Case Report
Uterine Didelphys and Vaginal Birth After Cesarean Delivery Gary Altwerger, MD, Ashley M. Pritchard, MD, Jonathan D. Black, MD, MPH, and Anna K. Sfakianaki, MD, MPH BACKGROUND: Mu¨llerian anomalies are associated with adverse pregnancy outcomes. We discuss pregnancy in anomalous uteri, with a focus on uterine didelphys, in the setting of a prior cesarean delivery. CASE(S): A 30-year-old woman, gravida 2 para 1001, presented in latent labor at 40 1/7 weeks of gestation. Her first pregnancy was in the right horn of a didelphic uterus and resulted in a cesarean delivery in the setting of chorioamnionitis remote from delivery. The current pregnancy was in the left horn and resulted in a vacuumassisted vaginal delivery after spontaneous labor. CONCLUSION: There is sparse literature on a trial of labor after cesarean delivery in a uterine didelphys. (Obstet Gynecol 2015;125:157–9) DOI: 10.1097/AOG.0000000000000505
M
üllerian anomalies arise when the müllerian ducts fail to properly develop during embryogenesis. They exist in many permutations; there may be incomplete fusion, failure of growth, or incomplete regression of a septum after fusion of the müllerian ducts. The reported incidence of a müllerian anomaly is less than 3.4%, although the true incidence is unknown, because many cases, particularly those with a normal pregnancy outcome, go undiagnosed.1 Didelphic uterus occurs in 5% of patients with known müllerian anomalies.1 A didelphic uterus is the result of complete lack of fusion of the müllerian ducts and consists of two cervices and two uterine cavities, both of which can carry a full-term pregnancy. From the Department of Obstetrics and Gynecology and Section of MaternalFetal Medicine, Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut. Corresponding author: Jonathan D. Black, MD, MPH, P.O. Box 208063, New Haven, CT 06520-8063; e-mail: [email protected]. Financial Disclosure The authors did not report any potential conflicts of interest. © 2014 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/15
VOL. 125, NO. 1, JANUARY 2015
Teaching Points 1. A thorough and thoughtful evaluation of each pregnancy is necessary to counsel patients appropriately. 2. The didelphic uterus is a remarkable mu¨llerian anomaly and allows for unique obstetric outcomes.
Depending on the type of müllerian anomaly, a patient may present with primary amenorrhea, infertility, recurrent pregnancy loss, or a combination of these. Recurrent pregnancy loss may occur because of abnormal uterine cavity shape with altered blood supply. If embryo implantation is successful and the pregnancy proceeds from the first to second trimester, there may be adverse pregnancy outcomes such as fetal growth restriction, preterm delivery, and malposition of the fetus. The different müllerian anomalies have varying pregnancy outcomes. Although didelphic uterus is less common among müllerian anomalies, pregnancy outcomes are improved when compared with septate or unicornuate uterus; about 60–70% of pregnancies in a didelphic uterus result in a viable pregnancy.2 This improved outcome is probably due to increased blood supply through collateral circulation existing between the left and right uterine horn.2,3 A 2007 retrospective population-based study compared the risks of trial of labor after cesarean delivery (TOLAC) among müllerian anomalies to the general population and found the TOLAC was lower among women with müllerian anomalies (P,.001).4 However, in those attempting TOLAC, there was no difference in the rate of vaginal deliveries in müllerian anomalous uteri (61.4%) compared with normal uteri (71.7%; P5.054). The vaginal birth after cesarean delivery rate may have been lower in anomalous uteri because of fetal malpresentation or physician’s fear of rupture while allowing a hysterotomized anomalous uterus to undergo the stresses of labor. The risks of uterine rupture in the anomalous uteri were unchanged from the general population, and no uterine rupture was seen among the 165 cases with müllerian anomalies. In patients with didelphic uterus, the pregnancy may present in either uterine horn. Additionally, the location may vary between pregnancies. In cases of TOLAC in a didelphic uterus, the effect of a cesarean scar in one horn on the pregnancy in the contralateral horn is unknown.
