Morphology, intrafetal vascular pattern, and umbilical artery Doppler indices of acardiac twins

Abstract

BackgroundTwin reversed arterial perfusion (TRAP) sequence consists of acardiac twin (A) paradoxically perfused by pump twin (P) through an umbilical artery (UA). We proposed characterization of acardiac twins with intrafetal vascular pattern (IVP), and assessed its correlation with morphology and UA Doppler indices.MethodsWe prospectively evaluated 21 cases of TRAP sequence. Morphology (acardia vs hemicardia) and IVP (simple vs complex) of acardiac twins were characterized with ultrasound and color Doppler. Twins weight ratio (A/P Wt) and UA Doppler indices of acardiac and pump twins including (1) difference of systolic/diastolic ratio (UA ∆S/D), (2) difference of resistance index (UA ∆RI), and (3) ratio of pulsatility index (UA PI A/P) were calculated.ResultsThe median (min, max) gestational age at diagnosis was 18 (11, 27) weeks. Acardia (n = 14) were associated with simple IVP (n = 16) (P < .05). After exclusion of acardia with complex IVP (n = 1), the A/P Wt, UA ∆S/D, UA ∆RI, and UA PI A/P of acardia with simple IVP (n = 13), hemicardia with simple IVP (n = 3), and hemicardia with complex IVP (n = 4) were not significantly different (P > .05).ConclusionsMost of acardiac twins were acardia with simple IVP. Morphology and IVP of acardiac twins were not associated with UA Doppler indices.

Síndrome da Acardia Fetal em gestação gemelar monozigótica: relato de caso

“…Além disso, a dopplervelocimetria pode ser útil na identificação da perfusão arterial reversa no feto acárdico e na caracterização de comunicações vasculares anormais presentes na placenta e no cordão umbilical. 20,21 No caso apresentado, com base nos dados obtidos na avaliação do…”

Doppler Waveform Analysis of Intertwin Venous Blood Flow in Twin Reversed Arterial Perfusion (TRAP) Sequence with a Rudimentary Heart

“…Intertwin hemodynamics have been investigated using the arterial Doppler (Shih et al, 1999;Wataganara et al, 2020), but not the venous Doppler waveform. Shih et al (1999) previously categorized the UA Doppler waveforms in TRAP sequences.…”

Twin Reversed Arterial Perfusion Sequence: Prenatal Diagnosis and Treatment

“…Two pathways have been proposed to explain the pathogenesis of the TRAP sequence, 11 including the aberrant placental vascular pattern during the early stages of monochorionic placentation and primary defect in cardiac embryogenesis because of chromosomal abnormality or environmental factors, when the unique perfusion of the acardiac fetus is received through anastomoses between the umbilical vessels. 3 Thus, when the acardiac twin receives deoxygenated blood from the pump twin. 12 The perinatal mortality rate of the pump twin is as high as 50% to 55%.…”

“…Twin reversed arterial perfusion (TRAP) sequence is a rare phenomenon characterized by the presence of an acardiac twin perfused by a structurally normal fetus (pump twin), occurring in 1% of monochorionic pregnancies and one in 35,000 in all pregnancies 1–3 . However, because of improved ultrasound diagnosis and the widespread use of assisted reproductive technologies in recent years, the incidence of TRAP has grown to 2.6% of monozygotic twins and one in every 9500 to 11,000 pregnancies 4,5 …”

“…Twin reversed arterial perfusion (TRAP) sequence is a rare phenomenon characterized by the presence of an acardiac twin perfused by a structurally normal fetus (pump twin), occurring in 1% of monochorionic pregnancies and one in 35,000 in all pregnancies. [1][2][3] However, because of improved ultrasound diagnosis and the widespread use of assisted reproductive technologies in recent years, the incidence of TRAP has grown to 2.6% of monozygotic twins and one in every 9500 to 11,000 pregnancies. 4,5 The fetal blood flow in the umbilical artery comes from the pump twin to the acardiac twin through artery-artery anastomosis on the placental surface, and this anatomical feature puts the pump fetus at risk of hyperdynamic circulation and high-output cardiac failure.…”