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Background: Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic multiple gestation pregnancies, in which the pump twin provides hemodynamic support to a nonviable co-twin (acardius). Fetal magnetic resonance imaging (MRI) is used to detect pump twin abnormalities, particularly brain ischemia, prior to fetal intervention to interrupt umbilical blood flow to the acardius. Objective: To summarize the imaging findings of TRAP sequence pregnancies in a large series. Materials and methods: A single-center retrospective review was performed of all TRAP sequence pregnancies referred for fetal MRI (2004–2021). Fetal MRI, ultrasound, and echocardiography data were collected. Results: Eighty-eight TRAP sequence pregnancies with MRI were included (mean gestational age, 19.8±2.8 weeks). Demise of the pump twin was noted in two pregnancies at the time of MRI. By MRI, 12% (10/86) of live pump twins had abnormalities, including 3% (3/86) with brain abnormalities and 9% (8/86) with extra-cranial abnormalities. By echocardiography, 7% (6/86) of pump twins had structural cardiac abnormalities. Three acardius morphological subtypes were identified by MRI: acephalus (55%, 48/88), anceps (39%, 34/88), and amorphous (7%, 6/88). The mean ultrasound acardius to pump twin ratio A/P ratio, calculated for each twin pair as the ratio of the acardius trunk (and head, if present) plus limb volume to the pump twin estimated fetal weight) differed among the three acardius subtypes (P=.03). The mean A/P ratio moderately correlated with pump twin cardiothoracic ratio and combined cardiac output (Pearson's r=0.45 and 0.48, respectively, both P<.001). Conclusion: Fetal MRI of TRAP sequence pregnancies found anomalies in a substantial number of pump twins. The three acardius subtypes differed in A/P ratio, which moderately correlated with the pump twin cardiothoracic ratio and combined cardiac output. [ABSTRACT FROM AUTHOR]

Acardiac twin is a rare complication of monochorionic twin pregnancy. We present case of a 24 years-old primigravida with monochorionic pregnancy having an amorphous acardiac twin diagnosed during routine first trimester ultrasound scan. She was managed expectantly since there were no signs of hemodynamic compromise in the normal twin with close ultrasound fetal surveillance using gray scale and color Doppler ultrasound. Spontaneous regression of vascularity with reduced size of the acardiac twin was seen subsequently.

Twin reversed arterial perfusion syndrome is a rare obstetric condition that occurs in monochorionic twin pregnancies, resulting in coexistence of a normal “pump” twin and an acardiac twin. The acardiac twin is dependent upon the normal twin to provide circulation by means of vascular anastomosis, thereby putting the pump fetus at risk of high output cardiac failure. Overall only 50% of pump twins survive. Mortality for acardiac twin is 100%. We present a case of 26-year-old primigravida female presenting with 8 months of amenorrhea with unsure LMP. Ultrasonography followed by fetal MRI was carried out which revealed acardius acephalus twin with absence of blood flow in umbilical vessels. Pump twin had multicystic dysplastic left kidney with single umbilical artery. Following delivery, the pump twin survived well and the deformed fetus showed features of twin reversed arterial perfusion syndrome.

The TRAP sequence, also known as acardiac twinning is a rare complication that is unique to monochorioinic multiple pregnancies affecting 1% of monochorioinic pregnancies and about 1 in 35000 of all pregnancies. In TRAP, blood flows from the umbilical artery of the pump twin to the umbilical artery of the perfused twin through artery to artery (AA) anastomosis. The perfused twin has poor development of the upper extremities and the normal or pump twin is at risk of a poor perinatal outcome. This is a report of a patient with TRAP sequence diagnosed in the second trimester who was managed conservatively and had a good outcome for the normal twin.

Objective: To investigate twin reversed arterial perfusion (TRAP) sequence for the prediction of TRAP‐related adverse pregnancy outcomes at the gestational age of 11–14 weeks. Methods: Pregnant women in the first trimester diagnosed with TRAP were recruited at West China Second University Hospital from January 2015 to June 2018. Systematic screening for the pump twin's crown‐rump length (CRL) and acardiac twin's upper pole‐rump length (URL) was conducted using ultrasonic detection. The (CRL – URL)/CRL and URL/CRL ratios were used to assess the pregnancy outcomes for the pump twin. Twenty‐one pregnant women aged 21–39 years with a gestation of 11–14 weeks were recruited. Results: TRAP was diagnosed on average (± standard deviation (SD)) at pregnancy week 13.1 ± 0.18. The pump twins' mean (± SD) CRL was 6.65 ± 1.1 cm. The incidence of intrauterine death for the pump twins was 19.0% (n = 4), the miscarriage rate was 14.3% (n = 3), and the live birth rate was 66.7% (n = 14). The (CRL – URL)/CRL ratios between the nonsurvival (intrauterine death and miscarriage) and survival groups significantly differed (0.33 ± 0.08 vs. 0.58 ± 0.08, p < 0.05). Similarly, the URL/CRL ratios between the nonsurvival and survival groups significantly differed (0.67 ± 0.08 vs. 0.42 ± 0.08, p < 0.05). Conclusion: The (CRL – URL)/CRL and URL/CRL ratios were valuable indicators for determining pregnancy outcomes of pump twins with TRAP at an early gestational age. [ABSTRACT FROM AUTHOR]

