Arterial Perfusion Sequence Research Articles

Sonographic detection of fetal abnormalities before 11 weeks of gestation.

Sonographic detection of fetal abnormalities before 11 weeks of gestation.

TRAP) Secuencia de perfusión arterial reversa en embarazo gemelar monocoriónico con feto acárdico. Caso Clínico.

Objetive: Develop a review of the pathophysiology, diagnosis, treatment and management of reversed arterial perfusion.The reversed arterial perfusion sequence, known in English literature as TRAP sequence (twin reversed arterial perfusion (1), pathology associated with complications of monochorionic twin pregnancy, (2) is the absence of a well-defined cardiac structure on a twin (the acardiac twin), which is kept alive by his co-twin (the pump twin) through an arterial-arterial surface placental anastomosis. (3) the normal twin accompanying the acardiac has a mortality of 60% ; morbidity is mainly associated with congestive heart failure (4) while the acardiac twin has a mortality of 100% Apropos of a case reversed arterial perfusion syndrome TRAP diagnosed in the second trimester of pregnancy will be displayed and evaluate it. Management made in the service of Gynecology, service image and Pathology service and the associated perinatal outcomes. Keywords: acardic Fetus, perfusion sequence reversed arterial, sequence TRAP, monochorionic pregnancy twin

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

Twin 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. We 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. The 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). Most of acardiac twins were acardia with simple IVP. Morphology and IVP of acardiac twins were not associated with UA Doppler indices.

Intrafetal laser for midtrimester TRAP sequence-experience from a single center.

To report our experience and evaluate outcomes in monochorionic pregnancies with Twin Reversed Arterial Perfusion sequence with intrafetal laser therapy. Retrospective review of records of all pregnancies with TRAP sequence treated by intrafetal laser therapy between 2011 January and 2015 December that were retrieved and analysed. Electronic search of the scan database retrieved 57 cases of TRAP sequence during the study period, 7 triplets and 50 monochorionic twins. Intrafetal laser was done in 27 cases, 22 cases of twins and 5 cases of triplets. In the twins group, median gestational age at intervention was 22.5 weeks, the earliest done at 16.3 weeks. The median gestational age at delivery and birth weight was 37 weeks and 2.5 Kgs. The median procedure and delivery interval was 14 weeks. Live birth rate was 17/22 (77%) the pump survival rate was 16/22 (73%). Pregnancies with non-surviving pump were 5 in numbers (5/22). A repeat procedure was warranted in one case. In the triplet group, median gestational age at intervention, delivery and procedure delivery interval was 18, 35 and 17 weeks. Intrafetal laser is simple, effective and the treatment of choice to interrupt the vascular supply to acardiac twin.

Fetal therapies as standard prenatal care in Japan.

With recent advances in fetal medicine, various attempts have been made to save fetuses facing perinatal death or devastating consequences despite optimal management after birth. The concept of the fetus as a patient has been established through the application of in utero treatments. This paper reviews fetal therapies in order to highlight the role of perinatal medicine as standard prenatal care. Fetal therapies consist of medical therapy, percutaneous ultrasound-guided surgery, fetoscopic surgery, and open fetal surgery. In the 1980s, with advances in ultrasound imaging, percutaneous ultrasound-guided surgeries such as vesicoamniotic shunting for lower urinary tract obstruction and thoracoamniotic shunting (TAS) for fetal hydrothorax (FHT) were started. In the 1990s, fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) was introduced, and later, a fetoscopic approach for congenital diaphragmatic hernia was also established. The revival of open fetal surgery, introduced in the 1980s by pediatric surgeons, began in the 2010s after a successful clinical study for myelomeningocele. Although many fetal therapies are still considered experimental, some have proven effective, such as FLS for TTTS, TAS for primary FHT, and radiofrequency ablation (RFA) for twin reversed arterial perfusion (TRAP) sequence. These three fetal therapies have been approved for coverage by Japan National Health Insurance as a result of clinical studies performed in Japan. FLS for TTTS, TAS for primary FHT, and RFA for TRAP sequence have become standard prenatal care approaches in Japan. These three minimally invasive fetal therapies will help improve the perinatal outcomes of fetuses with these disorders.

