Pump Twin Research Articles

TWIN REVERSED ARTERIAL PERFUSION SEQUENCE (TRAP);

Twin reversed arterial perfusion sequence (TRAP sequence) is a condition thatoccurs only in identical twins that share a placenta (monochorionic), in which one twin lackinga functioning cardiac system “acardiac monster” receives blood from the normally developingtwin called the “pump twin”. This places an enormous demand on the heart putting the pumptwin at risk for cardiac failure. Left untreated, the pump twin will die in 50 percent to 75 percentof cases. Here we present the case report of a 20 years old G2P1at 32 weeks POG with amonochorionic twin pregnancy. One of the twins was “acardiac acephalous” and the other a“pump twin” with mild hydrocephalous.

First-trimester intervention in twin reversed arterial perfusion sequence: does size matter?

To evaluate the outcome of first-trimester intervention (12 + 0 to 14 + 0 weeks of gestation) in pregnancies complicated by twin reversed arterial perfusion (TRAP) sequence. All monochorionic diamniotic twin pregnancies diagnosed with TRAP sequence that underwent intrafetal laser ablation (IFL) of the feeding vessels before 14 + 0 weeks of gestation at the University of Bonn between 2010 and 2015 were analyzed retrospectively for intrauterine course and outcome. In the study period, 12 pregnancies with TRAP sequence were treated by IFL. Median gestational age at intervention was 13.2 (interquartile range (IQR), 12.6-13.6) weeks. In all cases, one intervention sufficed to disrupt the perfusion of the TRAP twin. There was no case of miscarriage, preterm prelabor rupture of membranes or hemorrhage. In five (41.7%) pregnancies, intrauterine death of the pump twin occurred at a median of 72.0 (IQR, 54.0-90.0; range, 48-96) h after intervention. The remaining seven pregnancies continued uneventfully resulting in birth of a healthy infant at term. A comparison of survivors and non-survivors identified a significant difference in median discordance between crown-rump length (CRL) of the pump twin and upper pole-rump length (URL) of the TRAP twin ((CRL - URL)/CRL ratio, 0.56 vs 0.31; P < 0.05 and URL/CRL ratio, 0.44 vs 0.68; P < 0.05). Survivors were treated at a significantly later gestational age than were non-survivors (median, 13.4 (IQR, 12.9-14.1) vs 12.6 (IQR, 12.5-13.1); P < 0.05). However, none of these parameters independently predicted survival. Although technically feasible, IFL performed in the first trimester for TRAP sequence is associated with a significant fetal loss rate. Gestational age at intervention, (CRL - URL)/CRL ratio and URL/CRL ratio are potential predictors of pregnancy outcome. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

A case report of twin reversed arterial perfusion sequence with expectant management

Acardiac twin or TRAP (twin reversed arterial perfusion) sequence is a rare complication of monochorionic pregnancies. In these cases, the heart is either absent or non-functional. It’s controversial whether conservative management or therapeutic treatment is better in TRAP-sequence. In this case, we present a 19-years old, primigravida diagnosed with spontaneous monochorionic monoamniotic twin pregnancy at 7th week of gestation. One of the fetuses had a crown-rump length of 8 mm and fetal heart rate 122/minute while the other one had a crown-rump of 7 mm with no detected fetal heartbeat. At the 11th week of gestation, the acardiac twin continued growing despite the absence of the fetal heart beat and fetal extremities. The cranium could not be evaluated clearly. The diagnosis of TRAP sequence was confirmed by the reversed direction of flow observed in the umbilical artery. Since the patient and her husband did not want any intervention, no interventional diagnostic and treatment modalities were applied. Preterm labor started at the 32th week. Because the presentations were transverse and breech, pump and acardiac fetus, respectively, a cesarean delivery was performed. A healthy female baby, weighing 1650 gr with APGAR scores of 9-10, first and fifth minutes, respectively, was delivered along with the acardiac fetus which was 1550 gram in weight, fetal heart beat negative, with upper and lower extremity deformities. The uniqueness of the present case is that there was no significant difference in the weight of both twins. The acardiac twin was as large as the pump twin. Except for twenty days hospitalization because of neonatal respiratory distress syndrome, which was a consequence of preterm labor, there were no problems with the pump twin even though managed conservatively. In monochorionic twin pregnancies, when one of the twins is found to be fetal heartbeat negative and it continues to grow with concomitant structural abnormalities, the TRAP sequence should come to mind. If the acardiac fetus is small and the pump fetus has no complications, the conservative approach can be considered. Our goal should be to deliver the pump twin with minimal complications. To achieve this, follow-ups and treatment should be individualized for each patient, the pump fetus should be monitored closely.

