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
Omran A et al: Early separation of omphalopagus conjoined twins: a case report from Syria. J Surg Case Rep. 2020(1):rjz374, 2020
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
Wataganara T et al: Additional benefits of three-dimensional ultrasound for prenatal assessment of twins. J Perinat Med. 48(2):102-14, 2020
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
Willobee BA et al: Predictors of in-hospital mortality in newborn conjoined twins. Surgery. 166(5):854-60, 2019
C Sager E et al: Conjoined twins: pre-birth management, changes to NRP, and transport. Semin Perinatol. 42(6):321-8, 2018
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
Carreker C et al: Family support and media considerations with conjoined twins. Semin Perinatol. 42(6):393-401, 2018
Fallon SC et al: The surgical principles of conjoined twin separation. Semin Perinatol. 42(6):386-92, 2018
Mehollin-Ray AR: Prenatal and postnatal radiologic evaluation of conjoined twins. Semin Perinatol. 42(6):369-80, 2018
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
Thomas A et al: An ethically-justifiable, practical approach to decision-making surrounding conjoined-twin separation. Semin Perinatol. 42(6):381-5, 2018
Mian A et al: Conjoined twins: from conception to separation, a review. Clin Anat. 30(3):385-96, 2017
Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
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
Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
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
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
Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
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
Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
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
Omran A et al: Early separation of omphalopagus conjoined twins: a case report from Syria. J Surg Case Rep. 2020(1):rjz374, 2020
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
Wataganara T et al: Additional benefits of three-dimensional ultrasound for prenatal assessment of twins. J Perinat Med. 48(2):102-14, 2020
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
Willobee BA et al: Predictors of in-hospital mortality in newborn conjoined twins. Surgery. 166(5):854-60, 2019
C Sager E et al: Conjoined twins: pre-birth management, changes to NRP, and transport. Semin Perinatol. 42(6):321-8, 2018
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
Carreker C et al: Family support and media considerations with conjoined twins. Semin Perinatol. 42(6):393-401, 2018
Fallon SC et al: The surgical principles of conjoined twin separation. Semin Perinatol. 42(6):386-92, 2018
Mehollin-Ray AR: Prenatal and postnatal radiologic evaluation of conjoined twins. Semin Perinatol. 42(6):369-80, 2018
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
Thomas A et al: An ethically-justifiable, practical approach to decision-making surrounding conjoined-twin separation. Semin Perinatol. 42(6):381-5, 2018
Mian A et al: Conjoined twins: from conception to separation, a review. Clin Anat. 30(3):385-96, 2017
Alkhateeb M et al: Early prenatal diagnosis of thoracopagus twins by ultrasound. Acta Inform Med. 23(1):60-2, 2015
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
Stahr N et al: In utero and postnatal imaging findings of parasitic conjoined twins (ischiopagus parasiticus tetrapus). Pediatr Radiol. 45(5):767-70, 2015
Burans C et al: 3-dimensional ultrasound assisted counseling for conjoined twins. J Genet Couns. 23(1):29-32, 2014
Sanhal CY et al: Prenatal diagnosis of total type 1 vertical craniopagus with 3-dimensional sonography. J Ultrasound Med. 33(1):179-81, 2014
Wu Y et al: Fetal echocardiographic characteristics of fused heart in thoracopagus conjoined twins. Echocardiography. 31(7):E218-21, 2014
Aneja A et al: Conjoined twins: a rare case of thoraco-omphalopagus. J Clin Diagn Res. 7(7):1471-2, 2013
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
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
Lopes LM et al: Twenty-five years of fetal echocardiography in conjoined twins: lessons learned. J Am Soc Echocardiogr. 26(5):530-8, 2013
Prasanna LC et al: Double headed conjoined twin--autopsy findings. Indian J Med Res. 137(1):219, 2013
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
Tannuri AC et al: Conjoined twins: twenty years' experience at a reference center in Brazil. Clinics (Sao Paulo). 68(3):371-7, 2013
Terata M et al: Prenatal diagnosis of parasitic conjoined twins with three-dimensional ultrasound. Congenit Anom (Kyoto). 53(3):131-3, 2013
Wen X et al: Thoraco-omphalopagus conjoined twins: impact of ultrasound assessment on successful surgical separation. Clin Imaging. 37(1):138-42, 2013
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