OBSTETRICS & GYNECOLOGY
157
CASE A 30-year-old woman, gravida 2 para 1001, presented to labor and delivery with leakage of fluid, regular contractions, and vaginal spotting at 40 1/7 weeks of gestation. Rupture of membranes was confirmed, and the patient was noted to be 4 cm dilated, 90% effaced, and with the presenting part (vertex) at 21 station by digital examination. Her medical history was complicated by didelphic uterus with longitudinal vaginal septum, congenitally absent left kidney, and spina bifida occulta. Her obstetric history was significant for one prior pregnancy in the right horn of a didelphic uterus. In reviewing that pregnancy, she had a cesarean delivery at 40 weeks of gestation. She had progressed to 4-cm dilatation of the right cervix, but owing to persistent category 2 fetal heart tracing remote from delivery, and to prolonged labor (40 hours) complicated by chorioamnionitis, the patient underwent a primary low transverse cesarean delivery. During the delivery, the hysterotomy was developed in the lower uterine segment of the right horn. At the time of repair, a small extension into the lower uterine segment of the left horn was noted. The hysterotomy and extension were both repaired with a twolayer closure. The neonate was delivered in the occiput posterior position and weighed 2,860 g. The current pregnancy was in the left uterine horn and the patient desired a TOLAC. During her antenatal course she was informed on the lack of data regarding TOLAC in the setting of uterine didelphys and counseled on the uncertain effect of a hysterotomy scar in the contralateral horn on the current pregnancy. She opted for a TOLAC. After rupture of membranes was confirmed at presentation, she spontaneously went into labor, and over the next 18 hours received epidural anesthesia and progressed to 10 cm dilatation. She pushed for 4 hours with descent of fetal vertex to +3 station. After counseling regarding an assisted vaginal delivery, she delivered a viable, 2,980-g male neonate with 1-minute and 5-minute Apgar scores of 9 and 9, respectively, from the occiput posterior position using vacuum-assisted vaginal delivery. A second-degree laceration was noted and the vaginal septum was intact. The laceration was repaired in the standard fashion. Her postpartum course was uncomplicated.
DISCUSSION Our case depicts a unique case of a successful vaginal birth after cesarean delivery in the previously nulligravid (the former pregnancy was in the contralateral horn) uterine horn of a didelphic uterus. Counseling patients who are considering a TOLAC must include discussion about the risk of uterine rupture, risk of hysterectomy, risk of permanent neurologic impairment of the newborn, risk of failure of labor, and additional maternal or fetal complications. Given the patient’s history, the counseling was further complicated by the current pregnancy residing in the horn
158
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where the previous hysterotomy had extended. We considered three main questions: What is the risk of rupture for a didelphys uterus? What are the chances of successful labor in a didelphys uterus? What is the risk of a didelphys uterus rupturing during a TOLAC? The rupture rate in an unscarred didelphys uterus approaches the rupture rate (1/15,000) in an unscarred, nonanomalous uterus. This was concluded after a review of the literature produced only two cases detailing uterine rupture in an unscarred didelphys uterus. The first case report detailed a uterine rupture at 20 weeks of gestation that occurred in the setting of placenta percreta, a known risk factor for uterine rupture (in that case the didelphys uterus was not thought to be the sole causal factor for rupture).5 The second case was reported in 1953.6 Given the limited data, it appears that an unscarred uterine horn is capable of undergoing labor without an increased risk of rupture. The unscarred, nondisrupted myometrium is composed of cells that communicate through gap junctions. These gap junctions propagate contractions that begin in the cornual region7 and travel down and across the uterus to the lower uterine segment. This results in normal labor.8 If there is lack of cell-to-cell communication, as in the case of separate horns of a