Misdiagnosis of an Acardiac Twin in the First Trimester, A Case Report.

Background: Twin reversed arterial perfusion (TRAP) sequence is a rare monochorionic twin pregnancy complication. It should be suspected in the first trimester ultrasound, when one fetus has no cardiac activity in a monochorionic pregnancies. Doppler study is essential for early diagnosis of acardiac twin. This manuscrips shows the importance of reassessing cases considered as vanishing twins in early pregnancy, to avoid a late diagnosis of acardiac twin, without timely treatment. Case Summary: In this case, the assumption of death of one fetus in the first trimester, delayed the correct diagnosis of TRAP until 25 weeks, when the case was referred to our unit. We opted conservative management with weekly ultrasound surveillance, looking for features of heart failure in the pump twin. After suspecting fetal anemia, at 32 weeks a healthy baby weighing 2100g was delivered along with a acardiac anceps with 518g. This is a case of expectant management, for lack of another option, with a successful end. Conclusion: Despite twin reversed arterial perfusion (TRAP) sequence being a rare monochorionic twin pregnancies complication, it should be suspected in the first trimester ultrasound, when detected a monochorionic pregnancies and one embryo/fetus has no cardiac activity. Follow up in fetal death of one twin in a monochorionic pregnancies must be done with Doppler to look for acardiac twin. Because pump twin may develop a high-output cardiac failure and intrauterine fetal demise, for continuing pregnancies without poor prognostic criteria, it is important to maintain weekly ultrasound surveillance, with attention to the intervention criterias.

Twin reversed arterial perfusion syndrome in a monochorionic monoamniotic twin pregnancy.

Yapıcıoğlu-Yıldızdaş H, Ece Ü, Sucu M, Yurdakul G, Şimşek H, Özlü F. Twin reversed arterial perfusion syndrome in a monochorionic monoamniotic twin pregnancy. Turk J Pediatr 2017; 59: 724-727. Twin reversed arterial perfusion syndrome is mostly seen in monochorionic diamniotic twin pregnancies with an estimated incidence of 1/9500-11000 pregnancies. One of the twins is acardiac with various abnormalities especially with upper part of the body, and mortality is 100%. The other twin functions as a pump twin and mostly has polyhydramnios and heart failure; and mortality rate is high due to prematurity and heart failure. Herein we report a TRAP syndrome and the prognosis of pump twin who was born at 30 weeks gestational age.

Study on the ultrasonic imaging characteristics of the twin reversed arterial perfusion sequence-hemiacardius

Objective To explore the ultrasonic characteristics of the twin reversed arterial perfusion (TRAP) sequence-hemiacardius. Methods A retrospective analysis of the clinical data and ultrasonic characteristics of 9 cases with the TRAP was made, which were compared with the pathlogical result after delivery. Results The prenatal ultrasonic imaging characteristics showed: The vestigial heart′s pulsating was seen in all the hemiacardius twin′s thoracic cavity, and the Doppler spectrum in it went up and down.It was noted that the heart rate was slower in the better (multicavity) development of the heart and faster in the poor development (pipe type and single cavity) of the heart. Nine hemiacardius twin had hydroderma and cystic hygroma. The head, spine, abdominal organs (both kindenys and intestines) of all the 9 cases were hypogenetic. The diaphragm was present in 7 cases; lower limbs was present in 8 cases, single leg was seen in one case; upper limbs was present in 7 cases. Seven cases of the pump twin suffered from the cardiac insufficiency. Polyhydramnios were seen in 5 cases. Prognosis of the 9 cases of the TRAP pump twin: the cessation of blood flow spontaneous was seen in one case, the pump twin was survived and delivered at term. Eight cases were demise(2 cases with intrauterine demise, 5 cases induced labor with cardiac insufficiency, 1 case died from polyhydramnios after premature birth). Conclusions The pump twin of the TRAP hemiacardiacs have a poor prognosis with the nautural course, and are easy to suffer from the cardiac insufficiency in utero. The ultrasonography can diagnose the TRAP hemiacardius accurately, which can be used to guide the clinical doctors to choose a reasonable timing to take intrauterine treatment, that will effectively improve the survival rate of the pump twin. Key words: Ultrasonography; Twin reversed arterial perfusion sequence; Hemiacardius; Acardiac

Uncommon complications of monochorionic twin pregnancies: Twin reversed arterial perfusion sequence.

