society for Maternal-Fetal Medicine Annual Meeting, February 11–16, 2013, San Francisco, USA. ⁎ Corresponding author at: Department of Obstetrics and Gynecology, Soroka University Medical Center, POB 151, Beer Sheva 84101, Israel. Tel.: + 972 8 6400423; fax: +972 8 6403854. E-mail address: [email protected] (J. Baron).
A retrospective cohort study was conducted that compared the pregnancy outcomes of women with and without a previous uterine scar dehiscence who underwent a subsequent singleton cesarean delivery at the Soroka University Medical Center, Beer-Sheva, Israel, between
http://dx.doi.org/10.1016/j.ijgo.2014.02.022 0020-7292/© 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
2
J. Baron et al. / International Journal of Gynecology and Obstetrics xxx (2014) xxx–xxx
January 1, 1998, and December 31, 2011. The Soroka University Medical Center ethics review board approved the present study; informed consent was not required owing to the retrospective design. The Soroka University Medical Center is the sole tertiary hospital in the Negev (the southern region of Israel) and it provides care for nearly all of the pregnancies that occur in this geographic area. Most women with one or more previous cesarean deliveries were evaluated in a pre-surgical clinic. The most recent surgical report was overviewed and an ultrasonographic examination performed if needed. The surgical team comprised highly skilled and experienced obstetricians, with at least one senior consultant present in the operating room during the procedure. All surgeons used the same uterine closure technique with double layer sutures. A computerized database was used to identify women who had previously undergone at least two cesarean deliveries at the Soroka University Medical Center. Patient information was recorded by the obstetrician immediately after delivery and reviewed by trained medical secretaries. Coding was performed after thorough evaluation of both prenatal medical care records and routine hospital documents. The outcomes of singleton pregnancies subsequent to at least two previous cesarean deliveries were examined to identify women either with or without a prior uterine scar dehiscence. A clinical diagnosis of uterine scar dehiscence was made in cases where a thin, transparent lower uterine segment was observed by the senior surgeon. Exclusion criteria included fewer than two cesarean deliveries and multiple gestations. Demographic and clinical characteristics included maternal age, ethnicity, gestational age, parity, neonatal sex, and birth weight. The pregnancy and labor complications and birth outcomes that were assessed in the present study included premature rupture of membranes, meconium-stained amniotic fluid, preterm delivery, placenta previa, placenta accreta, uterine rupture, peripartum hysterectomy, blood transfusion, low birth weight, low Apgar score at 5 minutes, and perinatal mortality. The data were analyzed using SPSS version 17.0 (SPSS Inc, Chicago, IL, USA). The χ2 test or Fisher exact test was used to evaluate the categorical variables, whereas the t test was used for the continuous variables. The Mantel-Haenszel procedure was used to obtain the odds ratio (OR). A P value below 0.05 was considered statistically significant. 3. Results During the study period, 5635 women had undergone at least two previous cesarean deliveries; of these, 180 women (3.2%) had a previous uterine scar dehiscence. The clinical and demographic characteristics of the present study cohort are presented in Table 1. The prevalence of uterine scar dehiscence was more frequent among women of Bedouin Arab ethnicity than those of Jewish ethnicity (P b 0.001).
Table 1 Clinical and demographic characteristics among women with and without uterine scar dehiscence during previous cesarean delivery.a Characteristic
Uterine scar dehiscence No uterine scar dehiscence P valueb (n = 180) (n = 5455)
Maternal age, y Ethnicity Bedouin Arab Jewish Parity 3–4 ≥5 Gestational age, wk Sex of neonate Female Male
32.0 ± 4.3
32.6 ± 4.9
133 (73.9) 47 (26.1)
3469 (63.6) 1986 (36.4)
b0.001
84 (46.7) 96 (53.3) 36.1 ± 2.0
2823 (51.8) 2632 (48.2) 37.0 ± 2.1
0.179
87 (48.3) 93 (51.7)
2675 (49.0) 2780 (51.0)
0.852
a
Complication
Uterine scar No uterine scar OR dehiscence dehiscence (n = 5455) (n = 180)
Polyhydramnion Breech presentation Premature rupture of membranes Meconium-stained amniotic fluid Severe pre-eclampsia toxemia Preterm delivery (b37 wk) Preterm delivery (b34 wk) Placenta accreta Placenta previa Placental abruption Postpartum hemorrhage Blood transfusion Anemia before delivery (Hb b10 mg/dL) Uterine rupture Peripartum hysterectomy
11 (6.1) 8 (4.4) 7 (3.9)
364 (6.7) 182 (3.3) 148 (2.7)
0.91 0.49–1.69 1.34 0.65–2.78 1.45 0.67–3.14
0.45 0.26 0.22
4 (2.2)
226 (4.1)
0.52 0.19–1.42
0.13
2 (1.1)
118 (2.2)
0.50 0.12–2.07
0.25
86 (47.8)
1350 (24.7)
2.78 2.06–3.75
b0.001
14 (7.8)
227 (4.2)
1.94 1.10–3.40
0.01
1 (0.6) 5 (2.8) 1 (0.6) 2 (1.1) 14 (7.8) 96 (53.3)
27 (0.5) 100 (1.8) 60 (1.1) 19 (0.3) 212 (3.9) 2661 (48.8)
1.12 1.53 0.50 3.21 2.08 1.20
0.59 0.24 0.41 0.14 0.01 0.13
2 (1.1) 5 (2.8)
23 (0.4) 20 (0.4)
0.001
95% CI
0.15–8.31 0.61–3.80 0.06–3.64 0.74–13.90 1.18–3.36 0.89–1.61
P value
2.65 0.62–11.34 0.19 7.74 2.88–20.92 b0.001
Abbreviations: CI, confidence interval; Hb, hemoglobin; OR, odds ratio. a Values are given as number (percentage). b The Mantel-Haenszel procedure was used to obtain the ORs. P b 0.05 was considered statistically significant.
