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Cesarean Scar Pregnancy: An Emerging Challenge
R E V I E W A R T I C L E
Cesarean Scar Pregnancy: An Emerging Challenge An-Shine Chao*, Angel Chao, Chin-Jung Wang The high prevalence of cesarean section is closely related to the increasing number of cesarean scar pregnancies. Ultrasound provides early and accurate diagnosis of an ectopic pregnancy in a cesarean section defect, allowing fertility preservation by using minimally invasive procedures and reducing maternal complications. The sonographic appearances, based on history and clinical symptoms, of a pregnancy implanted into a cesarean scar have to be recognized during routine obstetric practice. Laparoscopy or hysteroscopy management would be considered in early scar pregnancies. Combined systemic and intra-amniotic methotrexate injection also yield high success rates but require serial ultrasound investigations and follow-up with serum beta-hCG in the following weeks.
KEY WORDS — cesarean section, ectopic pregnancy, ultrasound ■ J Med Ultrasound 2008;16(4):268–271 ■
Introduction Cesarean scar pregnancy is defined as an ectopic pregnancy embedded in the myometrium of a previous cesarean scar. Prior to 1998, less than 20 cases of ectopic section scar pregnancies were reported in the English literature at MEDLINE. As the number of cesarean deliveries has been increasing steadily worldwide in recent decades, it is assumed that the consequences of abnormal adherent placenta would further increase [1–5]. In recent years
the first trimester diagnosis of an early pregnancy implantation into a deficient cesarean section scar has been described as a ‘cesarean scar pregnancy’.
Clinical Features Most cases may present from as early as 5–6 weeks, with a mean gestational age 7.5 ± 2.5 weeks, and have a silent clinical course or abnormal vaginal bleeding without abdominal discomfort. Late presentation
Received: September 24, 2008 Accepted: October 12, 2008 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Chang Gung University, Tao-Yuan, Taiwan. *Address correspondence to: An-Shine Chao, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Chang Gung University, 5 Fu-Shin Street, Kwei-Shan, Tao-Yuan 333, Taiwan. E-mail: [email protected]
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J Med Ultrasound 2008 • Vol 16 • No 4
©Elsevier & CTSUM. All rights reserved.
Scar Pregnancy would have profuse vaginal bleeding with abdominal pain or acute abdomen when the scar ruptured. Many cases may be misdiagnosed, leading to uterine curettage, followed by massive hemorrhage [3,6]. More than half of the reported cases had only one prior cesarean delivery.
Pathogenesis The most reasonable theories for explaining the implantation of a pregnancy within a cesarean fibrous tissue scar seems to be that the blastocyst enters into the myometrium through a microscopic dehiscent tract. This may be created throughout a trauma of a previous section, any other uterine surgery or by IVF and embryo transfer [7]. About 20% of women were found to have detectable myometrial thinning at the site of a previous cesarean section. In half of these women the defects were large, involving more than 50% of the myometrial thickness (Fig. 1). A history of multiple cesarean sections, uterine retroflexion and an inability to visualize all uterine scars in cases of multiple sections are the three variables associated with deficient scars. Scar implantations tend to occur in women with severe deficient scars who have a risk of implantation may be proportional to the size of the myometrial defect [5].
Fig. 1. Scar defect.
Ultrasound Diagnosis and Differential Diagnosis Cervical pregnancy and an intrauterine pregnancy with accreta are the two conditions, if a delay in either diagnosis or treatment, that could associate with significant maternal morbidity. A spontaneous abortion in progress can de diagnosed by serial changes and Doppler flow studies. The transvaginal sonographic criteria for an accurate diagnosis includes (1) the absence of a normal intrauterine pregnancy with an elevated level of serum beta-hCG, (2) an empty cervical canal, (3) on a sagittal view of the uterus showing a discontinuity in the anterior uterine wall when running through the gestational sac is demonstrated, and (4) the development of the gestational sac in the anterior wall of the lower uterine segment of the uterus with a diminished myometrium layer between the bladder and the gestational sac (Fig. 2) [1,7–9]. Combining an abdominal scan with a full bladder would obtain a clearer image of the ballooning of the lower uterine segment by gestation sac and its relation to the scar than images obtained using a vaginal probe (Fig. 3). Prominent peritrophoblastic flow has been shown on Doppler flow sonography [10]. 3-D power Doppler depicted peritrophoblastic flow surrounding
Fig. 2. (1) The absence of a normal intrauterine pregnancy with an elevated serum beta-hCG, (2) an empty cervical canal, (3) on a sagittal view of the uterus showing a discontinuity in the anterior uterine wall when running through the gestational sac is demonstrated. J Med Ultrasound 2008 • Vol 16 • No 4
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A.S. Chao, A. Chao, C.J. Wang
Fig. 3. Abdominal scan with a full bladder showing ballooning of the lower uterine segment by gestation sac (arrow). showing a well-formed shell [11]. Magnetic resonance imaging is used for late scar pregnancies when the differential diagnosis has to be made between abnormal placentation such as accreta, and is useful to show the extent of the attached placenta when it has ruptured into the peritoneum [7,12].
Management Medical and surgical modalities have been suggested and the choices depend upon the clinical situation, the availability of facilities and the experience of the medical personnel. Two conservative principle management options may be considered, i.e. the medical or the surgical. Open surgery was needed in emergent cases because of profuse hemorrhage. Surgical resection of a scar pregnancy with uterine preservation could be managed by different technical modalities [13]. Total hysterectomy was described for severe hemorrhage cases [14]. Minimally invasive approaches have been described. This includes hysteroscopy for visualization the uterine cavity combined with removal and aspiration of the ectopic mass by abdominal ultrasound or laparoscopy [15,16]. Expectant management is rarely successful. Two cases were reported to have been successful pregnancies but had maternal morbidities such as hysterectomy, ligation of iliac artery and transfusion [7,17].
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J Med Ultrasound 2008 • Vol 16 • No 4
The medical treatment mainly consists of methotraxate (MTX) either systemically or locally. A combined approach had limited systemic absorption by an ectopic pregnancy surrounded by a thick fibrous scar. This combined injection of MTX had succeeded in some cases with beta-hCG exceeding 10,000 mIU/ dL [3,7,11]. At least 6–8 weeks follow-up are needed for serial beta-hCG and ultrasound examination after MTX injection. A failure of systemic treatment by MTX causing persistent bleeding and hysterectomy was reported [18] or hysteroscopic resection in minor bleeding [19,20]. Embolization of uterine vessels may minimize such complications. An injection of MTX with or without another intragestational injection of potassium chloride for viable conceptus were used, and in combination of embolization or ligation of uterine or iliac artery [21–23]. Operative hysteroscopy and curettage are used for an early pregnancy not deeply implanted in the myometrium. Several reports describe the successful management of scar pregnancies by operative laparoscopy, all of them less than 10 gestational weeks [6]. Management of heterotopic cesarean scar pregnancy is an extreme challenge when the preservation of the concurrent intrauterine pregnancy is wanted. Three cases were performed by KCl injection or fine needle aspiration into the heterotopic cesarean scar pregnancy in IVF-ET twins with successful preservation of the intrauterine pregnancy [24–26]. A successful case of laparoscopic management intrauterine gestation to a term delivery after a heterotopic cesarean scar pregnancy was reported [27].
Conclusion Cesarean scar pregnancies are more commonly encountered in recent decade. Women who have had a history of previous cesarean section, and an early first trimester transvaginal ultrasound are advised to confirm the intrauterine location of the implantation site. Either surgical or combined systemic and intragestational MTX were successful in the treatment of these early unruptured cesarean scar pregnancies.
Scar Pregnancy
Acknowledgments We acknowledge Ms H C Liao for preparing this manuscript.