didelphys uterus, the myometrium may not retain its ability to contract in synchrony.9 However, there are no data to suggest that synchronous contractions of a didelphys uterus are necessary to expel a fetus from one horn, and in fact, in the case of twins in separate horns, asynchronous contractions allowed twins to be delivered at an interval of 66 days.10 Thus, contractions generated by a didelphys uterus with unscarred myometrium hypothetically have enough strength and frequency to expel a fetus from either horn. In this case, we need to consider the prior cesarean scar. If the current gestation resides in the scarred horn then we treat and counsel the patient as we would for a routine TOLAC. However, the question remains: Does the now parous horn retain the ability to expel a fetus? As discussed above, if intact, it probably has the strength and frequency to do so, but there was also the extension that occurred during the cesarean delivery, and the subsequent scar formation. Scar tissue results in disrupted communication between myometrial cells and alterations in blood flow, which can decrease the force of contractions generated by myometrial cells.2,11 Additionally, there is likely a disruption in communication through gap junctions. Therefore we can hypothesize that fibrotic scar tissue in the myometrium may lead to weaker and less
OBSTETRICS & GYNECOLOGY
coordinated contractions in a scarred uterus by altering blood flow and disrupting communication between myometrial cells. However, this extension was at the inferior edge of the lower uterine segment, a location inconsequential to the laboring uterus’ ability to contract. Thus, the now-parous uterus was still able to initiate strong and coordinated contractions. As discussed, the risk of uterine rupture during TOLAC is similar in women with müllerian anomalies compared with those without.4 However, the rate of vaginal birth in women with müllerian anomalies is lower. Repeat cesarean deliveries occur more frequently in patients with müllerian anomalies because of fetal malpresentation, but may also occur due to physician discomfort; a physician may be uncomfortable with labor in an anomalous uterus secondary to presumed inability of the myometrium to function. A case series by Heinonen followed 26 patients with uterine didelphys, 18 of whom achieved pregnancy. Of the 40 pregnancies that followed, breech presentation occurred in 43% and cesarean delivery was performed in 82% of pregnancies. Breech presentation represented fewer than half of the indications for cesarean deliveries; the majority of cesareans were completed for failed labor and repeat cesarean deliveries.12 Another study identified a group of 68 pregnancies with major fusion abnormalities, of which uterine didelphys accounted for approximately 10%. In this group, 32.4% of fetuses exhibited malpresentation. Interestingly, the rate of cesarean delivery was 64.7%. Among those who attempted a trial of labor, the cesarean delivery rate was 24.1%. In the group undergoing a trial of labor resulting in cesarean delivery, arrest of labor was identified in three patients (43%), and nonreassuring fetal heart rate in four patients (57%).13 Given the nature of the study, there may have been an element of physician discomfort that was not accounted for. Nonetheless, the cesarean delivery rate was lower in the TOLAC group, indicating that TOLAC may be a reasonable option in these patients. Although there may be a lower likelihood of successful TOLAC in patients with uterus didelphys, there are no overt contraindications to a TOLAC. Our patient desired a TOLAC, and if counseled
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appropriately with the available evidence, she and other similar patients deserve the opportunity to attempt a TOLAC. Given that cesarean deliveries currently represent 30% of all deliveries, physicians must consider opportunities to lower the rate of this major abdominal surgery. This is a circumstance, albeit rare, where we can make progress.2 REFERENCES 1. Simón C, Martinez L, Pardo F, Tortajada M, Pellicer A. Müllerian defects in women with normal reproductive outcome. Fertil Steril 1991;56:1192–3. 2. Cunningham FG, Leveno K, Bloom S, Hauth J, Rouse D, Spong C. Williams obstetrics. 