The mean gestational age was 36.1 ± 2.0 weeks in the uterine scar dehiscence group versus 37.0 ± 2.1 weeks in the group without uterine scar dehiscence (P b 0.001). Obstetric complications of women with and without a previous uterine scar dehiscence are shown in Table 2. Previous uterine scar dehiscence was significantly associated with adverse pregnancy outcomes, including preterm delivery, peripartum hysterectomy, and the need for blood transfusion in the subsequent pregnancy. Neonates born following a pregnancy complicated by uterine scar dehiscence had significantly lower birth weight (b2500 g) than neonates whose mothers did not have this complication (Table 3). However, very low birth weight (b 1500 g), a 5-minute Apgar score below seven, and perinatal mortality did not differ between the two groups. 4. Discussion The aim of the present study was to investigate the influence of a previous uterine scar dehiscence on the obstetric and perinatal
Table 3 Fetal complications among women with and without uterine scar dehiscence during previous cesarean delivery.a,b Complication
Uterine scar dehiscence (n = 180)
No uterine scar dehiscence (n = 5455)
OR
95% CI
P value
Low birth weight (b2500 g) Very low birth weight (b1500 g) Low 5-minute Apgar score (b7) Perinatal mortality Prepartum death Postpartum death
47 (26.1)
861 (15.8)
1.88
1.34–2.65
b0.001
3 (1.7)
118 (2.2)
0.76
0.24–2.43
0.45
6 (3.3)
135 (2.5)
1.35
0.59–3.12
0.29
3 (1.7) 1 (0.6) 2 (1.1)
92 (1.7) 40 (0.7) 51 (0.9)
0.99 0.75 1.19
0.31–3.15 0.10–5.53 0.28–4.92
0.63 0.62 0.50
0.064
Values are given as number ± standard deviation or number (percentage). The χ2 test was used to evaluate the categorical variables. The t test was used for continuous variables. P b 0.05 was considered statistically significant. b
Table 2 Obstetric complications among women with and without uterine scar dehiscence during previous cesarean delivery.a,b
Abbreviations: CI, confidence interval; OR, odds ratio. a Values are given as number (percentage). b The Mantel-Haenszel procedure was used to obtain the ORs. P b 0.05 was considered statistically significant.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
J. Baron et al. / International Journal of Gynecology and Obstetrics xxx (2014) xxx–xxx
outcomes of the subsequent pregnancy. The key findings were that preterm deliveries, the need for blood transfusions, and peripartum hysterectomies were all markedly increased among women with a previous uterine scar dehiscence. The rate of previous uterine scar dehiscence was 3.2%, which is in accordance with previous reports [4–8]. Uterine rupture in the study population accrued in 1.1%, which was not significantly different from patients without a previous uterine scar dehiscence (P = 0.19). This observation might be attributed to the small absolute number of this rare complication. The increased rate of preterm deliveries observed among the women with uterine scar dehiscence might be explained by cautious clinical practice arising from concern for potential uterine rupture. Consequently, it is possible that if some of the women with previous uterine scar dehiscence had been allowed to continue to term, the occurrence of regular uterine contractions and spontaneous labor would have resulted in uterine rupture. Blood transfusion was more frequent among the group of women with uterine scar dehiscence. The need for blood transfusion could be attributed to blood loss during surgery rather than to anemia because the between-group difference in predelivery hemoglobin levels was not statistically significant. Gilliam et al. [15] previously identified an increased risk of placenta previa among women with a history of cesarean delivery. In the present study, a high prevalence of placenta previa was observed in both the women with previous uterine scar dehiscence and those without this complication (2.8% vs 1.8%); however, this difference was not statistically different (P = 0.24). The consequences of an abnormally adherent placenta (in all its forms) are severe as they are responsible for 41%–64% of all obstetric hysterectomies [16]. Nevertheless, no significant between-group difference in the prevalence of placenta accreta was detected in the present study. Preterm deliveries (either b 37 or b34 weeks of gestation) were more frequent in the uterine scar dehiscence group than in the comparator group. The mean gestational age was 36.1 ± 2.0 weeks among women with uterine scar dehiscence versus 37.0 ± 2.1 weeks among women without dehiscence (P b 0.001). Although fetal weight was lower in the group with previous uterine scar dehiscence, there was no significant between-group difference in the rate of serious fetal adverse outcomes. The rate of very low birth weight (b 1500 g) did not differ significantly between the two groups. One interpretation of these data is that although cesarean delivery tended to be performed early in the previous uterine scar dehiscence group, these preterm deliveries were sufficiently late in gestation to avoid severe fetal complications. The policy of the study center was that patients with two previous cesarean deliveries were not allowed a trial of vaginal labor. The hospital records did not clearly indicate the number of patients who developed spontaneous labor; however, the absolute number was likely to be small owing to strict hospital policy of not permitting a trial of labor following two or more cesarean deliveries. The physicians’ attempt to avoid the onset of regular uterine contractions and spontaneous labor is the most probable cause for early, planned cesarean delivery observed among the women with previous uterine scar dehiscence. A study conducted by Pollio et al. [2] reported that the scarred lower uterine segment of women with dehiscence displayed a number of biochemical changes. These changes included increased levels of collagen and decreased levels (or absence of) transforming growth factor, which might reflect alterations in the scarring process. In the present study, women of Bedouin Arab ethnicity had a higher rate of uterine scar dehiscence than did Jewish women. A possible explanation for this difference could be that changes in the structure of collagen might be dependent on ethnicity; however, this theory remains speculative as biopsy samples were not taken in the present study. The strengths of the present study include the sample size and the fact that the population investigated attended the same tertiary hospital. The large sample size allowed evaluation of the association
3
of a previous uterine scar dehiscence with several clinically important outcomes. At the Soroka University Medical Center, uterine scar closure is always performed with two layers. Use of the same technique reduced the possibility that surgical performance influenced the results. The present study also has some weaknesses that should be considered, mostly owing to the retrospective design. The first is that deliveries occurred over a timeframe of more than 20 years. During this period, it seems reasonable to assume that changes in obstetric practice and increased rates of cesarean delivery might have influenced the outcomes. However, as the comparator group was sampled from the same hospital and during the same time period as the women with uterine scar dehiscence, it is unlikely that this factor affected the results. Another potential weakness is the possibility of missing data. To minimize this effect, data were reported by the obstetrician directly after delivery and skilled medical secretaries reviewed the information before entering it into the database, thereby minimizing recall bias. Furthermore, coding was performed only after the relevant medical, hospital, and prenatal care records had been assessed. In summary, the findings of the present study suggest that uterine scar dehiscence in a previous pregnancy is a potential risk factor for iatrogenic preterm delivery, low birth weight, and peripartum hysterectomy in the following pregnancy. However, uterine scar dehiscence is not a risk factor for subsequent uterine rupture, placenta accreta, or perinatal mortality. Women with a history of uterine scar dehiscence should be advised about these possible complications before planning future pregnancies. Conflict of interest The authors report no conflict of interest. References [1] Scott JR. Vaginal birth after cesarean delivery: A common-sense approach. Obstet Gynecol 2011;118:342–50. [2] Pollio F, Staibano S, Mascolo M, Salvatore G, Persico F, De Falco M, et al. Uterine dehiscence in term pregnant patients with one previous cesarean delivery: Growth factor immunoexpression and collagen content in the scarred lower uterine segment. Am J Obstet Gynecol 2006;194(2):527–34. [3] Roberge S, Boutin A, Chaillet N, Moore L, Jastrow N, Demers S, et al. Systematic review of cesarean scar assessment in the nonpregnant state: Imaging techniques and uterine scar defect. Am J Perinatol 2012;29(6):465–71. [4] Madaan M, Agrawal S, Nigam A, Aggarwal R, Trivedi SS. Trial of labour after previous caesarean section: The predictive factors affecting outcome. J Obstet Gynaecol 2011;31(3):224–8. [5] Bashiri A, Burstein E, Rosen S, Smolin A, Sheiner E, Mazor M. Clinical significance of uterine scar dehiscence in women with previous cesarean delivery: Prevalence and independent risk factors. J Reprod Med 2008;53(1):8–14. [6] Ben Nagi J, Ofili-Yebovi D, Marsh M, Jurkovic D. First-trimester cesarean scar pregnancy evolving into placenta previa/accreta at term. J Ultrasound Med 2005;24(11): 