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Obstetrics
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Multiple Gestations
Conjoined Twins
Conjoined Twins
Anne Kennedy, MD
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KEY FACTS

  • Terminology

    • Imaging

      • Clinical Issues

        • Diagnostic Checklist

          TERMINOLOGY

          • Synonyms

            • Siamese twins
              • 1st Siamese twins "exhibited" in America in 1829
                • Chang and Eng born in Thailand, came to USA at age 18
                • Lived long and productive lives despite being conjoined

          • Definitions

            • Fetal fusion of variable degree
            • Nomenclature
              • Site of fusion + suffix "pagus"
                • Thoracopagus: Fused at chest, heart involved
                • Omphalopagus: Fused xiphoid to umbilicus, heart not involved
                • Pygopagus: Fused at buttocks
                • Ischiopagus: Fused at hips
                • Craniopagus: Fused at cranial level
              • Prefix "di" denotes separate parts associated with conglomerate structures
                • Dicephalus: Conglomerate mass with 2 identifiable heads
                • Diprosopus: Conglomerate skull vault with 2 faces, variable number of extremities
                • Janiceps: Synonym for diprosopus

          IMAGING

          • General Features

            • Ultrasonographic Findings

              • CT Findings

                • Imaging Recommendations

                  DIFFERENTIAL DIAGNOSIS

                    PATHOLOGY

                    • General Features

                      • Staging, Grading, & Classification

                        CLINICAL ISSUES

                        • Presentation

                          • Demographics

                            • Natural History & Prognosis

                              • Treatment

                                DIAGNOSTIC CHECKLIST

                                • Consider

                                  • Image Interpretation Pearls

                                    Selected References

                                    1. Omran A et al: Early separation of omphalopagus conjoined twins: a case report from Syria. J Surg Case Rep. 2020(1):rjz374, 2020
                                    2. Pang H et al: Prenatal diagnosis of parasitic conjoined twins using three-dimensional ultrasound: a case report. Int J Gynaecol Obstet. 148(2):265-66, 2020
                                    3. Wataganara T et al: Additional benefits of three-dimensional ultrasound for prenatal assessment of twins. J Perinat Med. 48(2):102-14, 2020
                                    4. Juhnke B et al: Use of virtual reality for pre-surgical planning in separation of conjoined twins:  a case report. Proc Inst Mech Eng H. 233(12):1327-32, 2019
                                    5. Willobee BA et al: Predictors of in-hospital mortality in newborn conjoined twins. Surgery. 166(5):854-60, 2019
                                    6. C Sager E et al: Conjoined twins: pre-birth management, changes to NRP, and transport. Semin Perinatol. 42(6):321-8, 2018
                                    7. Carlson TL et al: Successful separation of conjoined twins: the contemporary experience and historic review in Memphis. Ann Plast Surg. 80(6S Suppl 6):S333-9, 2018
                                    8. Carreker C et al: Family support and media considerations with conjoined twins. Semin Perinatol. 42(6):393-401, 2018
                                    9. Fallon SC et al: The surgical principles of conjoined twin separation. Semin Perinatol. 42(6):386-92, 2018
                                    10. Mehollin-Ray AR: Prenatal and postnatal radiologic evaluation of conjoined twins. Semin Perinatol. 42(6):369-80, 2018
                                    11. Parmekar S et al: Role of simulation in preparation for the care of conjoined twins-prenatal preparation to separation. Semin Perinatol. 42(6):329-39, 2018
                                    12. Thomas A et al: An ethically-justifiable, practical approach to decision-making surrounding conjoined-twin separation. Semin Perinatol. 42(6):381-5, 2018
                                    13. Mian A et al: Conjoined twins: from conception to separation, a review. Clin Anat. 30(3):385-96, 2017
                                    14. Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
                                    15. Sinha M et al: Assisted breech vaginal delivery of dicephalus dipus dibrachius conjoined twins: a case report. J Reprod Med. 60(3-4):160-4, 2015
                                    16. Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
                                    17. Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
                                    18. Kobylarz K: Anaesthesia of conjoined twins. Anaesthesiol Intensive Ther. 46(2):124-9, 2014
                                    19. Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
                                    20. Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
                                    21. Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
                                    22. Baken L et al: Diagnostic techniques and criteria for first-trimester conjoined twin documentation: a review of the literature illustrated by three recent cases. Obstet Gynecol Surv. 68(11):743-52, 2013
                                    23. Hirokazu T et al: Separation surgery of pygopagus asymmetrical conjoined twins sharing U-shaped spinal cord: case report and literature review. Childs Nerv Syst. 29(4):699-706, 2013
                                    24. Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
                                    25. Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
                                    26. Rhodes JL et al: Preoperative planning for the separation of omphalopagus conjoined twins-the role of a multicomponent medical model. J Craniofac Surg. 24(1):175-7, 2013
                                    27. Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
                                    28. Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
                                    29. Wen X et al: Thoraco-omphalopagus conjoined twins: impact of ultrasound assessment on successful surgical separation. Clin Imaging. 37(1):138-42, 2013
                                    Related Anatomy
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                                    Related Differential Diagnoses
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                                    References
                                    Tables