Twin reversed arterial perfusion (TRAP) sequence occurs when there is one non-viable twin without cardiac structures and a viable pump twin that perfuses the acardiac mass. This study aims to investigate the management and immediate neonatal outcomes for monochorionic multiple pregnancies complicated by TRAP referred to the NSW Fetal Therapy Centre (NSW FTC). Retrospective cohort study of multiple pregnancies referred to NSW FTC between April 2006 and April 2014, reviewing data for cases of TRAP sequence (n = 19, including two triplet cases) compared to a timeframe matched sample of uncomplicated monochorionic diamniotic (MCDA) twin pregnancies managed in the unit (n = 45). Primary management of the 19 TRAP cases was expectant management in 10 (53%), radiofrequency ablation (RFA) in 6 (32%), and bipolar cord coagulation, amniodrainage and termination of pregnancy in 1 case each. 1 of 6 RFA cases had pump twin demise <1 week post-procedure. Average gestation at birth (35.1 ± 5.0 vs. 35.0 ± 2.8 weeks) and mean birthweight (2157 ± 1019 g vs. 2245 ± 537 g) were similar between TRAP pump fetuses and uncomplicated MCDA cases. Pump twin survival was 81% (twins only) compared to 98% for uncomplicated MCDA twins (P = 0.02), and in 5 of 19 (26%) TRAP pregnancies the pump fetus had a congenital anomaly. Mean gestational age at birth and mean birthweight were similar for both TRAP and uncomplicated MCDA pregnancies. TRAP cases, however, had higher perinatal mortality, and high rates of congenital anomaly. The overall neonatal outcome at NSW FTC for TRAP cases is similar to reported international outcomes.

Acardiac twin pregnancies part III: Model simulations.

Acardiac monochorionic twins lack cardiac function but grow by passive perfusion of the pump twin's deoxygenated arterial blood through placental arterioarterial (AA) and venovenous (VV) anastomoses and by hypoxia-mediated neovascularization. Pump twins therefore must continuously increase their cardiac output which may cause heart failure. Our aims were: to adapt our twin-twin transfusion syndrome model for acardiac twin pregnancies, to simulate pump and acardiac twin development, and to examine the model for early prognostic markers of pump twin survival. We used an infinite acardiac placental resistance, based on placental dye injection studies and simulations, suggesting the AA-Acardiac-VV series resistance determines the pump twin's excess cardiac output. Pump and acardiac development were expressed by the pump's excess cardiac output versus its normal value, represented by pump/acardiac umbilical venous diameter (UVD) ratios. UVD ratios distinguish between AA-VV anastomoses that do and do not cause hydropic pump twins. Pump twins can handle relative larger acardiac perfusion at later than earlier gestation. Both VV and acardiac resistances are significantly smaller than the AA resistance, based on respectively clinical data and acardiac blood volumetric growth. Our simulations support clinical results which show that UVD ratios aid in the prediction of pump twin risk. The AA anastomosis controls the future of both the pump and the acardiac. Correlation between acardiac size and pump twin risk is secondary to the AA size but remains clinically usable. These factors may aid in the development of methods for pump twin prognosis and the promotion of selective clinical interventions.Birth Defects Research (Part A), 2016.© 2016 Wiley Periodicals, Inc. Birth Defects Research (Part A) 106:1008-1015, 2016. © 2016 Wiley Periodicals, Inc.

A case of twin reversed arterial perfusion (TRAP) sequence in a monochorionic diamniotic triplet pregnancy with two acardiac fetuses

Background: Twin reversed arterial perfusion (TRAP) sequence is a rare anomaly of monochorionic twins involving artery-to-artery anastomoses resulting in a structurally normal “pump” twin that provides circulation to an acardiac twin in a retrograde fashion. Case: Herein we report a rare case of a triplet gestation (TrGA) consisting of two conjoined acardiac TRAP recipients and one surviving normal pump fetus. The TRAP recipients were discordant for their anomalies. We know of only three similar case reports from the literature. Conclusion: Characteristic ultrasound findings allow for the prenatal diagnosis of TRAP sequence and may allow prompt and appropriate treatment to improve the outcome of the pump twin.