1569–73. [7] Jurkovic D, Hillaby K, Woelfer B, Lawrence A, Salim R, Elson CJ. First-trimester diagnosis and management of pregnancies implanted into the lower uterine segment cesarean section scar. Ultrasound Obstet Gynecol 2003;21(3):220–7. [8] Armstrong V, Hansen WF, Van Voorhis BJ, Syrop CH. Detection of cesarean scars by transvaginal ultrasound. Obstet Gynecol 2003;101(1):61–5. [9] Landon MB, Hauth JC, Leveno KJ, Spong CY, Leindecker S, Varner MW, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med 2004;351(25):2581–9. [10] McMahon MJ, Luther ER, Bowes Jr WA, Olshan AF. Comparison of a trial of labor with an elective second cesarean section. N Engl J Med 1996;335(10):689–95. [11] Valentin L. Prediction of scar integrity and vaginal birth after caesarean delivery. Best Pract Res Clin Obstet Gynaecol 2013;27(2):285–95. [12] Ofir K, Sheiner E, Levy A, Katz M, Mazor M. Uterine rupture: Risk factors and pregnancy outcome. Am J Obstet Gynecol 2003;189(4):1042–6. [13] Ofir K, Sheiner E, Levy A, Katz M, Mazor M. Uterine rupture: Differences between a scarred and an unscarred uterus. Am J Obstet Gynecol 2004;191(2):425–9. [14] Ronel D, Wiznitzer A, Sergienko R, Zlotnik A, Sheiner E. Trends, risk factors and pregnancy outcome in women with uterine rupture. Arch Gynecol Obstet 2012;285(2): 317–21. [15] Gilliam M, Rosenberg D, Davis F. The likelihood of placenta previa with greater number of cesarean deliveries and higher parity. Obstet Gynecol 2002;99(6):976–80. [16] Zelop CM, Harlow BL, Frigoletto Jr FD, Safon LE, Saltzman DH. Emergency peripartum hysterectomy. Am J Obstet Gynecol 1993;168(5):1443–8.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
Contents lists available at ScienceDirect
International Journal of Gynecology and Obstetrics journal homepage: www.elsevier.com/locate/ijgo
CLINICAL ARTICLE
The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births☆ Joel Baron ⁎, Adi Y. Weintraub, Tamar Eshkoli, Reli Hershkovitz, Eyal Sheiner Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
a r t i c l e
i n f o
Article history: Received 20 July 2013 Received in revised form 15 February 2014 Accepted 17 April 2014 Keywords: Cesarean delivery Fetal complication Obstetric complication Risk factor Uterine rupture Uterine scar dehiscence
a b s t r a c t Objective: To determine whether women with a previous uterine scar dehiscence are at increased risk of adverse perinatal outcomes in the following delivery. Methods: A retrospective cohort study was conducted of all subsequent singleton cesarean deliveries performed at the Soroka University Medical Center, Beer-Sheva, Israel, between January 1, 1988, and December 31, 2011. Clinical and demographic characteristics, maternal obstetric complications, and fetal complications were evaluated among women with or without a previous documented uterine scar dehiscence. Results: Of the 5635 pregnancies associated with at least two previous cesarean deliveries, 180 (3.2%) occurred among women with a previous uterine scar dehiscence. Women with this condition in a prior pregnancy were more likely than those without previous uterine scar dehiscence to experience subsequent preterm delivery (86 [47.8%] vs 1350 [24.7%]; P b 0.001), low birth weight (47 [26.1%] vs 861 [15.8%]; P b 0.001), and peripartum hysterectomy (5 [2.8%] vs 20 [0.4%]; P b 0.001). Nevertheless, previous uterine scar dehiscence did not increase the risk of uterine rupture, placenta accreta, or adverse perinatal outcomes, such as low Apgar scores at 5 minutes and perinatal mortality. Conclusion: Uterine scar dehiscence in a previous pregnancy is a potential risk factor for preterm delivery, low birth weight, and peripartum hysterectomy in the following pregnancy. © 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction The number of cesarean deliveries performed has increased worldwide over time. For example, the rate recorded in the USA has risen from 5.0% in 1970 to 32.9% in 2009 [1]. Dehiscence of the uterine scar is a known complication of cesarean delivery. Various definitions of this condition are found in the literature for example: "a subperitoneal separation of the uterine scar, with the chorioamniotic membrane visible through the peritoneum" [2] and "the absence of the myometrium or the presence of an extremely thin myometrium diagnosed at the time of cesarean delivery" [3]. Uterine scar dehiscence is observed among 0.2%–4.3% of all pregnancies associated with a previous history of cesarean delivery [4–8] and can potentially lead to uterine rupture. The consequences of uterine rupture during a trial of vaginal delivery after cesarean delivery have been widely discussed in the literature and are associated with serious complications endangering both the mother and her offspring [9,10].
