15例双胎反向动脉灌注序列症的自然病程及围生儿预后探讨

目的:了解双胎反向动脉灌注序列症(TRAP序列症)的自然病程,分析其围生儿预后。方法:回顾性分析我院2008年7月至2011年12月收治的TRAP序列症15例患者的临床资料,对足月产、早产、流产及平均分娩孕周等资料进行统计,分析无心畸胎/供血儿的腹围比(AC比值)、脐动脉搏动指数(UA-PI)比、供血儿心脏情况等,并追踪供血儿出生后1年的健康状况。结果:15例TRAP序列症患者无心无头型11例,无心无脑型4例。10例孕早期超声检查误诊为双胎之一死亡(3例)、胎儿水肿(2例)和颈部淋巴水囊瘤(5例)。供血儿情况:羊水过多2例(1例引产,1例自然流产);心功能不全2例(1例因合并先天性心脏病引产,1例早产);羊水过多合并心功能不全1例(自然流产)。无心畸胎情况:无心畸胎血流自然阻断2例(13.3%),其中1例孕37周突发宫内死胎,1例继续妊娠(情况稳定);无心畸胎血流微弱(UA-PI比值<0.7)8例(53.3%),其中自然流产2例,引产1例,分娩活胎3例(追踪1年,3例新生儿均健康),继续妊娠2例(情况稳定);无心畸胎血流丰富5例(33.3%)(均引产)。另外无心畸胎出现迅速增长(AC比值>50%)共10例(66.7%),其中引产7例,自然流产1例,仅2例剖宫产分娩存活。结论:无心畸胎较小、血流不丰富者,自然病程良好。出现无心畸胎迅速生长、供血儿心力衰竭或水肿,提示胎儿死亡风险高或预后不良。     

Term birth after midtrimester hysterotomy and selective delivery of an acardiac twin.

OBJECTIVE: Our aim was to determine whether hysterotomy and selective removal of an acardiac twin could improve the outcome of the "pump" twin. STUDY DESIGN: A literature and case review of the outcome of the acardiac twin malformation was performed. When an acardiac malformation was diagnosed at 19 weeks' gestation the patient was monitored with weekly ultrasonographic examinations. At 23 weeks' gestation, no blood flow could be demonstrated to the acardiac twin and it was thought that the continued presence of the acardiac twin posed a risk to the "pump" twin. A midtrimester hysterotomy was performed and the acardiac twin was delivered. RESULTS: After the midtrimester hysterotomy, the pregnancy progressed to term and a healthy female infant was delivered by elective cesarean section at 37 weeks' gestation. CONCLUSION: Midtrimester hysterotomy may be a useful intervention in cases of twinning when one fetus is a threat to the health of the other.     

Selective reduction of acardiac twin by radiofrequency ablation

OBJECTIVE: Acardiac/acephalic twinning is a rare anomaly in which a normal "pump" twin perfuses an acardiac twin, which results in twin reversed arterial perfusion sequence. A novel technique for selective reduction and obliteration of blood flow in the acardiac twin is described. STUDY DESIGN: Thirteen consecutive cases of monochorionic twin gestation with twin reversed arterial perfusion sequence underwent selective reduction of the abnormal twin with the use of radiofrequency ablation. Under direct real-time sonographic guidance, a 3-mm (14-gauge) radiofrequency ablation needle was percutaneously inserted through the maternal abdominal wall into the intrauterine fetal abdomen at the level of the cord insertion site of the acardiac twin. Energy was applied until termination of blood flow to the acardiac fetus was documented by Doppler ultrasound scanning. RESULTS: All 13 mothers tolerated the procedure without major complications. All 13 "pump" fetuses have been delivered. Twelve of 13 infants are alive and well. The first patient in this series was delivered at 24.4 weeks and the infant subsequently died from complications of prematurity. Average gestational age at intervention was 20.7 weeks, and the average gestational age at delivery was 36.2 weeks. CONCLUSION: Radiofrequency ablation is a minimally invasive, percutaneous technique that can effectively obliterate blood supply to an acardiac twin to preserve and protect the pump twin.     