Acardiac twin pregnancy: successful intrauterine ablative treatment with alcohol at 14 weeks of gestation

Twin reversed arterial perfusion (TRAP) sequence is a serious condition of monochorionic twin pregnancy, occurring in approximately one in 35,000 cases. First trimester treatment of TRAP sequence is controversial with higher incidence of procedure related complications. Present case demonstrates a TRAP sequence that was managed by intrauterine treatment with one ml 100% pure alcohol injection into the abdominal part of the umbilical artery and obliteration of the acardiac twin at 14 weeks of gestation. Antenatal follow-up was uneventful and elective cesarean section was performed at 39 weeks’ gestation. Postnatal outcome of the pump twin was excellentat 30 months after birth. Early second trimester elective ablation by alcohol injection can be an inexpensive, alternative, and reasonable minimal invasive treatment option to prevent fetal loss of pump twin before mid and late second trimester in perinatology centers where intrafetal cord occlusive methods are not available.

Cardiac failure of the twin reversed arterial perfusion sequence pump twin during the first-trimester: a case report

This article reports a case of prenatal ultrasonographic diagnosis and monitoring of the twin reversed arterial perfusion (TRAP) sequence pump twin and describes progression of the disorder to a severe heart failure and fetal death. Genetic analyses were also performed for both fetuses by array-based comparative genomic hybridization (aCGH).

Forty cases of twin reversed arterial perfusion sequence treated with radio frequency ablation using the multistep coagulation method: a single-center experience.

To report the pregnancy outcomes of patients with twin reversed arterial perfusion (TRAP) sequence treated by radiofrequency ablation (RFA). This was a retrospective study of TRAP sequences treated in a single center between March 2002 and February 2015. Forty patients underwent RFA with expandable tines through a multistep coagulation method between 15 and 26 gestational weeks. The primary outcome was neonatal survival to discharge. The overall survival of the pump twin was 85%. The survival rates in monochorionic-monoamniotic (MCMA) pregnancies and monochorionic-diamniotic pregnancies were 66.7% (4/6) and 87.9% (29/33), respectively. One triplet was treated successfully and delivered at 36 weeks of gestation. One of 35 live births (2.9%) had preterm premature rupture of membranes less than 34 weeks, resulting in infant death. In five intrauterine pump twin deaths, two cases were MCMA twins with cord entanglement, and three cases were MCDA twins with acardius anceps. Our study supports the effectiveness of RFA for TRAP sequence after 15 weeks of gestation. The presence of MCMA twins or acardius anceps is associated with a high risk of pump twin death after RFA. © 2016 John Wiley & Sons, Ltd.

Acardius-myelacephalus: management of a misdiagnosed case of twin reversed arterial perfusion sequence with tense polyhydramnios

Abstract Background: Twin reversed arterial perfusion (TRAP) sequence is the most severe form of twin to twin transfusion syndrome. Survival of the pump twin is threatened by extreme prematurity from polyhydramnios and cardiac failure, necessitating interventions. Rarely, interventions are indicated as a result of maternal life-threatening complications. The management of an acardiac-myelacephalus variant of TRAP sequence, complicated by severe maternal respiratory distress from tense polyhydramnios is presented in this report. Case presentation: A 29-year-old G3P2, Alive2 was referred to the Perinatal Unit on account of ultrasound diagnosed twin gestation with demise of one twin at an estimated gestational age (EGA) of 29 weeks. She was in severe respiratory distress with central cyanosis, and grossly distended abdomen. Ultrasonography revealed twin gestation with cardiac activity in only one twin and polyhydramnios. The second twin had no recognizable human body structure and retrograde umbilical arterial flow. TRAP sequence with tense polyhydramnios was diagnosed. The respiratory distress was relieved with serial reductive amniocentesis, and she was managed conservatively until an EGA of 34 weeks, when she delivered a live twin that weighed 2.05 kg, and an amorphous twin with a rudimentary limb that weighed 1.82 kg following spontaneous rupture of membranes. Monochorionic placentation was confirmed at delivery. The pump twin was discharged in a satisfactory state after a period of observation. Conclusion: TRAP sequence may be easily misdiagnosed due to its rarity, with adverse consequences. Accurate diagnosis of the condition, and the provision of basic facilities for in utero interventions when indicated are necessary for fetal salvage.