A study conducted by Landon et al. [9] reported a 0.38% perinatal morbidity rate following uterine rupture at term; furthermore, the intrapartum death rate was 0.03% and the rate of hypoxic–ischemic encephalopathy was 0.08%. Valentin et al. [11] found that uterine rupture was associated with a short interval between deliveries, a birth weight of 4000 g or over, induction of labor, oxytocin dose, and a thin lower uterine segment at 35–40 weeks of pregnancy; by contrast, a low risk of uterine rupture was noted among women with a previous vaginal delivery. In other studies, reported independent risk factors for uterine rupture included previous cesarean delivery, preterm delivery, malpresentation, parity, and dystocia during the first and second stages of labor [12–14]. Data regarding the consequences and complications of a previous uterine scar dehiscence on the following pregnancy are scarce. The aim of the present study was to investigate the maternal and perinatal outcomes in pregnancies associated with previous cesarean delivery and uterine scar dehiscence. 2. Materials and methods
☆ Abstract presented at the Society for Maternal-Fetal Medicine Annual Meeting, February 11–16, 2013, San Francisco, USA. ⁎ Corresponding author at: Department of Obstetrics and Gynecology, Soroka University Medical Center, POB 151, Beer Sheva 84101, Israel. Tel.: + 972 8 6400423; fax: +972 8 6403854. E-mail address: [email protected] (J. Baron).
A retrospective cohort study was conducted that compared the pregnancy outcomes of women with and without a previous uterine scar dehiscence who underwent a subsequent singleton cesarean delivery at the Soroka University Medical Center, Beer-Sheva, Israel, between
http://dx.doi.org/10.1016/j.ijgo.2014.02.022 0020-7292/© 2014 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
2
J. Baron et al. / International Journal of Gynecology and Obstetrics xxx (2014) xxx–xxx
January 1, 1998, and December 31, 2011. The Soroka University Medical Center ethics review board approved the present study; informed consent was not required owing to the retrospective design. The Soroka University Medical Center is the sole tertiary hospital in the Negev (the southern region of Israel) and it provides care for nearly all of the pregnancies that occur in this geographic area. Most women with one or more previous cesarean deliveries were evaluated in a pre-surgical clinic. The most recent surgical report was overviewed and an ultrasonographic examination performed if needed. The surgical team comprised highly skilled and experienced obstetricians, with at least one senior consultant present in the operating room during the procedure. All surgeons used the same uterine closure technique with double layer sutures. A computerized database was used to identify women who had previously undergone at least two cesarean deliveries at the Soroka University Medical Center. Patient information was recorded by the obstetrician immediately after delivery and reviewed by trained medical secretaries. Coding was performed after thorough evaluation of both prenatal medical care records and routine hospital documents. The outcomes of singleton pregnancies subsequent to at least two previous cesarean deliveries were examined to identify women either with or without a prior uterine scar dehiscence. A clinical diagnosis of uterine scar dehiscence was made in cases where a thin, transparent lower uterine segment was observed by the senior surgeon. Exclusion criteria included fewer than two cesarean deliveries and multiple gestations. Demographic and clinical characteristics included maternal age, ethnicity, gestational age, parity, neonatal sex, and birth weight. The pregnancy and labor complications and birth outcomes that were assessed in the present study included premature rupture of membranes, meconium-stained amniotic fluid, preterm delivery, placenta previa, placenta accreta, uterine rupture, peripartum hysterectomy, blood transfusion, low birth weight, low Apgar score at 5 minutes, and perinatal mortality. The data were analyzed using SPSS version 17.0 (SPSS Inc, Chicago, IL, USA). The χ2 test or Fisher exact test was used to evaluate the categorical variables, whereas the t test was used for the continuous variables. The Mantel-Haenszel procedure was used to obtain the odds ratio (OR). A P value below 0.05 was considered statistically significant. 3. Results During the study period, 5635 women had undergone at least two previous cesarean deliveries; of these, 180 women (3.2%) had a previous uterine scar dehiscence. The clinical and demographic characteristics of the present study cohort are presented in Table 1. The prevalence of uterine scar dehiscence was more frequent among women of Bedouin Arab ethnicity than those of Jewish ethnicity (P b 0.001).