23rd ed. New York (NY): McGraw-Hill Professional; 2010. 3. Hoffman B, Schorge J, Schaffer J, Halvorson L, Bradshaw K, Cunningham FG. Williams gynecology. 2nd ed. New York (NY): McGraw-Hill Professional; 2012. 4. Erez O, Dukler D, Novack L, Rozen A, Zolotnik L, Bashiri A, et al. Trial of labor and vaginal birth after cesarean section in patients with uterine Müllerian anomalies: a population-based study. Am J Obstet Gynecol 2007;196:537.e1–11. 5. Martinez-Garza PA, Robles-Landa LP, Roca-Cabrera M, VisagCastillo VJ, Reyes-Espejel L, Garcia-Vivanco D. Spontaneous uterine rupture: report of two cases. Cir Cir 2012;80:81–5. 6. Mitropol’skiĭ NK, Burde BI. Case of rupture of the pregnant uterus didelphys. Akush Ginekol (Mosk) 1953;5:80–1. 7. Caldeyro-Barcia R, Alvarez H. New findings on physiology, physiopathology, and pharmacology of the human uterus. An Fac Med Univ Repub Montev Urug 1953;38:383–400. 8. Reynolds SR, Hellman LM, Bruns P. Estimation of work in different uterine segments during labor. Arch Int Pharmacodyn Ther 1949;78:203–9. 9. Maki Y, Furukawa S, Sameshima H, Ikenoue T. Independent uterine contractions in simultaneous twin pregnancy in each horn of the uterus didelphys. J Obstet Gynaecol Res 2014;40: 836–9. 10. Nohara M, Nakayama M, Masamoto H, Nakazato K, Sakumoto K, Kanazawa K. Twin pregnancy in each half of a uterus didelphys with a delivery interval of 66 days. BJOG 2003;110:331–2. 11. Larcombe-McDouall JB, Harrison N, Wray S. The in vivo relationship between blood flow, contractions, pH and metabolites in the rat uterus. Pflugers Arch 1998;435:810–7. 12. Heinonen PK. Uterus didelphys: a report of 26 cases. Eur J Obstet Gynecol Reprod Biol 1984;17:345–50. 13. Fox NS, Roman AS, Stern EM, Gerber RS, Saltzman DH, Rebarber A. Type of congenital uterine anomaly and adverse pregnancy outcomes. J Matern Fetal Neonatal Med 2014;27: 949–53.
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159
Uterine Didelphys and Vaginal Birth After Cesarean Delivery Gary Altwerger, MD, Ashley M. Pritchard, MD, Jonathan D. Black, MD, MPH, and Anna K. Sfakianaki, MD, MPH BACKGROUND: Mu¨llerian anomalies are associated with adverse pregnancy outcomes. We discuss pregnancy in anomalous uteri, with a focus on uterine didelphys, in the setting of a prior cesarean delivery. CASE(S): A 30-year-old woman, gravida 2 para 1001, presented in latent labor at 40 1/7 weeks of gestation. Her first pregnancy was in the right horn of a didelphic uterus and resulted in a cesarean delivery in the setting of chorioamnionitis remote from delivery. The current pregnancy was in the left horn and resulted in a vacuumassisted vaginal delivery after spontaneous labor. CONCLUSION: There is sparse literature on a trial of labor after cesarean delivery in a uterine didelphys. (Obstet Gynecol 2015;125:157–9) DOI: 10.1097/AOG.0000000000000505
M
üllerian anomalies arise when the müllerian ducts fail to properly develop during embryogenesis. They exist in many permutations; there may be incomplete fusion, failure of growth, or incomplete regression of a septum after fusion of the müllerian ducts. The reported incidence of a müllerian anomaly is less than 3.4%, although the true incidence is unknown, because many cases, particularly those with a normal pregnancy outcome, go undiagnosed.1 Didelphic uterus occurs in 5% of patients with known müllerian anomalies.1 A didelphic uterus is the result of complete lack of fusion of the müllerian ducts and consists of two cervices and two uterine cavities, both of which can carry a full-term pregnancy. From the Department of Obstetrics and Gynecology and Section of MaternalFetal Medicine, Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut. Corresponding author: Jonathan D. Black, MD, MPH, P.O. Box 208063, New Haven, CT 06520-8063; e-mail: [email protected]. Financial Disclosure The authors did not report any potential conflicts of interest. © 2014 by The American College of Obstetricians and Gynecologists. Published by Lippincott Williams & Wilkins. ISSN: 0029-7844/15
VOL. 125, NO. 1, JANUARY 2015
Teaching Points 1. A thorough and thoughtful evaluation of each pregnancy is necessary to counsel patients appropriately. 2. The didelphic uterus is a remarkable mu¨llerian anomaly and allows for unique obstetric outcomes.