Twin reverse arterial perfusion: Timing of intervention

Twin reverse arterial perfusion (TRAP) sequence is a severe anomaly in monochorionic twins where one twin has profound corporeal underdevelopment and acardia. The normal “pump” co-twin provides blood flow to the acardiac twin through placental anastomoses which may lead to cardiac failure and pump twin demise as well as preterm delivery from severe polyhydramnios. Treatments include radiofrequency ablation, bipolar cord coagulation, and intrafetal laser with each aimed at occluding blood flow to the acardiac twin. However, none of these modalities has proven superior in terms of either pump twin survival or minimization of complications, including preterm premature rupture of membranes, preterm birth, or unexpected co-twin demise. The optimal timing of treatment is also unknown, without clear indications for intervention versus expectant management. Very early treatment of TRAP (i.e., <16 weeks) has been proposed to reduce first-trimester demise; however, this approach remains experimental. Further investigation is required to determine the best treatment and timing of intervention for TRAP.     

Monochorionic, diamniotic triplet pregnancy complicated by twin reversed arterial perfusion sequence. Postpartum autopsy of placenta and acardiac fetus

The twin reversed-arterial-perfusion sequence (TRAP) is a severe complication of monochorionic twin pregnancies characterized by the hemodynamic dependence of a "recipient" twin from a "pump" twin. The recipient twin exhibits lethal abnormalities including acardia and acephaly. The pump twin has a mortality rate of 50% as a result of high-output heart failure. We present a case of a 24-year-old female, gravida 2, para 2, with monochorionic diamniotic triplet pregnancy. The sonographic examination at 18 weeks' gestation revealed acardiac-acephalus fetus. Reversed arterial perfusion sequence was confirmed with Doppler sonography. Postpartum autopsy examination of placenta and acardiac fetus (acardius anceps) was detailed described.     

Feto acardio en gestación gemelar a término

Twin reversed arterial perfusion sequence (TRAP) is a serious complication of monochorionic twin pregnancies, in which one twin perfuses the other twin (an acardiac fetus) via large arterio-arterial and veno-venous anastomoses.We report a case of monochorionic twin pregnancy at term, in which the second twin was an acardiac fetus with only an undeveloped lower limb and rudimentary colonic tissue. The first twin was born healthy, a very rare outcome in this entity as the pump twin usually shows distinct degrees of cardiac overload, leading to intrauterine death from heart failure in more than 50% of cases.     

The case of an acardiac headless twin, review of the literature

INTRODUCTION: Monochorial twin pregnancies are characterized by the presence of vascular connections between the twins. These connections can be at the origin of pathologies such as the transfused/transfuser syndrome or the TRAP syndrome which is defined as the association of a headless, acardiac twin with a healthy twin, which is the subject we will study and then review the literature. THE CLINICAL CASE: The case of an acardiac, headless twin which was not diagnosed during pregnancy and was discovered at birth. DISCUSSION AND CONCLUSION: The TRAP syndrome is a very rare phenomenon. Yet, it is crucial to diagnose it as early as possible during pregnancy so as to offer adequate supervision. It is associated to a high death rate in the healthy twin caused by anemia and heart failure. There are therapeutic means to stop vascular anostomoses between the twins so as to perform a selective feticide.     

Prenatal diagnosis of fetal heart failure in twin reversed arterial perfusion syndrome

Diagnosis of twin reversed arterial perfusion (TRAP) syndrome is a rare fetal anomaly that can be misdiagnosed on prenatal ultrasound. We confirmed the use of colour-flow Doppler for prenatal diagnosis of TRAP syndrome and used serial fetal echocardiography for non-invasive evaluation of the fetus. A patient with twin intrauterine pregnancy was referred to our centre with suspected intrauterine fetal demise following a 16 week ultrasound. Serial colour-flow Doppler ultrasonography demonstrated retrograde arterial flow in an acardiac twin. Following diagnosis of TRAP syndrome, serial fetal echocardiography was employed to follow the normal twin for signs of heart failure, including right atrial dilation, tricuspid regurgitation and pericardial effusion. When early signs of fetal heart failure were suspected a viable female infant was delivered at 32 weeks' gestation. We suggest that serial fetal echocardiography represents a non-invasive approach that can be used to follow fetal cardiac function of the normal twin in TRAP syndrome.     