Table 1 Clinical and demographic characteristics among women with and without uterine scar dehiscence during previous cesarean delivery.a Characteristic
Uterine scar dehiscence No uterine scar dehiscence P valueb (n = 180) (n = 5455)
Maternal age, y Ethnicity Bedouin Arab Jewish Parity 3–4 ≥5 Gestational age, wk Sex of neonate Female Male
32.0 ± 4.3
32.6 ± 4.9
133 (73.9) 47 (26.1)
3469 (63.6) 1986 (36.4)
b0.001
84 (46.7) 96 (53.3) 36.1 ± 2.0
2823 (51.8) 2632 (48.2) 37.0 ± 2.1
0.179
87 (48.3) 93 (51.7)
2675 (49.0) 2780 (51.0)
0.852
a
Complication
Uterine scar No uterine scar OR dehiscence dehiscence (n = 5455) (n = 180)
Polyhydramnion Breech presentation Premature rupture of membranes Meconium-stained amniotic fluid Severe pre-eclampsia toxemia Preterm delivery (b37 wk) Preterm delivery (b34 wk) Placenta accreta Placenta previa Placental abruption Postpartum hemorrhage Blood transfusion Anemia before delivery (Hb b10 mg/dL) Uterine rupture Peripartum hysterectomy
11 (6.1) 8 (4.4) 7 (3.9)
364 (6.7) 182 (3.3) 148 (2.7)
0.91 0.49–1.69 1.34 0.65–2.78 1.45 0.67–3.14
0.45 0.26 0.22
4 (2.2)
226 (4.1)
0.52 0.19–1.42
0.13
2 (1.1)
118 (2.2)
0.50 0.12–2.07
0.25
86 (47.8)
1350 (24.7)
2.78 2.06–3.75
b0.001
14 (7.8)
227 (4.2)
1.94 1.10–3.40
0.01
1 (0.6) 5 (2.8) 1 (0.6) 2 (1.1) 14 (7.8) 96 (53.3)
27 (0.5) 100 (1.8) 60 (1.1) 19 (0.3) 212 (3.9) 2661 (48.8)
1.12 1.53 0.50 3.21 2.08 1.20
0.59 0.24 0.41 0.14 0.01 0.13
2 (1.1) 5 (2.8)
23 (0.4) 20 (0.4)
0.001
95% CI
0.15–8.31 0.61–3.80 0.06–3.64 0.74–13.90 1.18–3.36 0.89–1.61
P value
2.65 0.62–11.34 0.19 7.74 2.88–20.92 b0.001
Abbreviations: CI, confidence interval; Hb, hemoglobin; OR, odds ratio. a Values are given as number (percentage). b The Mantel-Haenszel procedure was used to obtain the ORs. P b 0.05 was considered statistically significant.
The mean gestational age was 36.1 ± 2.0 weeks in the uterine scar dehiscence group versus 37.0 ± 2.1 weeks in the group without uterine scar dehiscence (P b 0.001). Obstetric complications of women with and without a previous uterine scar dehiscence are shown in Table 2. Previous uterine scar dehiscence was significantly associated with adverse pregnancy outcomes, including preterm delivery, peripartum hysterectomy, and the need for blood transfusion in the subsequent pregnancy. Neonates born following a pregnancy complicated by uterine scar dehiscence had significantly lower birth weight (b2500 g) than neonates whose mothers did not have this complication (Table 3). However, very low birth weight (b 1500 g), a 5-minute Apgar score below seven, and perinatal mortality did not differ between the two groups. 4. Discussion The aim of the present study was to investigate the influence of a previous uterine scar dehiscence on the obstetric and perinatal
Table 3 Fetal complications among women with and without uterine scar dehiscence during previous cesarean delivery.a,b Complication
Uterine scar dehiscence (n = 180)
No uterine scar dehiscence (n = 5455)
OR
95% CI
P value
Low birth weight (b2500 g) Very low birth weight (b1500 g) Low 5-minute Apgar score (b7) Perinatal mortality Prepartum death Postpartum death
47 (26.1)
861 (15.8)
1.88
1.34–2.65
b0.001
3 (1.7)
118 (2.2)
0.76
0.24–2.43
0.45
6 (3.3)
135 (2.5)
1.35
0.59–3.12
0.29
3 (1.7) 1 (0.6) 2 (1.1)
92 (1.7) 40 (0.7) 51 (0.9)
0.99 0.75 1.19
0.31–3.15 0.10–5.53 0.28–4.92
0.63 0.62 0.50
0.064
Values are given as number ± standard deviation or number (percentage). The χ2 test was used to evaluate the categorical variables. The t test was used for continuous variables. P b 0.05 was considered statistically significant. b
Table 2 Obstetric complications among women with and without uterine scar dehiscence during previous cesarean delivery.a,b
Abbreviations: CI, confidence interval; OR, odds ratio. a Values are given as number (percentage). b The Mantel-Haenszel procedure was used to obtain the ORs. P b 0.05 was considered statistically significant.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
J. Baron et al. / International Journal of Gynecology and Obstetrics xxx (2014) xxx–xxx