Depending on the type of müllerian anomaly, a patient may present with primary amenorrhea, infertility, recurrent pregnancy loss, or a combination of these. Recurrent pregnancy loss may occur because of abnormal uterine cavity shape with altered blood supply. If embryo implantation is successful and the pregnancy proceeds from the first to second trimester, there may be adverse pregnancy outcomes such as fetal growth restriction, preterm delivery, and malposition of the fetus. The different müllerian anomalies have varying pregnancy outcomes. Although didelphic uterus is less common among müllerian anomalies, pregnancy outcomes are improved when compared with septate or unicornuate uterus; about 60–70% of pregnancies in a didelphic uterus result in a viable pregnancy.2 This improved outcome is probably due to increased blood supply through collateral circulation existing between the left and right uterine horn.2,3 A 2007 retrospective population-based study compared the risks of trial of labor after cesarean delivery (TOLAC) among müllerian anomalies to the general population and found the TOLAC was lower among women with müllerian anomalies (P,.001).4 However, in those attempting TOLAC, there was no difference in the rate of vaginal deliveries in müllerian anomalous uteri (61.4%) compared with normal uteri (71.7%; P5.054). The vaginal birth after cesarean delivery rate may have been lower in anomalous uteri because of fetal malpresentation or physician’s fear of rupture while allowing a hysterotomized anomalous uterus to undergo the stresses of labor. The risks of uterine rupture in the anomalous uteri were unchanged from the general population, and no uterine rupture was seen among the 165 cases with müllerian anomalies. In patients with didelphic uterus, the pregnancy may present in either uterine horn. Additionally, the location may vary between pregnancies. In cases of TOLAC in a didelphic uterus, the effect of a cesarean scar in one horn on the pregnancy in the contralateral horn is unknown.
OBSTETRICS & GYNECOLOGY
157
CASE A 30-year-old woman, gravida 2 para 1001, presented to labor and delivery with leakage of fluid, regular contractions, and vaginal spotting at 40 1/7 weeks of gestation. Rupture of membranes was confirmed, and the patient was noted to be 4 cm dilated, 90% effaced, and with the presenting part (vertex) at 21 station by digital examination. Her medical history was complicated by didelphic uterus with longitudinal vaginal septum, congenitally absent left kidney, and spina bifida occulta. Her obstetric history was significant for one prior pregnancy in the right horn of a didelphic uterus. In reviewing that pregnancy, she had a cesarean delivery at 40 weeks of gestation. She had progressed to 4-cm dilatation of the right cervix, but owing to persistent category 2 fetal heart tracing remote from delivery, and to prolonged labor (40 hours) complicated by chorioamnionitis, the patient underwent a primary low transverse cesarean delivery. During the delivery, the hysterotomy was developed in the lower uterine segment of the right horn. At the time of repair, a small extension into the lower uterine segment of the left horn was noted. The hysterotomy and extension were both repaired with a twolayer closure. The neonate was delivered in the occiput posterior position and weighed 2,860 g. The current pregnancy was in the left uterine horn and the patient desired a TOLAC. During her antenatal course she was informed on the lack of data regarding TOLAC in the setting of uterine didelphys and counseled on the uncertain effect of a hysterotomy scar in the contralateral horn on the current pregnancy. She opted for a TOLAC. After rupture of membranes was confirmed at presentation, she spontaneously went into labor, and over the next 18 hours received epidural anesthesia and progressed to 10 cm dilatation. She pushed for 4 hours with descent of fetal vertex to +3 station. After counseling regarding an assisted vaginal delivery, she delivered a viable, 2,980-g male neonate with 1-minute and 5-minute Apgar scores of 9 and 9, respectively, from the occiput posterior position using vacuum-assisted vaginal delivery. A second-degree laceration was noted and the vaginal septum was intact. The laceration was repaired in the standard fashion. Her postpartum course was uncomplicated.