Twin Reversed Arterial Perfusion (TRAP) Sequence: A Rare Case Report of an “Acardiac” Twin

A 32 year-old-pregnant female, presented to the labour and delivery department with contractions and leaking fluid. A vaginal mass was noted on digital examination. Obstetrical ultrasound demonstrated a twin pregnancy with a normal male fetus and a dysmorphic fetus with cardiac activity. Cesarean section was performed due to premature rupture of membranes (PROM) and ultrasound findings. A normal live male infant was delivered, required minimal neonatal care, and is healthy to date. A non-viable anomalous twin and the shared placenta was sent for autopsy. Pathology diagnosis was twin reversed arterial perfusion (TRAP) sequence and hemiacardius twin. TRAP sequence was a prenatal differential diagnosis but seemed unlikely with uncharacteristic findings and rare incidence. This case report emphasizes the importance of early and accurate ultrasound detection of multiple pregnancies, fetal autopsy, and the complexity of TRAP sequence.

Acardiac Twin: The Overlooked Diagnosis. A Recent Case Report and Review of Literature

Acardiac twin or Twin Reversed Arterial Perfusion sequence (TRAPS) is a unique and extreme complication seen in monochorionicmultifetal pregnancies. It comprises an often normal twin pumping deoxygenated arterial blood in retrograde through an acardiac, dysmorphic counterpart. Recently, a 2.6% incidence among monochorionic twins has been cited. For the pump/donor twin, mortality often exceeds 50% commonly from heart failure and prematurity. Acardiac twinning with a surviving donor twin has yet to be described in our setting. We describe a 28-year-old para 0+1 presenting in the second trimester with a twin pregnancy complicated by polyhydramnios of the donor viable twin and a non-viable recipient twin inadvertently diagnosed as a single fetal demise of a grossly malformed twin. The case was expectantly managed resulting in spontaneous preterm delivery and survival of the donor twin. TRAPS necessitates a high index of suspicion and a thorough sonographic evaluation in monochorionicmultifetal pregnancies.

Selective fetal termination in monochorionic twin pregnancies - pregnancy outcome after bipolar cord coagulation and interstitial laser coagulation

Introduction/Objective. In this paper we present the perinatal outcome after selective fetal termination (SFT) in monochorionic (MH) twins done by bipolar cord coagulation (BCC) and interstitial laser coagulation (ILC). Methods. During a five-year period, SFT was done in 22 MH twins. BCC was done in 15 and ILC in seven cases. We registered the indication for SFT, gestational age at SFT, immediate postoperative death and late death of the co-twin, PPROM (preterm pre-labor rupture of membranes), gestational age at delivery/abortion, procedure-to-delivery interval, mode of delivery, neonatal body weight and 5-minute Apgar score. Results. Live birth was significantly higher after BCC than after ILC (86.7:57.1%). Gestational age at intervention was higher in BCC (20.2 ? 1.8 : 16.5 ? 1.7 weeks). Gestational age at delivery/abortion was lower for ILC (32.5 ? 4.8 : 27.5 ? 9.5 weeks); however, there was no difference when comparing live births only (33.8 ? 3.7 : 34.7 ? 4.5 weeks). There was no difference between procedure-to-delivery/abortion interval (86.7 ? 33.7 : 77.1 ? 73 days); however, the interval was significantly higher after ILC when comparing live births only (93.3 ? 33 : 133 ? 30.9 days). There was no difference in PPROM (26.7:14.3%); preterm delivery (69.2:50%); Cesarean section rate (84.6:75%); neonatal body weight (2174 ? 82.4 : 2475 ? 823 g); or Apgar score (7.7 ? 1.9 : 9.2 ? 1). Conclusion. There is no ideal method of SFT in MH twins. Success of each SFT method depends upon the correctly set indication, gestational age at the procedure, and the SFT technique. The risk of co-twin death is lower after BCC than after ILC. As in Narodni Front University Clinic for Gynecology and Obstetrics better results were achieved after BCC, this method became a standard for SFT in MH twins, except in cases of twin reversed arterial perfusion sequence before 16 weeks.