The normal fetus of an acardiac twin pregnancy: perinatal management based on echocardiographic and sonographic evaluation

Experience with three prenatally diagnosed pregnancies complicated by an acardiac twin reveals that ultrasonography and echocardiography are helpful in detecting early signs of in-utero congestive heart failure in the normal twin. The use of Doppler blood flow analysis to determine direction of blood flow, post-mortem placental and fetal angiography, and umbilical cord blood gas determination provided proof that retrograde arterial perfusion occurs in the acardiac fetus. In a fourth pregnancy, an experimental approach to occlude the acardiac twin's umbilical cord was attempted, but was unsuccessful.     

Twin-Reversed Arterial Perfusion (TRAP) Sequence: Case Reports and Review of Literature

Summary: The twin reversed-arterial-perfusion (TRAP) sequence found in monozygotic twins is a consequence of primary or secondary cardiac development disruption and direct arterioarterial and venovenous placental anastomoses. Associated findings include the presence of a single umbilical artery (66%) and chromosomal abnormalities in the acardiac twin (33%). Morphological abnormalities in the acardiac twin are consistent with perfusion of tissues supplied by the common iliac and lower branches of the aorta with deoxygenated blood. The pump or donor twin may develop cardiac failure because of the anomalous perfusion circuit. Polyhydramnios is significantly associated with the presence of renal tissue in the acardiac twin. An acardiac pump twin weight ratio (>50%) is associated with the development of polyhydramnios and preterm labour. Identified high-risk factors for poor obstetrical outcome include: acardiac anceps, polyhydramnios, acardiac twin with ears, and pump twin cardiac failure. Management options include elective termination, observation (serial cardiotocography (CTG), ultrasonography and echocardiography) and selective nonsurgical interventions (indomethacin, digitalis, tocolysis). Additionally, surgical interventions (hysterotomy with selective delivery of the acardiac twin or ligation of the acardiac twin's umbilical cord), and ultrasound-guided embolization of the acardiac twin's umbilical artery with absolute alcohol, platinum coils, or thrombogenic coils have been reported. The most appropriate interventions for the varous clinical presentations of this disorder are as yet undetermined, and conservative nonintervention is often appropriate. Long-term follow-up data on surviving pump twins are lacking. It is anticipated that centres with active study protocols for these conditions will best serve patient care and clinical research needs.     

The management of acardiac twins: a conservative approach

OBJECTIVE: Optimal management of acardiac twin pregnancies is controversial. Data suggest a 50% mortality rate in the "pump" twin when the pregnancy is managed expectantly. Because of increased antenatal diagnosis, outcomes in expectantly managed cases may be better than reported. Our objective was to determine the outcome of expectantly managed acardiac twin pregnancies. STUDY DESIGN: All cases of antenatally diagnosed acardiac twins delivered in our community between 1994 and 2001 were ascertained. All were managed expectantly. Perinatal outcome of pump twins was the primary outcome variable. RESULTS: Ten cases were identified. Nine women were delivered of healthy pump twins. There was one neonatal death. The mean gestational age at delivery was 34.2 weeks. The mean weights of the pump and acardiac twins were 2279 g and 1372 g, respectively. CONCLUSION: Neonatal mortality of pump twins in antenatally diagnosed acardiac twin pregnancies may be considerably less than reported. Expectant management with close antepartum surveillance deserves consideration.     

Treatment of twin reversed arterial perfusion sequence by septostomy and amniodrainage: a case report

Introduction An acardiac fetus is the most severe malformation seen in humans. It is an extremely rare complication, occurring in approximately 1% of all monozygotic twin gestations, with an incidence of about 1 in 35,000 births. This malformation happens as a result of the syndrome of reversed arterial perfusion of the acardiac twin from the other normal fetus (pump twin), due to the presence of arterio-arterial anastomoses in a monochorionic placenta. Several obstetric and perinatal complications have been associated to this anomaly and several treatments have been proposed to reduce the morbimortality of the pump twin. There’s no report in MEDLINE about the treatment of twin gestations with acardiac fetus through septostomy. Case report The present article reports a case of reversed arterial perfusion sequence complicated by polyhydramnios diagnosed at 19th week of pregnancy, treated with septostomy and serial amniodrainage. Discussion This case presented it demonstrate favorable development of the gestation, with labor happening at 35 weeks gestation and pump twin presenting good vitality conditions. In cases with no major factors of bad prognosis, septostomy combined with amniodrainage could be an interesting therapeutic option for a safe and efficacious management of selected cases of TRAP sequence.     