outcomes of the subsequent pregnancy. The key findings were that preterm deliveries, the need for blood transfusions, and peripartum hysterectomies were all markedly increased among women with a previous uterine scar dehiscence. The rate of previous uterine scar dehiscence was 3.2%, which is in accordance with previous reports [4–8]. Uterine rupture in the study population accrued in 1.1%, which was not significantly different from patients without a previous uterine scar dehiscence (P = 0.19). This observation might be attributed to the small absolute number of this rare complication. The increased rate of preterm deliveries observed among the women with uterine scar dehiscence might be explained by cautious clinical practice arising from concern for potential uterine rupture. Consequently, it is possible that if some of the women with previous uterine scar dehiscence had been allowed to continue to term, the occurrence of regular uterine contractions and spontaneous labor would have resulted in uterine rupture. Blood transfusion was more frequent among the group of women with uterine scar dehiscence. The need for blood transfusion could be attributed to blood loss during surgery rather than to anemia because the between-group difference in predelivery hemoglobin levels was not statistically significant. Gilliam et al. [15] previously identified an increased risk of placenta previa among women with a history of cesarean delivery. In the present study, a high prevalence of placenta previa was observed in both the women with previous uterine scar dehiscence and those without this complication (2.8% vs 1.8%); however, this difference was not statistically different (P = 0.24). The consequences of an abnormally adherent placenta (in all its forms) are severe as they are responsible for 41%–64% of all obstetric hysterectomies [16]. Nevertheless, no significant between-group difference in the prevalence of placenta accreta was detected in the present study. Preterm deliveries (either b 37 or b34 weeks of gestation) were more frequent in the uterine scar dehiscence group than in the comparator group. The mean gestational age was 36.1 ± 2.0 weeks among women with uterine scar dehiscence versus 37.0 ± 2.1 weeks among women without dehiscence (P b 0.001). Although fetal weight was lower in the group with previous uterine scar dehiscence, there was no significant between-group difference in the rate of serious fetal adverse outcomes. The rate of very low birth weight (b 1500 g) did not differ significantly between the two groups. One interpretation of these data is that although cesarean delivery tended to be performed early in the previous uterine scar dehiscence group, these preterm deliveries were sufficiently late in gestation to avoid severe fetal complications. The policy of the study center was that patients with two previous cesarean deliveries were not allowed a trial of vaginal labor. The hospital records did not clearly indicate the number of patients who developed spontaneous labor; however, the absolute number was likely to be small owing to strict hospital policy of not permitting a trial of labor following two or more cesarean deliveries. The physicians’ attempt to avoid the onset of regular uterine contractions and spontaneous labor is the most probable cause for early, planned cesarean delivery observed among the women with previous uterine scar dehiscence. A study conducted by Pollio et al. [2] reported that the scarred lower uterine segment of women with dehiscence displayed a number of biochemical changes. These changes included increased levels of collagen and decreased levels (or absence of) transforming growth factor, which might reflect alterations in the scarring process. In the present study, women of Bedouin Arab ethnicity had a higher rate of uterine scar dehiscence than did Jewish women. A possible explanation for this difference could be that changes in the structure of collagen might be dependent on ethnicity; however, this theory remains speculative as biopsy samples were not taken in the present study. The strengths of the present study include the sample size and the fact that the population investigated attended the same tertiary hospital. The large sample size allowed evaluation of the association
3