233: Prenatal ultrasound morphology and angioarchitecture of acardiac twin

Twin-reversed arterial perfusion (TRAP) sequence is characterized by paradoxical perfusion of the acardiac (A) by the pump twin (P). Ultrasound morphology (acardia vs hermicardia) and arteriovenous shunting (AVS) (single vs multiple) of A may be prognosticative for perinatal outcomes. Prospective Observational Study – Primary. Twenty-one TRAP sequence cases were evaluated. Weight ratio between A and P (A/P Wt), differences of systolic/diastolic ratio (UA ΔS/D), resistance index (UA ΔRI), and pulsatility index ratio (UA PI A/P) of the umbilical arteries between A and P were assessed. Radiofrequency ablation (RFA) was performed at 16-24 weeks of gestation. The median (min, max) gestational age at diagnosis (GA Dx) was 18 (11, 27) weeks. Acardia (n=14) and hemicardia (n=7) correlated with single (n=16) and multiple AVS (n=5), respectively. (p< 0.05) The A/P Wt, UA ΔS/D, UA ΔRI, and UA PI A/P in acardia with single AVS (n=13), acardia with multiple AVS (n=1), hemicardia with single AVS (n=3), and hemicardia with multiple AVS (n=4) were not different. (p >0.05) Seven cases were diagnosed at < 16 weeks’ (5/7 were acardia with single AVS (1/5 P died before RFA)). Their morphology and AVS remained unchanged until RFA. There were significant inversed correlations between GA Dx and intervention, and GA at delivery and birth weight. (r=-0.62--0.82, p< 0.05) The UA DSD and UA DRI inversely correlated with UA PI A/P (r=-0.71--0.88, p< 0.05), but not with A/P Wt. (p >0.05) Acardia with single AVS may have poor prognosis. Ultrasound morphology and AVS patterns of A may augment the prognostication for TRAP sequence.

First-trimester intervention in twin reversed arterial perfusion sequence.

To report the outcome of monochorionic twins with twin reversed arterial perfusion (TRAP) sequence following interstitial laser therapy in the first trimester. This was a retrospective cohort study of all consecutive cases of TRAP that underwent interstitial laser therapy at ≤ 14 + 3 weeks' gestation between January 2014 and April 2016. Interstitial laser treatment was performed under ultrasound guidance using a 400-nm Nd:YAG laser fiber. Hospital records were reviewed to ascertain perinatal survival and morbidity. Twelve monochorionic twin pregnancies underwent interstitial laser treatment of the umbilical artery of the acardiac fetus, at a median gestational age of 13 + 5 (interquartile range (IQR), 13 + 4 to 14 + 0) weeks. In all cases, one treatment was sufficient to achieve complete interruption of the perfusion of the acardiac twin. There were no procedure-related complications during or within 48 h after the procedure. In one (8.3%) case, intrauterine death of the pump twin occurred 2 weeks after the intervention. All other cases (91.7%) resulted in a live birth at a median gestational age of 39 + 6 (IQR, 37 + 1 to 41 + 2) weeks and with a median birth weight of 3370 (IQR, 2980-3480) g. No neonatal mortality or serious morbidity occurred. Our results support the use of interstitial laser therapy in the first trimester of pregnancy complicated by TRAP sequence, showing a live birth rate of 92%. The results of a randomized controlled trial, evaluating early vs late intervention in pregnancy with TRAP sequence, are awaited. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Outcome of Pregnancies Diagnosed with TRAP Sequence Prenatally: A Single-Centre Experience