References 1. Fylstra DL. Ectopic pregnancy within a cesarean scar: a review. Obstet Gynecol Surv 2002;57:537–43. 2. Seow KM, Huang LW, Lin YH, et al. Cesarean scar pregnancy: issues in management. Ultrasound Obstet Gynecol 2004;23:247–53. 3. Rotas MA, Haberman S, Levgur M. Cesarean scar ectopic pregnancies: etiology, diagnosis, and management. Obstet Gynecol 2006;107:1373–81. 4. Jiao LZ, Zhao J, Wan XR, et al. Diagnosis and treatment of cesarean scar pregnancy. Chin Med Sci J 2008;23:10–5. 5. Ofili-Yebovi D, Ben-Nagi J, Sawyer E, et al. Deficient lower-segment cesarean section scars: prevalence and risk factors. Ultrasound Obstet Gynecol 2008;31:72–7. 6. Halperin R, Schneider D, Mendlovic S, et al. Uterinepreserving emergency surgery for cesarean scar pregnancies: another medical solution to an iatrogenic problem. Fertil Steril 2008; Apr 26. [Epub ahead of print] 7. Maymon R, Halperin R, Mendlovic S, et al. Ectopic pregnancies in caesarean section scars: the 8 year experience of one medical centre. Hum Reprod 2004;19:278–84. 8. Vial Y, Petignat P, Hohlfeld P. Pregnancy in a cesarean scar. Ultrasound Obstet Gynecol 2000;16:592–3. 9. Jurkovic D, Hillaby K, Woelfer B, et al. First-trimester diagnosis and management of pregnancies implanted into the lower uterine segment cesarean section scar. Ultrasound Obstet Gynecol 2003;21:220–7. 10. Nawroth F, Foth D, Wilhelm L, et al. Conservative treatment of ectopic pregnancy in a cesarean section scar with methotrexate: a case report. Eur J Obstet Gynecol Reprod Biol 2001;99:135–7. 11. Pascual MA, Hereter L, Graupera B, et al. Threedimensional power Doppler ultrasound diagnosis and conservative treatment of ectopic pregnancy in a cesarean section scar. Fertil Steril 2007;88:706 e5–7. 12. Teng HC, Kumar G, Ramli NM. A viable secondary intra-abdominal pregnancy resulting from rupture of uterine scar: role of MRI. Br J Radiol 2007;80:e134–6. 13. Rempen A, Albert P. [Diagnosis and therapy of an in the cesarean section scar implanted early pregnancy]. Z Geburtshilfe Perinatol 1990;194:46–8. 14. Larsen JV, Solomon MH. Pregnancy in a uterine scar sacculus—an unusual cause of postabortal haemorrhage. A case report. S Afr Med J 1978;53:142–3.
15. Lee CL, Wang CJ, Chao A, et al. Laparoscopic management of an ectopic pregnancy in a previous caesarean section scar. Hum Reprod 1999;14:1234–6. 16. Wang YL, Su TH, Chen HS. Operative laparoscopy for unruptured ectopic pregnancy in a caesarean scar. BJOG 2006;113:1035–8. 17. Herman A, Weinraub Z, Avrech O, et al. Follow up and outcome of isthmic pregnancy located in a previous caesarean section scar. Br J Obstet Gynaecol 1995;102: 839–41. 18. Lai YM, Lee JD, Lee CL, et al. An ectopic pregnancy embedded in the myometrium of a previous cesarean section scar. Acta Obstet Gynecol Scand 1995;74:573–6. 19. Chao A, Chao AS, Wang ST, et al. Mifepristoneinduced abortion in one horn and a growing fetus in another horn in a patient with a twin pregnancy in a bicornuate uterus. Fertil Steril 2006;86:1764 e3–5. 20. Ozkan S, Caliskan E, Ozeren S, et al. Three-dimensional ultrasonographic diagnosis and hysteroscopic management of a viable cesarean scar ectopic pregnancy. J Obstet Gynaecol Res 2007;33:873–7. 21. Yang MJ, Jeng MH. Combination of transarterial embolization of uterine arteries and conservative surgical treatment for pregnancy in a cesarean section scar. A report of 3 cases. J Reprod Med 2003;48:213–6. 22. Ghezzi F, Raio L, Mueller MD, et al. Vaginal extraction of pelvic masses following operative laparoscopy. Surg Endosc 2002;16:1691–6. 23. Hois EL, Hibbeln JF, Sclamberg JS. Spontaneous twin tubal ectopic gestation. J Clin Ultrasound 2006;34:352–5. 24. Salomon LJ, Fernandez H, Chauveaud A, et al. Successful management of a heterotopic caesarean scar pregnancy: potassium chloride injection with preservation of the intrauterine gestation: case report. Hum Reprod 2003;18:189–91. 25. Hsieh BC, Lin YH, Huang LW, et al. Cervical pregnancy after in vitro fertilization and embryo transfer successfully treated with methotrexate and intracervical injection of vasopressin. Acta Obstet Gynecol Scand 2004;83:112–4. 26. Wang CN, Chen CK, Wang HS, et al. Successful management of heterotopic cesarean scar pregnancy combined with intrauterine pregnancy after in vitro fertilization-embryo transfer. Fertil Steril 2007;88:706 e13–6. 27. Demirel LC, Bodur H, Selam B, et al. Laparoscopic management of heterotopic cesarean scar pregnancy with preservation of intrauterine gestation and delivery at term: case report. Fertil Steril 2008; Mar 17. [Epub ahead of print]
J Med Ultrasound 2008 • Vol 16 • No 4
271
Cesarean Scar Pregnancy: An Emerging Challenge An-Shine Chao*, Angel Chao, Chin-Jung Wang The high prevalence of cesarean section is closely related to the increasing number of cesarean scar pregnancies. Ultrasound provides early and accurate diagnosis of an ectopic pregnancy in a cesarean section defect, allowing fertility preservation by using minimally invasive procedures and reducing maternal complications. The sonographic appearances, based on history and clinical symptoms, of a pregnancy implanted into a cesarean scar have to be recognized during routine obstetric practice. Laparoscopy or hysteroscopy management would be considered in early scar pregnancies. Combined systemic and intra-amniotic methotrexate injection also yield high success rates but require serial ultrasound investigations and follow-up with serum beta-hCG in the following weeks.