                                    Tables

                                    KEY FACTS

                                    • Terminology

                                      • Imaging

                                        • Clinical Issues

                                          • Diagnostic Checklist

                                            TERMINOLOGY

                                            • Synonyms

                                              • Siamese twins
                                                • 1st Siamese twins "exhibited" in America in 1829
                                                  • Chang and Eng born in Thailand, came to USA at age 18
                                                  • Lived long and productive lives despite being conjoined

                                            • Definitions

                                              • Fetal fusion of variable degree
                                              • Nomenclature
                                                • Site of fusion + suffix "pagus"
                                                  • Thoracopagus: Fused at chest, heart involved
                                                  • Omphalopagus: Fused xiphoid to umbilicus, heart not involved
                                                  • Pygopagus: Fused at buttocks
                                                  • Ischiopagus: Fused at hips
                                                  • Craniopagus: Fused at cranial level
                                                • Prefix "di" denotes separate parts associated with conglomerate structures
                                                  • Dicephalus: Conglomerate mass with 2 identifiable heads
                                                  • Diprosopus: Conglomerate skull vault with 2 faces, variable number of extremities
                                                  • Janiceps: Synonym for diprosopus

                                            IMAGING

                                            • General Features

                                              • Ultrasonographic Findings

                                                • CT Findings

                                                  • Imaging Recommendations

                                                    DIFFERENTIAL DIAGNOSIS

                                                      PATHOLOGY

                                                      • General Features

                                                        • Staging, Grading, & Classification

                                                          CLINICAL ISSUES

                                                          • Presentation

                                                            • Demographics

                                                              • Natural History & Prognosis

                                                                • Treatment

                                                                  DIAGNOSTIC CHECKLIST

                                                                  • Consider

                                                                    • Image Interpretation Pearls

                                                                      Selected References

                                                                      1. Omran A et al: Early separation of omphalopagus conjoined twins: a case report from Syria. J Surg Case Rep. 2020(1):rjz374, 2020
                                                                      2. Pang H et al: Prenatal diagnosis of parasitic conjoined twins using three-dimensional ultrasound: a case report. Int J Gynaecol Obstet. 148(2):265-66, 2020
                                                                      3. Wataganara T et al: Additional benefits of three-dimensional ultrasound for prenatal assessment of twins. J Perinat Med. 48(2):102-14, 2020
                                                                      4. Juhnke B et al: Use of virtual reality for pre-surgical planning in separation of conjoined twins:  a case report. Proc Inst Mech Eng H. 233(12):1327-32, 2019
                                                                      5. Willobee BA et al: Predictors of in-hospital mortality in newborn conjoined twins. Surgery. 166(5):854-60, 2019
                                                                      6. C Sager E et al: Conjoined twins: pre-birth management, changes to NRP, and transport. Semin Perinatol. 42(6):321-8, 2018
                                                                      7. Carlson TL et al: Successful separation of conjoined twins: the contemporary experience and historic review in Memphis. Ann Plast Surg. 80(6S Suppl 6):S333-9, 2018
                                                                      8. Carreker C et al: Family support and media considerations with conjoined twins. Semin Perinatol. 42(6):393-401, 2018
                                                                      9. Fallon SC et al: The surgical principles of conjoined twin separation. Semin Perinatol. 42(6):386-92, 2018
                                                                      10. Mehollin-Ray AR: Prenatal and postnatal radiologic evaluation of conjoined twins. Semin Perinatol. 42(6):369-80, 2018
                                                                      11. Parmekar S et al: Role of simulation in preparation for the care of conjoined twins-prenatal preparation to separation. Semin Perinatol. 42(6):329-39, 2018
                                                                      12. Thomas A et al: An ethically-justifiable, practical approach to decision-making surrounding conjoined-twin separation. Semin Perinatol. 42(6):381-5, 2018
                                                                      13. Mian A et al: Conjoined twins: from conception to separation, a review. Clin Anat. 30(3):385-96, 2017
                                                                      14. Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
                                                                      15. Sinha M et al: Assisted breech vaginal delivery of dicephalus dipus dibrachius conjoined twins: a case report. J Reprod Med. 60(3-4):160-4, 2015
                                                                      16. Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
                                                                      17. Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
                                                                      18. Kobylarz K: Anaesthesia of conjoined twins. Anaesthesiol Intensive Ther. 46(2):124-9, 2014
                                                                      19. Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
                                                                      20. Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
                                                                      21. Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
                                                                      22. Baken L et al: Diagnostic techniques and criteria for first-trimester conjoined twin documentation: a review of the literature illustrated by three recent cases. Obstet Gynecol Surv. 68(11):743-52, 2013
                                                                      23. Hirokazu T et al: Separation surgery of pygopagus asymmetrical conjoined twins sharing U-shaped spinal cord: case report and literature review. Childs Nerv Syst. 29(4):699-706, 2013
                                                                      24. Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
                                                                      25. Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
                                                                      26. Rhodes JL et al: Preoperative planning for the separation of omphalopagus conjoined twins-the role of a multicomponent medical model. J Craniofac Surg. 24(1):175-7, 2013
                                                                      27. Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
                                                                      28. Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
                                                                      29. Wen X et al: Thoraco-omphalopagus conjoined twins: impact of ultrasound assessment on successful surgical separation. Clin Imaging. 37(1):138-42, 2013