DISCUSSION Our case depicts a unique case of a successful vaginal birth after cesarean delivery in the previously nulligravid (the former pregnancy was in the contralateral horn) uterine horn of a didelphic uterus. Counseling patients who are considering a TOLAC must include discussion about the risk of uterine rupture, risk of hysterectomy, risk of permanent neurologic impairment of the newborn, risk of failure of labor, and additional maternal or fetal complications. Given the patient’s history, the counseling was further complicated by the current pregnancy residing in the horn
158
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where the previous hysterotomy had extended. We considered three main questions: What is the risk of rupture for a didelphys uterus? What are the chances of successful labor in a didelphys uterus? What is the risk of a didelphys uterus rupturing during a TOLAC? The rupture rate in an unscarred didelphys uterus approaches the rupture rate (1/15,000) in an unscarred, nonanomalous uterus. This was concluded after a review of the literature produced only two cases detailing uterine rupture in an unscarred didelphys uterus. The first case report detailed a uterine rupture at 20 weeks of gestation that occurred in the setting of placenta percreta, a known risk factor for uterine rupture (in that case the didelphys uterus was not thought to be the sole causal factor for rupture).5 The second case was reported in 1953.6 Given the limited data, it appears that an unscarred uterine horn is capable of undergoing labor without an increased risk of rupture. The unscarred, nondisrupted myometrium is composed of cells that communicate through gap junctions. These gap junctions propagate contractions that begin in the cornual region7 and travel down and across the uterus to the lower uterine segment. This results in normal labor.8 If there is lack of cell-to-cell communication, as in the case of separate horns of a didelphys uterus, the myometrium may not retain its ability to contract in synchrony.9 However, there are no data to suggest that synchronous contractions of a didelphys uterus are necessary to expel a fetus from one horn, and in fact, in the case of twins in separate horns, asynchronous contractions allowed twins to be delivered at an interval of 66 days.10 Thus, contractions generated by a didelphys uterus with unscarred myometrium hypothetically have enough strength and frequency to expel a fetus from either horn. In this case, we need to consider the prior cesarean scar. If the current gestation resides in the scarred horn then we treat and counsel the patient as we would for a routine TOLAC. However, the question remains: Does the now parous horn retain the ability to expel a fetus? As discussed above, if intact, it probably has the strength and frequency to do so, but there was also the extension that occurred during the cesarean delivery, and the subsequent scar formation. Scar tissue results in disrupted communication between myometrial cells and alterations in blood flow, which can decrease the force of contractions generated by myometrial cells.2,11 Additionally, there is likely a disruption in communication through gap junctions. Therefore we can hypothesize that fibrotic scar tissue in the myometrium may lead to weaker and less
OBSTETRICS & GYNECOLOGY
coordinated contractions in a scarred uterus by altering blood flow and disrupting communication between myometrial cells. However, this extension was at the inferior edge of the lower uterine segment, a location inconsequential to the laboring uterus’ ability to contract. Thus, the now-parous uterus was still able to initiate strong and coordinated contractions. As discussed, the risk of uterine rupture during TOLAC is similar in women with müllerian anomalies compared with those without.4 However, the rate of vaginal birth in women with müllerian anomalies is lower. Repeat cesarean deliveries occur more frequently in patients with müllerian anomalies because of fetal malpresentation, but may also occur due to physician discomfort; a physician may be