Hypothesis acardiac twin pregnancies: Pathophysiology‐based hypotheses suggest risk prediction by pump/acardiac umbilical venous diameter ratios

A total of 75% of monozygotic twins share 1 monochorionic placenta where placental anastomoses cause several serious complications, for example, acardiac twinning. Acardiac twins lack cardiac function but grow by perfusion of arterial blood from the pump twin. This rare pregnancy has 50% natural pump twin mortality but accurate risk prediction is currently impossible. Recent guidelines suggest prophylactic surgery before 18 weeks, suggesting 50% unnecessary interventions. We hypothesize that (1) adverse pump twin outcome relates to easy-to-measure pump/acardiac umbilical venous diameter (UVD) ratios, representing acardiac perfusion by the pump's excess cardiac output. This hypothesis suggests that (2) UVD-ratios are large, mildly varying in cases without complications but small and decreasing when complications develop, thus predicting that (3) UVD-ratios may allow risk prediction of pump twins. In this exploratory clinical pilot, we tested whether UVD-ratio measurements support these predictions. We included 7 uncomplicated (expectant management), 3 elective surgical, and 17 complicated cases (pump decompensation, emergency intervention/delivery or demise). Nine UVD-ratios were measured sonographycally and 18 by pathology. Uncomplicated cases have larger, two serial measurements showing mildly varying UVD-ratios; elective surgical cases show larger UVD-ratios; complicated cases have smaller, two serial measurements showing decreasing UVD-ratios. There were no false-positives, no false-negatives and noncrossing linear trendlines of uncomplicated and complicated cohorts. Our data provide first evidence that UVD-ratios allow risk prediction of pump twins. More early uncomplicated and late complicated cases are needed, for example, in a prospective trial, before the separation between uncomplicated and complicated cohorts is accurate enough to support a well-founded decision on (early) intervention.

Twin reversed arterial perfusion sequence is more common than generally accepted.

Approximately 75% of monozygotic twin pregnancies share one monochorionic placenta where placental anastomoses are virtually always present to connect the two fetoplacental circulations. These anastomoses cause several serious complications such as acardiac twinning. Acardiac twins lack a functional heart but nevertheless show fetal growth because the normal pump twin perfuses the acardiac body through arterioarterial (AA) and venovenous (VV) anastomoses. The widely accepted 1% monochorionic acardiac incidence dates back to 1944 and the associated 1:35,000 pregnancies to 1953. Our aim was to update this analysis. We accepted the 1% (actually 1.1%) monochorionic acardiac incidence due to lack of more precise data, included the recently observed 58% early cessation of acardiac development as well as consequences of assisted reproductive technology, and assessed the incidence of acardiac twinning under conditions of AA-VV anastomoses. Early acardiac monochorionic twinning increased from 1.1% to 1.1/(1-0.58) = 2.6%, from 1:35,000 to 1:9,500 to 11,000 pregnancies, depending on number and method of assisted reproductive technology, and occurs in approximately 1:8 AA-VV anastomoses-containing monochorionic placentas. Early acardiac twinning is not a rare event. The 1944-based 1% acardiac monochorionic incidence has a weak basis and could therefore be (much) larger. Knowing this incidence more precisely may contribute to our knowledge of embryonic splitting in unequal cell masses.

Acardius acephalus amorphus: a propósito de un caso

Los gemelos humanos amorfos, los Chorangiopagus parasiticus o los gemelos con perfusión arterial inversa, son una entidad anormal muy rara, presentada en las gestaciones múltiples monocigotas. Se ha propuesto que la presencia de anastomosis arteria-arteria y vena-vena en una placenta homocigota, la sangre es perfundida por el gemelo hemodinámicamente aventajado (gemelo "bomba") al otro gemelo (gemelo "receptor"). Una inadecuada perfusión, con sangre deprivada de oxígeno, del gemelo receptor es la responsable del desarrollo de las características e invariablemente letales serie de anomalías, incluyendo la acardia y la anencefalia. Típicamente el gemelo "bomba" es estructuralmente normal, pero tienen un riesgo de presentar insuficiencia cardíaca congestiva in útero y sin un tratamiento fallece entre 50 y 75 por ciento de los casos, particularmente si el gemelo receptor pesa más de la mitad del peso del gemelo bomba. A muchos de estos gemelos anormales se les ha encontrado aneuploidía, al igual, pero en menor frecuencia, que en el feto estructuralmente normal. Se presenta el caso de una mujer de 30 años con detección posnatal de un feto acardius amorphus acephalus.

Twin-reversed arterial perfusion sequence associated with decreased fetal cerebral vascular impedance.

