Anomalous twin (TRAP twin) perfused by deoxygenated blood from pump twin
Blood enters TRAP fetus via umbilical artery (UA)
Reversed perfusion → selective development of torso/lower extremities
Lack of umbilical vein flow into heart → impaired/absent cardiac development
IMAGING
General Features
Ultrasonographic Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Image Interpretation Pearls
Selected References
Gabby LC et al: Risk factors for co-twin fetal demise following radiofrequency ablation in multifetal monochorionic gestations. Fetal Diagn Ther. 1-7, 2020
Shanahan MA et al: Placental anatomy and function in twin gestations. Obstet Gynecol Clin North Am. 47(1):99-116, 2020
Shettikeri A et al: Outcome of pregnancies diagnosed with TRAP sequence prenatally: a single-centre experience. Fetal Diagn Ther. 47(4):301-6, 2020
Tavares de Sousa M et al: First-trimester intervention in twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol. 55(1):47-9, 2020
Ting YH et al: Outcomes of radiofrequency ablation for selective fetal reduction in complicated monochorionic pregnancies performed before 16 gestational weeks and thereafter. Ultrasound Obstet Gynecol. ePub, 2020
Jha P et al: US Evaluation of twin pregnancies: Importance of chorionicity and amnionicity. Radiographics. 39(7):2146-66, 2019
Expert Panel on Women's Imaging:. et al: ACR Appropriateness Criteria® multiple gestations. J Am Coll Radiol. 14(11S):S476-89, 2017
Roethlisberger M et al: First-trimester intervention in twin reversed arterial perfusion sequence: does size matter? Ultrasound Obstet Gynecol. 50(1):40-4, 2017
Mone F et al: Intervention versus a conservative approach in the management of TRAP sequence: a systematic review. J Perinat Med. 44(6):619-29, 2016
Sugibayashi R et al: Forty cases of twin reversed arterial perfusion sequence treated with radio frequency ablation using the multistep coagulation method: a single-center experience. Prenat Diagn. 36(5):437-43, 2016
van Gemert MJ et al: Acardiac twin pregnancies part III: model simulations. Birth Defects Res A Clin Mol Teratol. 106(12):1008-15, 2016
van Gemert MJ et al: Hypothesis acardiac twin pregnancies: pathophysiology-based hypotheses suggest risk prediction by pump/acardiac umbilical venous diameter ratios. Birth Defects Res A Clin Mol Teratol. 106(2):114-21, 2016
Stephenson CD et al: Microwave ablation for twin-reversed arterial perfusion sequence: a novel application of technology. Fetal Diagn Ther. 38(1):35-40, 2015
Takano M et al: Experience of fetoscopic laser photocoagulation and cord transection for twin-reversed arterial perfusion sequence. J Obstet Gynaecol Res. 41(9):1326-9, 2015
van Gemert MJ et al: Twin reversed arterial perfusion sequence is more common than generally accepted. Birth Defects Res A Clin Mol Teratol. 103(7):641-3, 2015
Berg C et al: Twin reversed arterial perfusion (TRAP) sequence--does monoamniocity preclude early intervention? Ultrasound Obstet Gynecol. 44(2):241-2, 2014
Chaveeva P et al: Optimal method and timing of intrauterine intervention in twin reversed arterial perfusion sequence: case study and meta-analysis. Fetal Diagn Ther. 35(4):267-79, 2014
Peeters SH et al: Fetal surgery in complicated monoamniotic pregnancies: case series and systematic review of the literature. Prenat Diagn. 34(6):586-91, 2014
Prefumo F et al: Fetoscopic cord transection for treatment of monoamniotic twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol. 43(2):234-5, 2014
Oliver ER et al: Twin reversed arterial perfusion sequence: a new method of parabiotic twin mass estimation correlated with pump twin compromise. J Ultrasound Med. 32(12):2115-23, 2013
Related Anatomy
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References
Tables
Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Abbreviations
Twin reversed arterial perfusion (TRAP)
Synonyms