Introduction: Twin reversed arterial perfusion (TRAP) sequence is a phenomenon seen in 1–3% of monochorionic twin pregnancies, where the acardiac fetus is found to have multiple anomalies. The normal pump twin maintains its own perfusion in addition to that of its acardiac co-twin. As a result, if the acardiac twin increases in size, the burden on the pump twin is increased, leading to cardiac failure, hydrops fetalis, polyhydramnios, premature delivery, and perinatal death. The outcome of pregnancy is largely dependent on the growth of the acardiac twin. In view of high perinatal loss, surgical techniques to interrupt the blood flow to the acardiac twin have been evaluated. Methods: We evaluated interstitial laser therapy, which is the main mode of therapy in our unit, of TRAP pregnancies referred over a 5-year period. Interstitial laser was offered if the blood flow in the acardiac twin was found to be persistent at 2 consecutive examinations or if there were cardiac or hydropic changes in the pump twin at the first examination. Results: A total of 18 cases of TRAP were referred during this period and all were counselled regarding fetal therapy if the situation were to deteriorate; 5 couples (27.7%) opted for termination of pregnancy; of the remaining 13, 7 (53.8%) agreed to perform intervention following confirmation of a normal karyotype. Six (85.7%) and 1 (14.3%) lasers were performed in the second and third trimesters, respectively; all 7 had a normal outcome of the pump twin. There were 6/13 (46.2%) in the expectant group who continued the pregnancy with no intervention, with 2 term live births (33.3%). Conclusions: Our study confirms that there is a high risk of spontaneous loss in untreated pregnancies with TRAP, primarily due to polyhydramnios and fetal hydrops. In the pregnancies that underwent interstitial laser, there was a more favourable outcome. Interstitial laser is minimally invasive, safe, and feasible in experienced hands.

Perinatal outcomes and influencing factors following radiofrequency ablation in multiple pregnancies

Objective: To assess the effectiveness of radiofrequency ablation (RFA) in the treatment of multiple pregnancies. Methods: In this retrospective study, 84 cases (total 174 fetuses) of complex monochorionic pregnancies treated with RFA for selective fetal reduction were analyzed. All cases were managed in the Guangdong Women and Children Hospital from January 2015 to January 2018. Indications for offering RFA, details of the procedure and pregnancy outcomes were collected and analyzed. Results: (1)The rate of miscarriage and fetal intrauterine death was 21% (18/84), termination of pregnancy because of fetal malformation or oligohydramnion occurred in 10% (8/84) of cases. Total live birth rate was 69% (58/84) and the gestation age at delivery was (35.0±3.0) weeks. (2) The live birth rate of twin reversed arterial perfusion sequence (TRAPS) was the lowest (6/11), followed by twin to twin transfusion syndrome (TTTS; 66%, 27/41), structural or genetic abnormalities of one fetus in monochorionic twin pregnancy (10/14), triplet pregnancy reduction (4/6) and selective intrauterine growth restriction (sIUGR) (11/12). (3) The live birth rate was 67% (20/30) in stage Ⅲ of TTTS and 7/11 in the stage Ⅳ of TTTS (P>0.05). The average gestational age was (33.6±3.0) weeks in stage Ⅲ of TTTS compared with (36.5±2.4) weeks in the stage Ⅳof TTTS (P<0.05). Conclusions: RFA appears to be a reliable option for selective fetal reduction in monochorionic multiple pregnancies. The indication of RFA is an influencing factor on its pregnancy outcomes. Type Ⅱand type Ⅲ sIUGR may choose this technique as a priority. Compared with stage Ⅲ of TTTS, the live birth rate and the gestation age at delivery in stage Ⅳ of TTTS, there are no significant differences.

Clinical application for pregnacy outcomes of radiofrequency ablation in complex multiple pregnancies