Twin-reversed arterial perfusion (TRAP) sequence affects 1% of monochorionic twin pregnancies and is caused by abnormal vascular connections between a pump twin and an acardiac mass. The effects of abnormal vascular connections on cerebral vasculature in the pump twin are unknown. We hypothesize that abnormal cerebral vascular impedance, as assessed by the pulsatility index (PI), is present in pump twins and that fetal intervention alters cerebral impedance. Fetal echocardiograms performed between 2010 and 2013 in pregnancies diagnosed with TRAP (n = 19), recorded at presentation, and uncomplicated monochorionic twin pregnancies (controls, n = 18; 36 fetuses) were analyzed. In all subjects, the middle cerebral artery (MCA)-PI, combined cardiac output (CCO) and cardiothoracic ratio were calculated, and the values for cases and controls were compared. The mean gestational age at the time of echocardiography was 20 weeks in both groups. MCA-PI was lower in TRAP cases than in controls (1.55 (95% CI, 1.47-1.64) vs 1.74 (95% CI, 1.65-1.82), respectively; P = 0.004). CCO in TRAP cases was mildly elevated for gestational age (199.7 (95% CI, 138.4-261.1) mL/min) compared with that of controls (131.4 (95% CI, 102.2-160.7) mL/min). In six TRAP cases with a second echocardiogram available, the mean MCA-PI increased after intervention, from 1.5 (95% CI, 1.3-1.7) to 1.8 (95% CI, 1.4-2.2). TRAP pump twins have lower cerebral vascular impedance than do controls, suggestive of a brain-sparing effect. MCA-PI appeared to increase in a small group of pump twins after intervention. These findings suggest a fetal cerebral autoregulatory response to a high cardiac output state that begins to change after fetal intervention. The long-term implications for neurodevelopmental outcome warrant further study.

Twin reversed arterial perfusion (TRAP) sequence – a case report and review of literature

Twin reversed arterial perfusion (TRAP) sequence (acardiac twin) is a rare complication of monochorionic pregnancy characterized by single arterial to arterial vascular anastomosis between twins. In this unique haemodynamic arrangement, the structurally normal pump twin will perfuse its abnormal co-twin (acardiac) in a retrograde manner through these anastomoses, with potential for cardiac overload and heart failure in the pump twin and high fetal mortality. Definitive fetal intervention has been recommended in the literature for high (>50%) twin weight ratio (TWR). We present a case of twin reversed arterial perfusion managed expectantly as no signs of cardiac decompensation were encountered in the pump twin.

Twin Reversed Arterial Perfusion (TRAP) Sequence: A Case Report in Fallujah Maternity and Children Hospital, Fallujah, Iraq

Introduction. Twin reversed arterial perfusion (TRAP) sequence is a rare complication of multiple pregnancy caused by defects in early embryogenesis. The pump twin supplies the acardiac recipient twin with blood, and although the pump twin is usually structurally normal, congenital anomalies have sometimes been reported. We report a case of twin reversed arterial perfusion sequence with feet polydactly in the surviving pump twin. This was the 1st case reported in Fallujah city, Iraq. Case report. A 22 years old. gravida 2, para 0. abortion 1, full term lady presented to the delivery room with labour pain with no history of any prenatal care. She gave no history of any familial congenital anomaly and there was no history of consanguinity with her hasbund. She has been referred for cesearian section delivery as an emergency as there was no progress in labour. Ultrasound examination at the delivery room revealed the diagnosis of monozygotic twin, one was normal & the 2nd was diagnosed as (abnormal) with difficulty in visualization of the fetal parts and gender. Conclusion. Twin-Reversed Arterial Perfusion (TRAP) sequence is a rare complication of monozygotic multiple gestation. Accurate antenatal diagnosis is essential to improve the prognosis of this rare entity.

Acardiac Twin: A rare Complication of Monochorionic Monoamniotic Twin

Acardiac malformation, also known as twin reversed arterial perfusion (TRAP) sequence, is a unique complication of monochorionic twinning., occurring with a reported incidence of 1 in 35 000 deliveries. It is characterized by lack of heart development associated with a spectrum of malformations and anomalies in one of the twins, which is perfused in a paradoxical retrograde fashion by a structurally normal ‘pump’ twin through a single artery-to-artery anastomosis. There is usually a normally formed donor twin who has features of heart failure as well as a recipient twin who lacks a heart (acardius) and various other structures.It is caused in the embryo by a large artery-to-artery placental shunt, often also accompanied by a vein-to-vein shunt. The common complications include congestive cardiac failure in the pump twin, polyhydramnios and preterm delivery.