KEY WORDS — cesarean section, ectopic pregnancy, ultrasound ■ J Med Ultrasound 2008;16(4):268–271 ■
Introduction Cesarean scar pregnancy is defined as an ectopic pregnancy embedded in the myometrium of a previous cesarean scar. Prior to 1998, less than 20 cases of ectopic section scar pregnancies were reported in the English literature at MEDLINE. As the number of cesarean deliveries has been increasing steadily worldwide in recent decades, it is assumed that the consequences of abnormal adherent placenta would further increase [1–5]. In recent years
the first trimester diagnosis of an early pregnancy implantation into a deficient cesarean section scar has been described as a ‘cesarean scar pregnancy’.
Clinical Features Most cases may present from as early as 5–6 weeks, with a mean gestational age 7.5 ± 2.5 weeks, and have a silent clinical course or abnormal vaginal bleeding without abdominal discomfort. Late presentation
Received: September 24, 2008 Accepted: October 12, 2008 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Chang Gung University, Tao-Yuan, Taiwan. *Address correspondence to: An-Shine Chao, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Chang Gung University, 5 Fu-Shin Street, Kwei-Shan, Tao-Yuan 333, Taiwan. E-mail: [email protected]
268
J Med Ultrasound 2008 • Vol 16 • No 4
©Elsevier & CTSUM. All rights reserved.
Scar Pregnancy would have profuse vaginal bleeding with abdominal pain or acute abdomen when the scar ruptured. Many cases may be misdiagnosed, leading to uterine curettage, followed by massive hemorrhage [3,6]. More than half of the reported cases had only one prior cesarean delivery.
Pathogenesis The most reasonable theories for explaining the implantation of a pregnancy within a cesarean fibrous tissue scar seems to be that the blastocyst enters into the myometrium through a microscopic dehiscent tract. This may be created throughout a trauma of a previous section, any other uterine surgery or by IVF and embryo transfer [7]. About 20% of women were found to have detectable myometrial thinning at the site of a previous cesarean section. In half of these women the defects were large, involving more than 50% of the myometrial thickness (Fig. 1). A history of multiple cesarean sections, uterine retroflexion and an inability to visualize all uterine scars in cases of multiple sections are the three variables associated with deficient scars. Scar implantations tend to occur in women with severe deficient scars who have a risk of implantation may be proportional to the size of the myometrial defect [5].
Fig. 1. Scar defect.
Ultrasound Diagnosis and Differential Diagnosis Cervical pregnancy and an intrauterine pregnancy with accreta are the two conditions, if a delay in either diagnosis or treatment, that could associate with significant maternal morbidity. A spontaneous abortion in progress can de diagnosed by serial changes and Doppler flow studies. The transvaginal sonographic criteria for an accurate diagnosis includes (1) the absence of a normal intrauterine pregnancy with an elevated level of serum beta-hCG, (2) an empty cervical canal, (3) on a sagittal view of the uterus showing a discontinuity in the anterior uterine wall when running through the gestational sac is demonstrated, and (4) the development of the gestational sac in the anterior wall of the lower uterine segment of the uterus with a diminished myometrium layer between the bladder and the gestational sac (Fig. 2) [1,7–9]. Combining an abdominal scan with a full bladder would obtain a clearer image of the ballooning of the lower uterine segment by gestation sac and its relation to the scar than images obtained using a vaginal probe (Fig. 3). Prominent peritrophoblastic flow has been shown on Doppler flow sonography [10]. 3-D power Doppler depicted peritrophoblastic flow surrounding
Fig. 2. (1) The absence of a normal intrauterine pregnancy with an elevated serum beta-hCG, (2) an empty cervical canal, (3) on a sagittal view of the uterus showing a discontinuity in the anterior uterine wall when running through the gestational sac is demonstrated. J Med Ultrasound 2008 • Vol 16 • No 4
269
A.S. Chao, A. Chao, C.J. Wang
Fig. 3. Abdominal scan with a full bladder showing ballooning of the lower uterine segment by gestation sac (arrow). showing a well-formed shell [11]. Magnetic resonance imaging is used for late scar pregnancies when the differential diagnosis has to be made between abnormal placentation such as accreta, and is useful to show the extent of the attached placenta when it has ruptured into the peritoneum [7,12].