of a previous uterine scar dehiscence with several clinically important outcomes. At the Soroka University Medical Center, uterine scar closure is always performed with two layers. Use of the same technique reduced the possibility that surgical performance influenced the results. The present study also has some weaknesses that should be considered, mostly owing to the retrospective design. The first is that deliveries occurred over a timeframe of more than 20 years. During this period, it seems reasonable to assume that changes in obstetric practice and increased rates of cesarean delivery might have influenced the outcomes. However, as the comparator group was sampled from the same hospital and during the same time period as the women with uterine scar dehiscence, it is unlikely that this factor affected the results. Another potential weakness is the possibility of missing data. To minimize this effect, data were reported by the obstetrician directly after delivery and skilled medical secretaries reviewed the information before entering it into the database, thereby minimizing recall bias. Furthermore, coding was performed only after the relevant medical, hospital, and prenatal care records had been assessed. In summary, the findings of the present study suggest that uterine scar dehiscence in a previous pregnancy is a potential risk factor for iatrogenic preterm delivery, low birth weight, and peripartum hysterectomy in the following pregnancy. However, uterine scar dehiscence is not a risk factor for subsequent uterine rupture, placenta accreta, or perinatal mortality. Women with a history of uterine scar dehiscence should be advised about these possible complications before planning future pregnancies. Conflict of interest The authors report no conflict of interest. References [1] Scott JR. Vaginal birth after cesarean delivery: A common-sense approach. Obstet Gynecol 2011;118:342–50. [2] Pollio F, Staibano S, Mascolo M, Salvatore G, Persico F, De Falco M, et al. Uterine dehiscence in term pregnant patients with one previous cesarean delivery: Growth factor immunoexpression and collagen content in the scarred lower uterine segment. Am J Obstet Gynecol 2006;194(2):527–34. [3] Roberge S, Boutin A, Chaillet N, Moore L, Jastrow N, Demers S, et al. Systematic review of cesarean scar assessment in the nonpregnant state: Imaging techniques and uterine scar defect. Am J Perinatol 2012;29(6):465–71. [4] Madaan M, Agrawal S, Nigam A, Aggarwal R, Trivedi SS. Trial of labour after previous caesarean section: The predictive factors affecting outcome. J Obstet Gynaecol 2011;31(3):224–8. [5] Bashiri A, Burstein E, Rosen S, Smolin A, Sheiner E, Mazor M. Clinical significance of uterine scar dehiscence in women with previous cesarean delivery: Prevalence and independent risk factors. J Reprod Med 2008;53(1):8–14. [6] Ben Nagi J, Ofili-Yebovi D, Marsh M, Jurkovic D. First-trimester cesarean scar pregnancy evolving into placenta previa/accreta at term. J Ultrasound Med 2005;24(11): 1569–73. [7] Jurkovic D, Hillaby K, Woelfer B, Lawrence A, Salim R, Elson CJ. First-trimester diagnosis and management of pregnancies implanted into the lower uterine segment cesarean section scar. Ultrasound Obstet Gynecol 2003;21(3):220–7. [8] Armstrong V, Hansen WF, Van Voorhis BJ, Syrop CH. Detection of cesarean scars by transvaginal ultrasound. Obstet Gynecol 2003;101(1):61–5. [9] Landon MB, Hauth JC, Leveno KJ, Spong CY, Leindecker S, Varner MW, et al. Maternal and perinatal outcomes associated with a trial of labor after prior cesarean delivery. N Engl J Med 2004;351(25):2581–9. [10] McMahon MJ, Luther ER, Bowes Jr WA, Olshan AF. Comparison of a trial of labor with an elective second cesarean section. N Engl J Med 1996;335(10):689–95. [11] Valentin L. Prediction of scar integrity and vaginal birth after caesarean delivery. Best Pract Res Clin Obstet Gynaecol 2013;27(2):285–95. [12] Ofir K, Sheiner E, Levy A, Katz M, Mazor M. Uterine rupture: Risk factors and pregnancy outcome. Am J Obstet Gynecol 2003;189(4):1042–6. [13] Ofir K, Sheiner E, Levy A, Katz M, Mazor M. Uterine rupture: Differences between a scarred and an unscarred uterus. Am J Obstet Gynecol 2004;191(2):425–9. [14] Ronel D, Wiznitzer A, Sergienko R, Zlotnik A, Sheiner E. Trends, risk factors and pregnancy outcome in women with uterine rupture. Arch Gynecol Obstet 2012;285(2): 317–21. [15] Gilliam M, Rosenberg D, Davis F. The likelihood of placenta previa with greater number of cesarean deliveries and higher parity. Obstet Gynecol 2002;99(6):976–80. [16] Zelop CM, Harlow BL, Frigoletto Jr FD, Safon LE, Saltzman DH. Emergency peripartum hysterectomy. Am J Obstet Gynecol 1993;168(5):1443–8.
Please cite this article as: Baron J, et al, The consequences of previous uterine scar dehiscence and cesarean delivery on subsequent births, Int J Gynecol Obstet (2014), http://dx.doi.org/10.1016/j.ijgo.2014.02.022
