The Basic And Clinical Study Of Twin Reversed Arterial Perfusion Sequence By Prenatal Ultrasonography

Twin reversed arterial perfusion sequence (TRAP) is a serious complication of monochorionic twins. The pump fetus will occur high output cardiac failure and premature birth and demise intrauterine or in the neonatal period if not being untreated. This research about the TRAP sequence focus on prenatal diagnosis, pathogenesis, the mode of vascular anastomoses between the pump fetus and the acardiac fetus, pathology, and prognostic factors of the pump twin. The study will help clinicians and patients to monitor or to treat the TRAP sequence in reasonable gestational age, to choose the best methods to improve the outcome of the pump fetus and to guarantee maternal safe.PART I Prenatal sonographic diagnosis of twin reversed arterial perfusion sequenceObjective:To explore the clinical value of prenatal ultrasound in the diagnosis of twin reverse arterial perfusion sequence (TRAP), and to deepen more understanding of the rare malformation.Methods:We retrospectively analyse64cases of TRAP pregnancies that were diagnosed by prenatal ultrasound and clinic among518,269pregnant women from May2001to May2014in Hubei Women and Children’s Hospital. The prenatal ultrasound imaging and clinical data after fetus termination or delivery were analyzed, and the different types of TRAP are compared to pathology after fetus termination or delivery.Results:The total prevalence of TRAP was1.29/10000in Hubei Women and Children’s Hospital, mainly male fetus. All of the64cases were monochorionic twins, and diamniotic twins were more commom. The rate of survival pump fetus was21.87%. It would be probably diagnosed as singleton before11weeks. There were difference of the diagnostic level in different hospital, and often misdiagnosed the acardiac fetus as stillbirth. There were three types based on vascular perfused in the acardiac fetus. Type Ⅰ44cases had vascular perfused, accounted for68.75%of all subjects. The acardiac fetus with an absent heart that is reversely perfused via an umbilical artery to pump fetus. Type Ⅱ12cases had vascular perfused discontinued in subsequent gestational age, accounted for17.75%. Ultrasound examination found vascular perfused toward the acardiac fetus but disappearing in subsequent examination. Type Ⅲ8cases without vascular perfused, accounted for12.5%. Ultrasound hadn’t detected blood signal in the acardiac fetus.Conclusions:The survival rate was low in pump fetus without treated. Prenatal ultrasound examination was a primary and important method for diagnosis of TRAP, which could diagnose TRAP in early pregnancy, evaluate the cardiac function of the pump fetus, fetal subsidiary structure and prognosis. PART II Basic research of twin reversed arterial perfusion sequenceObjective:To explore the relationship between the cause of twin reversed arterial perfusion sequence and chromosomal abnormalities, to discuss the special placental vascular perfusion pattern of the two fetus via vascular cast and study the pathological foundation of TRAP.Methods:Fourteen fetus of the10TRAP were subjected to chromosome karyotype analysis and genetic testing. Ten cases of TRAP were subjected to placenta vascular cast, in addition,27cases pumps and35cases of acardiacs were subjected to pathologic examination and tissue slice.Results:No chromosome karyotype abnormality was found in14fetus of the10TRAP; Prenatal ultrasonography was highly accurate in demonstrating pump twins, skin edema, lymphatic hydrocele, acardia, spine, lower limbs, acephalous, abdominal organ and omphalocele, but had difficulty in finding cranial dysplasia and externalia and was not able to demonstrate internal genitalia. Fourteen cases of placental vascular cast can be divided into four categories:type Ⅰ included6cases with direct vascular anastomosis pattern of artery-artery and vein-vein; type Ⅱ consisted of5cases with artery-artery and vein-vein, in addition, a few placental vascular branches could be seen in umbilical atery and vein in acardic fetus; type Ⅲ own only1case,one vascular of the acardia was interlinked to the pump twin; type Ⅳ, there was no apparent vascular between acardia and pump twin.Conclusions:The study of prenatal ultrasound examinations and placenta vascular cast provided important information for exploring the special vascular anastomosis pattern and placenta blood circulation as well as the prognosis. Colour Doppler ultrasonogra-phy is the first choice for prenatal diagnosis of TRAP. PART Ⅲ Clinical research about twin reversed arterial perfusion sequenceObjective:To explore the outcome of twin reverse arterial perfusion sequence (TRAP).Methods:All subjects were divided into two groups according to the pump fetus survived or died. A comprehensive analysis of prenatal sonographic image, the twins’ karyotype, pathology and placental vascular cast were taken.Results:Fourteen pump fetus survived,50fetus died. All of the50cases,18cases died intrauterine,6cases is stillbirth in the neonatal period,26cases were termination,10pump fetuses were structural malformation and20pump fetuses have performance of the failure of cardiac function in the50stillbirth cases. In the survived group, there was no fetus with failure of cardiac function,3cases revealed polyhydramnios. A few placental vascular branches could be seen in umbilical atery and vein in acardic fetus.Conclusions:The outcome of the pump fetus was interfered by many factors, such as its own structure, the function of heart and brain, the structure and growth rate of the acardiac fetus, the twins’subsidiary structure, placenta and chorionic type and so on. If it was untreated, the prognosis of the pump fetus was poor.