Objective: To investigate the safety and effectiveness of radiofrequency ablation (RFA) for selective fetal reduction in complex multiple pregnancies and analyze factors affecting perinatal outcomes. Methods: This was a retrospective case series of 156 patients undergoing selective fetal reduction by RFA in Provincial Hospital Affiliated to Shandong University from July 22th, 2011 to September 12th, 2018. They were divided into five groups according to surgical indications, including 46 cases in the monochorionic twins discordant for fetal anomalies group, 42 cases in the multiple pregnancies for reducing fetal numbers group, 40 cases in the twin to twin transfusion syndrome (TTTS) group, 24 cases in the selective intrauterine growth restriction (sIUGR) group and 4 cases in the twin reversed arterial perfusion sequence (TRAPS) group. According to the gestational age at surgery, patients were divided into two groups: the gestational age at surgery <20 weeks group (75 cases) and the gestational age at surgery≥20 weeks group (81 cases). According to the cycles of RFA required for surgery, patients were divided into two groups: one cycle group (124 cases) and ≥2 cycles group (32 cases). Basic information of patients, surgical process, postoperative complications and pregnancy outcomes were recorded. The growth and development of survival newborns were also followed up. Factors affecting perinatal outcomes were analyzed. Results: (1) The median gestational age at procedure of 156 patients was 20 weeks (14(+5)- 29(+1) weeks). The median cycles of RFA was 1 cycle (1-3 cycles), of which one cycle accounted for 79.5% (124/156). (2) Eleven (7.1%, 11/156) patients experienced intrauterine fetal death, 27 (17.3%, 27/156) patients miscarried, and the overall survival rate was 75.6% (118/156). Premature birth rate before 34 weeks was 19.5% (23/118). There were 129 neonates. The median gestational age at delivery was 37(+3) weeks (28(+2)- 41(+1) weeks) with a mean birth weight of (2 657±700) g. (3) Analysis of pregnancy outcomes based on surgical indications found that, the gestational age at delivery [38 weeks (30(+1)-41(+1) weeks), 36(+4) weeks (29- 39 weeks), 36(+4) weeks (28(+2)-39(+5) weeks), 38 weeks (31-39(+6) weeks), 38(+3) weeks (30(+4)-38(+4) weeks)] and neonatal birth weight [(2 820±671), (2 435±416), (2 497±843), (2 998±718), (2 517±1 087) g] were significantly different among fetal anomalies group, reducing fetal numbers group, TTTS group, sIUGR group and TRAPS group, respectively (all P<0.05). There were no significant differences in the pregnancy outcomes between gestational age at surgery <20 weeks group and gestational age at surgery ≥20 weeks group, or between one cycle group and ≥2 cycles group, respectively (all P>0.05). Conclusions: RFA is a safe and effective procedure in treating complex monochorionic multiple pregnancies. Surgical indications would affect the gestational age at delivery and neonatal outcomes.

US Evaluation of Twin Pregnancies: Importance of Chorionicity and Amnionicity.

The twin birth rate is increasing in the United States. Twin pregnancies can be dichorionic or monochorionic (MC). MC twins account for 20% of twin pregnancies but 30% of all-cause pregnancy-related complications. This article describes the imaging findings that establish chorionicity and amnionicity. Ideally, these are established in the first trimester when accuracy is high, but they can also be determined later in pregnancy. Complications unique to MC twin pregnancy include twin-twin transfusion syndrome, twin anemia polycythemia sequence, twin reversed arterial perfusion sequence, and selective fetal growth restriction. The US features, staging systems, and management of these complications are reviewed, and the consequences of MC twin demise are illustrated. Ongoing surveillance for these conditions starts at 16 weeks gestation. Monoamniotic (MA) twins are a small subset of MC twins. In addition to all of the MC complications, specific MA complications include cord entanglement and conjoined twinning. Radiologists must be able to determine chorionicity and amnionicity and should be aware of potential complications so that patients may be referred to appropriate regional specialized centers. A proposed algorithm for referral to specialized fetal treatment centers is outlined. Online supplemental material is available for this article. ©RSNA, 2019.

Acardiac Acephalus Twin Pregnancy

Occurrence of acardiac twin is due to twin reversed arterial perfusion sequence (TRAP) occurring early in embryogenesis. There is vascular communication between the twins in monozygotic twins. The vascular communication in acardiac twin is different, in that, the acardiac twin receives blood supply from other twin pump through umbilical artery. The blood in the umbilical artery is mostly deoxygenated. Hence it leads to secondary organ atrophy. Upper body does not develop at all, hence missing heart and head. All the blood supply to the acardiac twin is derived from the pump twin. The acardiac twin develops only lower part of the body or just a mass of tissue. Hence, the mortality for acardiac twin is 100%.&#x0D; Anwer Khan Modern Medical College Journal Vol. 10, No. 1: Jan 2019, P 89-91