Successful intrauterine treatment with alcohol ablation in a case of acardiac twin pregnancy.

Acardiac twinning is a rare obstetric condition unique to monochorionic twin gestation and the pump twin has high perinatal mortality. We report an acardiac twin pregnancy, in which the pump twin presented with intrauterine growth restriction and oligohydramnios, and grossly hydropic acardiac fetus measured 12 x 14 x 18 cm, and with no cardiac activity at 27 weeks of gestation. We treated the acardiac fetus with 1 ml alcohol ablation in utero, and delivered a live male baby weighing 1750 g at 36 weeks' gestation.     

Twin reversed arterial perfusion sequence: two different heartbeats in one umbilical cord - rare finding in monochorionic twin pregnancy

The development of twin-twin transfusion syndrome complicates 5-35% of twin pregnancies with monochorionic placentation. Acardiac twinning is the most extreme manifestation of pathological vascular anastomoses between twins. An acardiac twin is a rare complication of multifetal pregnancy, reported in the literature with an incidence of 1% in monochorionic twin pregnancies, i.e. 1/35 000 pregnancies, and more than 400 cases have been described. We review the literature on this subject and report a special case of twin reversed arterial perfusion (TRAP) sequence in a twin pregnancy with the rare finding of a functional univentricular circulation pump in the acranius, its antenatal ultrasound diagnosis and postnatal findings. Remarkably, prenatally we could demonstrate two different arterial pulsations in the umbilical cord of the acranius. Etiological hypotheses of the TRAP sequence and new implications for risk-adapted therapeutic options are discussed.     

Utility of Doppler velocimetry in predicting outcome in twin reversed-arterial perfusion sequence

OBJECTIVE: The aim of this study was to describe Doppler velocimetric findings in pregnancies complicated by the twin reversed-arterial perfusion sequence and to determine the association of these findings with pregnancy outcome. STUDY DESIGN: Six twin pregnancies complicated by twin reversed-arterial perfusion sequence had ultrasonographic and Doppler studies performed between 1990 and 1997. Pulsatile vessels in the umbilical cords of the pump and acardiac twins were insonated, and reversal of flow was confirmed in all cases. Resistive index values were calculated, and the difference in resistive index between the pump and acardiac twin in each pair was evaluated as a marker of pregnancy outcome. RESULTS: Five of 6 pump twins survived the immediate neonatal period. Although 5 of the acardiac twins had abnormally elevated Doppler index values, no ratio of systolic to diastolic velocity or resistive index value of the acardiac twin alone was associated with either a good or poor prognosis for the pump twin. Among the 3 pump twins with good outcomes, all had a resistive index difference >0.20. Among the 3 pump twins with poor outcomes, all had small resistive index differences (<0.05). CONCLUSION: We found larger differences in resistive index to be associated with improved outcome of the pump twin in pregnancies complicated by twin reversed-arterial perfusion sequence. Smaller resistive index differences were associated with poor outcome, including cardiac failure and central nervous system hypoperfusion.     

产前超声诊断多胎妊娠无头无心反向动脉灌注三例

目的 探讨双胎无心反向动脉灌注（twin reversed arterial perfusion TRAP）的产前超声声像图特征。方法 回顾性分析3例产前超声诊断为TRAP的超声图像与随访结果，总结声像图特点。结果 2例产后病检证实为TRAP，1例失访。TRAP的特点是，双胎或三胎中均有一个胎儿无头无心畸形，胸腹腔内没有正常内脏结构，无正常上肢结构，可见下肢及下肢运动。皮肤及皮下组织明显增厚，均为单脐动脉；彩色多普勒显示无心胎儿体内出现没有心脏的血液循环通路；频谱多普勒记录到进人胎儿体内脐血管为动脉频谱，出胎儿腹壁的脐血管为静脉频谱，形成了与正常胎儿灌注方向完全相反的灌注特点。结论 多胎妊娠中（包括双胎和三胎）若有单卵双胎，且其中之一伴有严重畸形、无心脏结构与搏动，彩色多普勒记录到进入无心胎儿体内的脐血管为动脉频谱，出胎儿的血管为静脉频谱，为TRAP的重要声像图特征。     

Intrauterine treatment for an acardiac twin with alcohol injection into the umbilical artery

