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Conjoined Twins
Anne M. 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

            • CT Findings

              • Ultrasonographic 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. Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
                                    2. 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
                                    3. Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
                                    4. Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
                                    5. Kobylarz K: Anaesthesia of conjoined twins. Anaesthesiol Intensive Ther. 46(2):124-9, 2014
                                    6. Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
                                    7. Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
                                    8. Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
                                    9. 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
                                    10. 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
                                    11. Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
                                    12. Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
                                    13. 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
                                    14. Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
                                    15. Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
                                    16. Wen X et al: Thoraco-omphalopagus conjoined twins: impact of ultrasound assessment on successful surgical separation. Clin Imaging. 37(1):138-42, 2013
                                    17. Singh Y et al: Early prenatal diagnosis in a case of conjoined twin with Craniopagus and Thoraco-omphalopagus. Med J Armed Forces India. 68(4):381-2, 2012
                                    18. Staffenberg DA et al: Separation of craniopagus conjoined twins with a staged approach. J Craniofac Surg. 23(7 Suppl 1):2004-10, 2012
                                    19. Saguil E et al: Conjoined twins in the Philippines: experience of a single institution. Pediatr Surg Int. 25(9):775-80, 2009
                                    20. Savona-Ventura C et al: Conjoint twinning in the Maltese Islands. J Obstet Gynaecol. 29(7):599-604, 2009
                                    21. Tihtonen K et al: Diamniotic omphalopagus conjoined twins in a diamniotic pregnancy. Fetal Diagn Ther. 25(3):343-5, 2009
                                    22. Karnak I et al: Minimally conjoined omphalopagi: emphasis on embryogenesis and possibility of emergency separation. Turk J Pediatr. 50(5):503-8, 2008
                                    23. Al Rabeeah A: Conjoined twins--past, present, and future. J Pediatr Surg. 41(5):1000-4, 2006
                                    24. Andrews RE et al: Echocardiographic assessment of conjoined twins. Heart. 92(3):382-7, 2006
                                    25. McMahon CJ et al: Congenital heart defects in conjoined twins: outcome after surgical separation of thoracopagus. Pediatr Cardiol. 27(1):1-12, 2006
                                    26. Votteler TP et al: Long-term results of 10 conjoined twin separations. J Pediatr Surg. 40(4):618-29, 2005
                                    27. Janik JS et al: Spectrum of anorectal anomalies in pygopagus twins. J Pediatr Surg. 38(4):608-12, 2003
                                    28. Mackenzie TC et al: The natural history of prenatally diagnosed conjoined twins. J Pediatr Surg. 37(3):303-9, 2002
                                    29. Kingston CA et al: Imaging in the preoperative assessment of conjoined twins. Radiographics. 21(5):1187-208, 2001
                                    30. Spielmann AL et al: MRI of conjoined twins illustrating advances in fetal imaging. J Comput Assist Tomogr. 25(1):88-90, 2001
                                    31. Spencer R: Anatomic description of conjoined twins: a plea for standardized terminology. J Pediatr Surg. 31(7):941-4, 1996
                                    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

                                              • CT Findings

                                                • Ultrasonographic 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. Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
                                                                      2. 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
                                                                      3. Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
                                                                      4. Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
                                                                      5. Kobylarz K: Anaesthesia of conjoined twins. Anaesthesiol Intensive Ther. 46(2):124-9, 2014
                                                                      6. Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
                                                                      7. Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
                                                                      8. Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
                                                                      9. 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
                                                                      10. 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
                                                                      11. Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
                                                                      12. Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
                                                                      13. 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
                                                                      14. Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
                                                                      15. Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
                                                                      16. Wen X et al: Thoraco-omphalopagus conjoined twins: impact of ultrasound assessment on successful surgical separation. Clin Imaging. 37(1):138-42, 2013
                                                                      17. Singh Y et al: Early prenatal diagnosis in a case of conjoined twin with Craniopagus and Thoraco-omphalopagus. Med J Armed Forces India. 68(4):381-2, 2012
                                                                      18. Staffenberg DA et al: Separation of craniopagus conjoined twins with a staged approach. J Craniofac Surg. 23(7 Suppl 1):2004-10, 2012
                                                                      19. Saguil E et al: Conjoined twins in the Philippines: experience of a single institution. Pediatr Surg Int. 25(9):775-80, 2009
                                                                      20. Savona-Ventura C et al: Conjoint twinning in the Maltese Islands. J Obstet Gynaecol. 29(7):599-604, 2009
                                                                      21. Tihtonen K et al: Diamniotic omphalopagus conjoined twins in a diamniotic pregnancy. Fetal Diagn Ther. 25(3):343-5, 2009
                                                                      22. Karnak I et al: Minimally conjoined omphalopagi: emphasis on embryogenesis and possibility of emergency separation. Turk J Pediatr. 50(5):503-8, 2008
                                                                      23. Al Rabeeah A: Conjoined twins--past, present, and future. J Pediatr Surg. 41(5):1000-4, 2006
                                                                      24. Andrews RE et al: Echocardiographic assessment of conjoined twins. Heart. 92(3):382-7, 2006
                                                                      25. McMahon CJ et al: Congenital heart defects in conjoined twins: outcome after surgical separation of thoracopagus. Pediatr Cardiol. 27(1):1-12, 2006
                                                                      26. Votteler TP et al: Long-term results of 10 conjoined twin separations. J Pediatr Surg. 40(4):618-29, 2005
                                                                      27. Janik JS et al: Spectrum of anorectal anomalies in pygopagus twins. J Pediatr Surg. 38(4):608-12, 2003
                                                                      28. Mackenzie TC et al: The natural history of prenatally diagnosed conjoined twins. J Pediatr Surg. 37(3):303-9, 2002
                                                                      29. Kingston CA et al: Imaging in the preoperative assessment of conjoined twins. Radiographics. 21(5):1187-208, 2001
                                                                      30. Spielmann AL et al: MRI of conjoined twins illustrating advances in fetal imaging. J Comput Assist Tomogr. 25(1):88-90, 2001
                                                                      31. Spencer R: Anatomic description of conjoined twins: a plea for standardized terminology. J Pediatr Surg. 31(7):941-4, 1996