Acardiac monster
Cardiac regression sequence
Definitions
Anomalous twin (TRAP twin) perfused by deoxygenated blood from pump twin
Blood enters TRAP fetus via umbilical artery (UA)
Reversed perfusion → selective development of torso/lower extremities
Lack of umbilical vein flow into heart → impaired/absent cardiac development
IMAGING
General Features
Ultrasonographic Findings
MR Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Staging, Grading, & Classification
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Image Interpretation Pearls
Selected References
Gabby LC et al: Risk factors for co-twin fetal demise following radiofrequency ablation in multifetal monochorionic gestations. Fetal Diagn Ther. 1-7, 2020
Shanahan MA et al: Placental anatomy and function in twin gestations. Obstet Gynecol Clin North Am. 47(1):99-116, 2020
Shettikeri A et al: Outcome of pregnancies diagnosed with TRAP sequence prenatally: a single-centre experience. Fetal Diagn Ther. 47(4):301-6, 2020
Tavares de Sousa M et al: First-trimester intervention in twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol. 55(1):47-9, 2020
Ting YH et al: Outcomes of radiofrequency ablation for selective fetal reduction in complicated monochorionic pregnancies performed before 16 gestational weeks and thereafter. Ultrasound Obstet Gynecol. ePub, 2020
Jha P et al: US Evaluation of twin pregnancies: Importance of chorionicity and amnionicity. Radiographics. 39(7):2146-66, 2019
Expert Panel on Women's Imaging:. et al: ACR Appropriateness Criteria® multiple gestations. J Am Coll Radiol. 14(11S):S476-89, 2017
Roethlisberger M et al: First-trimester intervention in twin reversed arterial perfusion sequence: does size matter? Ultrasound Obstet Gynecol. 50(1):40-4, 2017
Mone F et al: Intervention versus a conservative approach in the management of TRAP sequence: a systematic review. J Perinat Med. 44(6):619-29, 2016
Sugibayashi R et al: Forty cases of twin reversed arterial perfusion sequence treated with radio frequency ablation using the multistep coagulation method: a single-center experience. Prenat Diagn. 36(5):437-43, 2016
van Gemert MJ et al: Acardiac twin pregnancies part III: model simulations. Birth Defects Res A Clin Mol Teratol. 106(12):1008-15, 2016
van Gemert MJ et al: Hypothesis acardiac twin pregnancies: pathophysiology-based hypotheses suggest risk prediction by pump/acardiac umbilical venous diameter ratios. Birth Defects Res A Clin Mol Teratol. 106(2):114-21, 2016
Stephenson CD et al: Microwave ablation for twin-reversed arterial perfusion sequence: a novel application of technology. Fetal Diagn Ther. 38(1):35-40, 2015
Takano M et al: Experience of fetoscopic laser photocoagulation and cord transection for twin-reversed arterial perfusion sequence. J Obstet Gynaecol Res. 41(9):1326-9, 2015
van Gemert MJ et al: Twin reversed arterial perfusion sequence is more common than generally accepted. Birth Defects Res A Clin Mol Teratol. 103(7):641-3, 2015
Berg C et al: Twin reversed arterial perfusion (TRAP) sequence--does monoamniocity preclude early intervention? Ultrasound Obstet Gynecol. 44(2):241-2, 2014
Chaveeva P et al: Optimal method and timing of intrauterine intervention in twin reversed arterial perfusion sequence: case study and meta-analysis. Fetal Diagn Ther. 35(4):267-79, 2014
Peeters SH et al: Fetal surgery in complicated monoamniotic pregnancies: case series and systematic review of the literature. Prenat Diagn. 34(6):586-91, 2014
Prefumo F et al: Fetoscopic cord transection for treatment of monoamniotic twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol. 43(2):234-5, 2014
Oliver ER et al: Twin reversed arterial perfusion sequence: a new method of parabiotic twin mass estimation correlated with pump twin compromise. J Ultrasound Med. 32(12):2115-23, 2013
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