TRAP sequence (twin reversed arterial perfusion) is a complication with a poor prognosis, seen only in monochorionic twin pregnancies, known as acardiac twin formation1. In the very early stages of the formation periods of twin pregnancies, as a result of the single formation of the placenta and the defective formation of the cord vessels of the second baby (acardiac twin), the heart and accordingly the brain development cannot occur in the baby with placenta abnormalities; but other parts of the body can develop in different combinations. Therefore, the second baby can develop from a separate creature to the other baby as a parasite. The normal twin, is known as the pump twin and provides the blood circulation of the acardiac twin. These inter twin anastomoses lead to circulatory confusion, the reverse circulatory morphogenesis interrupted and acardiac twinning occurs2. This case is presented because the patient had a healthy twin who was born due to the onset of preterm labor that was not terminated at the request of the family, and the other twin with acardiac anencephaly. Ablation treatment could not be performed due to the delay in our case, and the pump twin was delivered in a healthy way. [ABSTRACT FROM AUTHOR]

Annachiara Vitucci, Anna Fichera, Nicola Fratelli, Enrico Sartori, Federico Prefumo Division of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Brescia, ItalyCorrespondence: Federico PrefumoDivision of Obstetrics and Gynecology, ASST Spedali Civili, Department of Clinical and Experimental Sciences, University of Brescia, Piazzale Spedali Civili 1, Brescia 25123, ItalyTel +39 030 3995340Fax +39 030 3995034Email federico.prefumo@unibs.itAbstract: Twin reversed arterial perfusion (TRAP) sequence is a specific and severe complication of monochorionic multiple pregnancy, characterized by vascular anastomosis and partial or complete lack of cardiac development in one twin. Despite its rarity, interest in the international literature is rising, and we aimed to review its pathogenesis, prenatal diagnostic features and treatment options. Due to the parasitic hemodynamic dependence of the acardiac twin on the pump twin, the management of these pregnancies aims to maximize the pump twin’s chances of survival. If treatment is needed, the best timing of intervention is still debated, although the latest studies encourage intervention in the first trimester of pregnancy. As for the technique of choice to interrupt the vascular supply to the acardiac twin, ultrasound-guided laser coagulation and radiofrequency ablation of the intrafetal vessels are usually the preferred approaches.Keywords: TRAP sequence, acardiac twin, pump twin, clinical management, fetal therapy

The TRAP sequence, also known as acardiac twinning is a rare complication that is unique to monochorioinic multiple pregnancies affecting 1% of monochorioinic pregnancies and about 1 in 35000 of all pregnancies. In TRAP, blood flows from the umbilical artery of the pump twin to the umbilical artery of the perfused twin through artery to artery (AA) anastomosis. The perfused twin has poor development of the upper extremities and the normal or pump twin is at risk of a poor perinatal outcome. This is a report of a patient with TRAP sequence diagnosed in the second trimester who was managed conservatively and had a good outcome for the normal twin.

We performed a dual-gate Doppler examination for a twin reversed arterial perfusion (TRAP) sequence in a monochorionic-triamniotic triplet pregnancy at 16 weeks of gestation and were able to identify the pump twin by arterial pulse rate synchronicity. We performed radiofrequency ablation to coagulate blood flow in the acardius at 16 weeks of gestation without any postoperative complication. At 29 weeks of gestation, we performed a cesarean section due to preterm rupture of the membranes and the patient delivered 1167/1237-g female neonates and a macerated acardius. Examination of the placenta revealed two thickened vessels from the pump twin to the acardius, which had been prenatally identified by dual-gate Doppler. This new technology launches the new field of noninvasive fetal identification for triplet TRAP sequence. [ABSTRACT FROM AUTHOR]

TRAP (Twin Reversed Arterial Perfusion) sequence is a rare malformation that occurs in monozygotic twin pregnancies. Twin weight ratio in our case was 76% (body weight of pump twin was 1800 g, acardiac twin 1370 g), but in spite of that the pump twin had a mild clinical picture with premature birth, fetal hydrops (mild pleural effusion; hypoproteinemia; on the 3rd day of life the baby was without edema and the level of his serum proteins were in referral ranges) and mild myocardial hypertrophy of left ventricle (echocardiography performed on the 28th day of life was normal). [ABSTRACT FROM AUTHOR]

Synopsis: The present study reports a case of twin reversed arterial perfusion syndrome with spontaneous interruption of blood supply in the acardiac twin. [ABSTRACT FROM AUTHOR]

Acardiac parabiotic twinning, also known as a twin reversed arterial perfusion (TRAP) sequence, is a rare occurrence found only in monozygotic twin fetuses whose vascular systems are connected. The circulation of the acardiac twin is accomplished solely by the heart of the other fetus. Although antenatal diagnosis of the TRAP sequence has been reported by several authors, the pathogenesis remains controversial. This case was incidentally detected during routine antenatal sonographic examination at 29 weeks of gestation. [ABSTRACT FROM AUTHOR]

Acardiac twins are usually diagnosed during the antenatal period and almost invariably cause complications to the other fetus. In this case, an acardiac twin pregnancy was misdiagnosed antenatally as a degenerated myoma but ended with delivery of a healthy baby. [Copyright &y& Elsevier]