Management Medical and surgical modalities have been suggested and the choices depend upon the clinical situation, the availability of facilities and the experience of the medical personnel. Two conservative principle management options may be considered, i.e. the medical or the surgical. Open surgery was needed in emergent cases because of profuse hemorrhage. Surgical resection of a scar pregnancy with uterine preservation could be managed by different technical modalities [13]. Total hysterectomy was described for severe hemorrhage cases [14]. Minimally invasive approaches have been described. This includes hysteroscopy for visualization the uterine cavity combined with removal and aspiration of the ectopic mass by abdominal ultrasound or laparoscopy [15,16]. Expectant management is rarely successful. Two cases were reported to have been successful pregnancies but had maternal morbidities such as hysterectomy, ligation of iliac artery and transfusion [7,17].
270
J Med Ultrasound 2008 • Vol 16 • No 4
The medical treatment mainly consists of methotraxate (MTX) either systemically or locally. A combined approach had limited systemic absorption by an ectopic pregnancy surrounded by a thick fibrous scar. This combined injection of MTX had succeeded in some cases with beta-hCG exceeding 10,000 mIU/ dL [3,7,11]. At least 6–8 weeks follow-up are needed for serial beta-hCG and ultrasound examination after MTX injection. A failure of systemic treatment by MTX causing persistent bleeding and hysterectomy was reported [18] or hysteroscopic resection in minor bleeding [19,20]. Embolization of uterine vessels may minimize such complications. An injection of MTX with or without another intragestational injection of potassium chloride for viable conceptus were used, and in combination of embolization or ligation of uterine or iliac artery [21–23]. Operative hysteroscopy and curettage are used for an early pregnancy not deeply implanted in the myometrium. Several reports describe the successful management of scar pregnancies by operative laparoscopy, all of them less than 10 gestational weeks [6]. Management of heterotopic cesarean scar pregnancy is an extreme challenge when the preservation of the concurrent intrauterine pregnancy is wanted. Three cases were performed by KCl injection or fine needle aspiration into the heterotopic cesarean scar pregnancy in IVF-ET twins with successful preservation of the intrauterine pregnancy [24–26]. A successful case of laparoscopic management intrauterine gestation to a term delivery after a heterotopic cesarean scar pregnancy was reported [27].
Conclusion Cesarean scar pregnancies are more commonly encountered in recent decade. Women who have had a history of previous cesarean section, and an early first trimester transvaginal ultrasound are advised to confirm the intrauterine location of the implantation site. Either surgical or combined systemic and intragestational MTX were successful in the treatment of these early unruptured cesarean scar pregnancies.
Scar Pregnancy
Acknowledgments We acknowledge Ms H C Liao for preparing this manuscript.