OC13.01: Surgical versus expectant management in twin reversed arterial perfusion sequence

OC13.01: Surgical versus expectant management in twin reversed arterial perfusion sequence

OP17.02: Twin reversed arterial perfusion sequence: first trimester intervention

OP17.02: Twin reversed arterial perfusion sequence: first trimester intervention

Safety of radiofrequency ablation for fetal reduction in monochorionic twin pregnancies over 26 weeks of gestation

Objective To investigate the efficacy and safety of radiofrequency ablation for fetal reduction in monochorionic twin pregnancies at gestational age over 26 weeks. Methods A retrospective study was performed based on the clinical data of 51 patients who underwent fetal reduction by radiofrequency ablation in the First Affiliated Hospital of Chongqing Medical University from May 2013 to July 2018. Clinical data including basic information, surgical data (such as ablation duration, power and the number of cycles), perinatal complications and pregnancy outcomes were collected. Differences in pregnancy outcomes were compared between the group with gestational age >26 weeks (n=17, group A) and that ≤26 weeks (n=34, group B) using t-test, rank-sum test and Chi-square test or Fisher's exact test. Results (1) The indications of fetal reduction were malformation in one of the twins, twin-to-twin transfusion syndrome, twin reversed arterial perfusion sequence and selective intrauterine growth restriction [45.1% (23/51), 15.7% (8/51), 19.6% (10/51) and 19.6% (10/51)]. The differences in the proportion of different indications between group A and B were statistically significant [12/17, 1/17, 0/17, 4/17 vs 32.4% (11/34), 20.6% (7/34), 29.4% (10/34), 17.7% (6/34), P=0.009]. Those in the group A required longer operation duration than the group B [M(min-max), 20(7-40) vs 15(3-29) min, Z=2.550, P=0.011]. (2) The gestational age of the 51 patients was (23.7±4.7) weeks (15+1-32+6 weeks), the overall survival rate of the remaining fetuses was 86.3% (44/51) and the preterm birth rate was 50.0% (22/44). The gestational age at operation was (28.9±2.5) weeks (26+1-32+6 week) in group A and (21.1±3.1) weeks (15+1-25+2 weeks) in group B. The survival rate of the remaining fetuses and the preterm birth rate in group A were significantly higher than those in group B [17/17 vs 79.4% (27/34), P=0.046; 12/17 vs 37.0% (10/27), χ2=4.697, P=0.030]. Conclusions Fetal reduction at gestational age >26 weeks, of which the main surgical indication is malformation in one of the twins, may increase the risk of preterm birth, but can improve the overall survival rate of the remaining fetuses without increasing the maternal and infant morbidity. Therefore, radiofrequency ablation is a safe and effective procedure for twin pregnancies >26 weeks of gestation. Key words: Pregnancy, twin; Pregnancy reduction, multifetal; Radiofrequency ablation; Pregnancy trimester, second

Complex multigestational anomalies

The increase in multiple gestation pregnancies has resulted in significant health care implications for both mother and child. Our ability to diagnose and intervene on an at-risk multi-gestation pregnancy has dramatically improved. It is important for the pediatric surgeon to be equipped with a basic fund of knowledge concerning these pregnancies. An understanding of amnionicity and chorionicity will equip the practitioner with the ability to identify which pregnancies are at risk for specific complications. This article highlights multi-gestation pregnancies that are monochorionic (single shared placenta) and can be complicated by twin-twin transfusion syndrome (TTTS), twin reversed arterial perfusion (TRAP) sequence, twin anemia polycythemia sequence (TAPS), or selective fetal intrauterine growth restriction (sIUGR). The risk of fetal demise is significant in these pregnancies. Understanding recommended surveillance and warning signs can alert surgeons to developing complications. Specialized fetal care centers possess the ability to intervene on these pregnancies in utero.

Successive monochorionic twin pregnancies after assisted reproductive technology complicated by repeated twin reversed arterial perfusion sequence.

Successive monochorionic twin pregnancies after assisted reproductive technology complicated by repeated twin reversed arterial perfusion sequence.