An acardiac twin is a unique complication of monochorionic twinning, in which a normal pump twin perfuses the acardiac twin. The mortality rate of the pump twin is greater than 50%. Herein we present the successful treatment of an acardiac twin with alcoholization as follows. An acardiac twin was diagnosed at 24 weeks gestation. Circulation interruption of the acardiac twin was successfully achieved by injection of absolute alcohol (5 mL) into the intra-abdominal umbilical artery. Serial ultrasound after the procedure revealed normal growth of the pump twin, whereas the acardiac twin was shrinking. Spontaneous premature delivery at 34 weeks gestation resulted in a normal surviving female baby weighing 2410g and an acardiac female fetus weighing 300g. This experience suggests that this simple technique may be an alternative treatment for an acardiac twin.     

Fetal therapy in utero by blockage of the umbilical blood flow of acardiac monster in twin pregnancy

We studied a life-saving method for the unaffected twin in two recent patients who had acardiac monster in twin pregnancy. We succeeded in blocking the umbilical blood flow of the acardiac monster in utero as radical treatment for this abnormality in one of the patients. In case 1, tocolysis and amniocentesis with puncture to the cyst of the acardiac monster were performed to prevent premature labor. However, the patient underwent premature labor at 27 weeks of gestation, and the newborn died. In case 2, fetal treatment was given: A steel coil was placed in the umbilical cord close to the abdominal wall of the acardiac monster under ultrasonographic guidance at 23 weeks of gestation to block blood flow. As a result, no enlargement of the acardiac monster was observed, and the cardiac function of the unaffected fetus improved. At 38 weeks of gestation, the patient delivered a normal baby weighing 2,237g and an acardiac monster weighing 110g. There were no complications in either the mother or newborn. There has been no report describing blockage of the umbilical blood flow of an acardiac monster in utero. Our method is considered efficient and less risky to the mother and the unaffected twin.     

Secuencia TRAP. Diagnóstico diferencial con gemelo muerto

TRAP sequence occurs in 1% of monochorionic twin pregnancies. We present an atypical case of TRAP sequence in which the acardiac twin was properly formed and the cranial and cardiac structures could be identified. The differential diagnosis between TRAP phenomenon and intrauterine death of one twin was performed on the basis of other suspicious ultrasound signs, such as the presence of a single umbilical artery, a dorsal hygroma, and a short cord. The definitive diagnosis was established by Doppler, which showed an arterio-arterial anastomosis and reverse flow in the dead twin.     

Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning

Acardiac twinning affects 1 in 100 monozygotic twin pregnancies and 1 in 35,000 pregnancies overall. The presence of an acadiac twin requires the normal (or "pump") twin to provide circulation for itself, as well as the acardiac sibling. In many cases the acardiac twin is almost equal to the normal twin. The principal perinatal problems associated with acardiac twinning are pump-twin congestive heart failure, maternal hydramnios, and preterm delivery. We reviewed the perinatal courses of 49 acardiac twin pregnancies to identify factors prognostic of favorable outcome. The overall perinatal mortality was 55%, primarily associated with prematurity. Mean (+/- SD) gestational age at delivery was 29 +/- 7.3 weeks, with a mean (+/- SD) normal twin weight of 1378 +/- 1047 gm. The acardiac weight averaged 651 +/- 571 gm. However, the occurrence of hydramnios, the occurrence of preterm labor, and perinatal outcome were strongly related to the ratio of the acardiac and pump-twin's weight. The mean overall ratio of the twin weights was 52% +/- 42%. However, the mean weight ratio for patients delivered before 34 weeks was 60% versus 29% (p less than 0.04). Preterm delivery was strongly associated with the development of hydramnios and congestive heart failure in the pump twin (p less than 0.01). If the twin-weight ratio was above 70% (25% of cases), the incidence of preterm delivery was 90%; hydramnios, 40%; and pump-twin congestive heart failure, 30% compared with 75%, 30%, and 10%, respectively, when the ratio was less (p less than 0.05). Regression of the weight of the acardiac twin against its longest dimension (L) resulted in this equation for prediction of acardiac weight: Weight (grams) = 1.2 L2-1.7L; r = 0.79, p less than 0.01. These data suggest that estimation of the relative weights in acardiac twins provides prognostic information regarding outcome. Poor outcome occurs with congestive heart failure and hydramnios in the normal twin. Use of the above data may assist in counseling patients and determining optimal management.