References 1. Fylstra DL. Ectopic pregnancy within a cesarean scar: a review. Obstet Gynecol Surv 2002;57:537–43. 2. Seow KM, Huang LW, Lin YH, et al. Cesarean scar pregnancy: issues in management. Ultrasound Obstet Gynecol 2004;23:247–53. 3. Rotas MA, Haberman S, Levgur M. Cesarean scar ectopic pregnancies: etiology, diagnosis, and management. Obstet Gynecol 2006;107:1373–81. 4. Jiao LZ, Zhao J, Wan XR, et al. Diagnosis and treatment of cesarean scar pregnancy. Chin Med Sci J 2008;23:10–5. 5. Ofili-Yebovi D, Ben-Nagi J, Sawyer E, et al. Deficient lower-segment cesarean section scars: prevalence and risk factors. Ultrasound Obstet Gynecol 2008;31:72–7. 6. Halperin R, Schneider D, Mendlovic S, et al. Uterinepreserving emergency surgery for cesarean scar pregnancies: another medical solution to an iatrogenic problem. Fertil Steril 2008; Apr 26. [Epub ahead of print] 7. Maymon R, Halperin R, Mendlovic S, et al. Ectopic pregnancies in caesarean section scars: the 8 year experience of one medical centre. Hum Reprod 2004;19:278–84. 8. Vial Y, Petignat P, Hohlfeld P. Pregnancy in a cesarean scar. Ultrasound Obstet Gynecol 2000;16:592–3. 9. Jurkovic D, Hillaby K, Woelfer B, et al. First-trimester diagnosis and management of pregnancies implanted into the lower uterine segment cesarean section scar. Ultrasound Obstet Gynecol 2003;21:220–7. 10. Nawroth F, Foth D, Wilhelm L, et al. Conservative treatment of ectopic pregnancy in a cesarean section scar with methotrexate: a case report. Eur J Obstet Gynecol Reprod Biol 2001;99:135–7. 11. Pascual MA, Hereter L, Graupera B, et al. Threedimensional power Doppler ultrasound diagnosis and conservative treatment of ectopic pregnancy in a cesarean section scar. Fertil Steril 2007;88:706 e5–7. 12. Teng HC, Kumar G, Ramli NM. A viable secondary intra-abdominal pregnancy resulting from rupture of uterine scar: role of MRI. Br J Radiol 2007;80:e134–6. 13. Rempen A, Albert P. [Diagnosis and therapy of an in the cesarean section scar implanted early pregnancy]. Z Geburtshilfe Perinatol 1990;194:46–8. 14. Larsen JV, Solomon MH. Pregnancy in a uterine scar sacculus—an unusual cause of postabortal haemorrhage. A case report. S Afr Med J 1978;53:142–3.
15. Lee CL, Wang CJ, Chao A, et al. Laparoscopic management of an ectopic pregnancy in a previous caesarean section scar. Hum Reprod 1999;14:1234–6. 16. Wang YL, Su TH, Chen HS. Operative laparoscopy for unruptured ectopic pregnancy in a caesarean scar. BJOG 2006;113:1035–8. 17. Herman A, Weinraub Z, Avrech O, et al. Follow up and outcome of isthmic pregnancy located in a previous caesarean section scar. Br J Obstet Gynaecol 1995;102: 839–41. 18. Lai YM, Lee JD, Lee CL, et al. An ectopic pregnancy embedded in the myometrium of a previous cesarean section scar. Acta Obstet Gynecol Scand 1995;74:573–6. 19. Chao A, Chao AS, Wang ST, et al. Mifepristoneinduced abortion in one horn and a growing fetus in another horn in a patient with a twin pregnancy in a bicornuate uterus. Fertil Steril 2006;86:1764 e3–5. 20. Ozkan S, Caliskan E, Ozeren S, et al. Three-dimensional ultrasonographic diagnosis and hysteroscopic management of a viable cesarean scar ectopic pregnancy. J Obstet Gynaecol Res 2007;33:873–7. 21. Yang MJ, Jeng MH. Combination of transarterial embolization of uterine arteries and conservative surgical treatment for pregnancy in a cesarean section scar. A report of 3 cases. J Reprod Med 2003;48:213–6. 22. Ghezzi F, Raio L, Mueller MD, et al. Vaginal extraction of pelvic masses following operative laparoscopy. Surg Endosc 2002;16:1691–6. 23. Hois EL, Hibbeln JF, Sclamberg JS. Spontaneous twin tubal ectopic gestation. J Clin Ultrasound 2006;34:352–5. 24. Salomon LJ, Fernandez H, Chauveaud A, et al. Successful management of a heterotopic caesarean scar pregnancy: potassium chloride injection with preservation of the intrauterine gestation: case report. Hum Reprod 2003;18:189–91. 25. Hsieh BC, Lin YH, Huang LW, et al. Cervical pregnancy after in vitro fertilization and embryo transfer successfully treated with methotrexate and intracervical injection of vasopressin. Acta Obstet Gynecol Scand 2004;83:112–4. 26. Wang CN, Chen CK, Wang HS, et al. Successful management of heterotopic cesarean scar pregnancy combined with intrauterine pregnancy after in vitro fertilization-embryo transfer. Fertil Steril 2007;88:706 e13–6. 27. Demirel LC, Bodur H, Selam B, et al. Laparoscopic management of heterotopic cesarean scar pregnancy with preservation of intrauterine gestation and delivery at term: case report. Fertil Steril 2008; Mar 17. [Epub ahead of print]
J Med Ultrasound 2008 • Vol 16 • No 4
271