uncomfortable with labor in an anomalous uterus secondary to presumed inability of the myometrium to function. A case series by Heinonen followed 26 patients with uterine didelphys, 18 of whom achieved pregnancy. Of the 40 pregnancies that followed, breech presentation occurred in 43% and cesarean delivery was performed in 82% of pregnancies. Breech presentation represented fewer than half of the indications for cesarean deliveries; the majority of cesareans were completed for failed labor and repeat cesarean deliveries.12 Another study identified a group of 68 pregnancies with major fusion abnormalities, of which uterine didelphys accounted for approximately 10%. In this group, 32.4% of fetuses exhibited malpresentation. Interestingly, the rate of cesarean delivery was 64.7%. Among those who attempted a trial of labor, the cesarean delivery rate was 24.1%. In the group undergoing a trial of labor resulting in cesarean delivery, arrest of labor was identified in three patients (43%), and nonreassuring fetal heart rate in four patients (57%).13 Given the nature of the study, there may have been an element of physician discomfort that was not accounted for. Nonetheless, the cesarean delivery rate was lower in the TOLAC group, indicating that TOLAC may be a reasonable option in these patients. Although there may be a lower likelihood of successful TOLAC in patients with uterus didelphys, there are no overt contraindications to a TOLAC. Our patient desired a TOLAC, and if counseled
VOL. 125, NO. 1, JANUARY 2015
appropriately with the available evidence, she and other similar patients deserve the opportunity to attempt a TOLAC. Given that cesarean deliveries currently represent 30% of all deliveries, physicians must consider opportunities to lower the rate of this major abdominal surgery. This is a circumstance, albeit rare, where we can make progress.2 REFERENCES 1. Simón C, Martinez L, Pardo F, Tortajada M, Pellicer A. Müllerian defects in women with normal reproductive outcome. Fertil Steril 1991;56:1192–3. 2. Cunningham FG, Leveno K, Bloom S, Hauth J, Rouse D, Spong C. Williams obstetrics. 23rd ed. New York (NY): McGraw-Hill Professional; 2010. 3. Hoffman B, Schorge J, Schaffer J, Halvorson L, Bradshaw K, Cunningham FG. Williams gynecology. 2nd ed. New York (NY): McGraw-Hill Professional; 2012. 4. Erez O, Dukler D, Novack L, Rozen A, Zolotnik L, Bashiri A, et al. Trial of labor and vaginal birth after cesarean section in patients with uterine Müllerian anomalies: a population-based study. Am J Obstet Gynecol 2007;196:537.e1–11. 5. Martinez-Garza PA, Robles-Landa LP, Roca-Cabrera M, VisagCastillo VJ, Reyes-Espejel L, Garcia-Vivanco D. Spontaneous uterine rupture: report of two cases. Cir Cir 2012;80:81–5. 6. Mitropol’skiĭ NK, Burde BI. Case of rupture of the pregnant uterus didelphys. Akush Ginekol (Mosk) 1953;5:80–1. 7. Caldeyro-Barcia R, Alvarez H. New findings on physiology, physiopathology, and pharmacology of the human uterus. An Fac Med Univ Repub Montev Urug 1953;38:383–400. 8. Reynolds SR, Hellman LM, Bruns P. Estimation of work in different uterine segments during labor. Arch Int Pharmacodyn Ther 1949;78:203–9. 9. Maki Y, Furukawa S, Sameshima H, Ikenoue T. Independent uterine contractions in simultaneous twin pregnancy in each horn of the uterus didelphys. J Obstet Gynaecol Res 2014;40: 836–9. 10. Nohara M, Nakayama M, Masamoto H, Nakazato K, Sakumoto K, Kanazawa K. Twin pregnancy in each half of a uterus didelphys with a delivery interval of 66 days. BJOG 2003;110:331–2. 11. Larcombe-McDouall JB, Harrison N, Wray S. The in vivo relationship between blood flow, contractions, pH and metabolites in the rat uterus. Pflugers Arch 1998;435:810–7. 12. Heinonen PK. Uterus didelphys: a report of 26 cases. Eur J Obstet Gynecol Reprod Biol 1984;17:345–50. 13. Fox NS, Roman AS, Stern EM, Gerber RS, Saltzman DH, Rebarber A. Type of congenital uterine anomaly and adverse pregnancy outcomes. J Matern Fetal Neonatal Med 2014;27: 949–53.
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![[Vaginal delivery after cesarean section].](/assets/img/hold.png)
