The changing Doppler patterns and perinatal outcomes of monochorionic diamniotic twins with selective fetal growth restriction.

OBJECTIVES: To investigate the clinical outcomes and Doppler patterns changes in monochorionic diamniotic (MCDA) twins with selective fetal growth restriction (sFGR). METHODS: We retrospectively analyzed 362 sFGR cases from January 2010 to May 2016 at a single tertiary referral center. The Doppler waveforms of umbilical artery end-diastolic flow were collected, and all neonates were subjected to an early neonatal brain scan. RESULTS: A total of 66/100 (66 %) type I cases were stable, whereas 25/100 (25 %) cases changed to type II and 9/100 (9 %) changed to sFGR complicated twin-twin transfusion syndrome (TTTS). A total of 48.9 % (22/45) sFGR cases were complicated with polyhydramnios and 30.4 % (7/23) sFGR cases were complicated with oligohydramnios, both of which were progressed to sFGR with TTTS. Mild cerebral injury was significantly associated with Doppler flow abnormalities, earlier gestational age at delivery and type of sFGR diagnosis. Severe cerebral injury was significantly associated with gestational age at delivery (31.6 vs. 34.1, p=0.002) and larger birthweight discordance (43.9 vs. 29.3 %, p=0.011). CONCLUSIONS: Doppler patterns in sFGR can gradually change, with important consequences with regard to management and outcomes. Along with abnormal Doppler findings, earlier occurrence of sFGR and delivery are associated with subsequent neonatal cerebral injury.

Maternal hemodynamic evaluation in monochorionic twin pregnancy complicated by twin-to-twin transfusion syndrome treated with fetoscopic laser surgery.

BACKGROUND: Maternal cardiovascular adaptations are amplified in twin pregnancies to support the metabolic request of the feto-placental unit. Few studies have evaluated the maternal hemodynamics changes after routine use of laser surgery in the treatment of twin-twin transfusion syndrome. OBJECTIVE: The aim of our study was to evaluate hemodynamic changes in monochorionic twin pregnancies complicated by twin-twin transfusion syndrome before and after treatment with fetoscopic laser surgery. STUDY DESIGN: A prospective observational study from 2020 to 2022, included monochorionic twin pregnancies complicated with twin-twin transfusion syndrome undergoing laser surgery between 16 and 26 weeks of gestation. To assess placental function and perfusion, uterine artery pulsatility index, hemoglobin, hematocrit, and soluble fms-like tyrosine kinase-1/placental growth factor ratio sampling prelaser and 24 hours postlaser were measured. Echocardiography by a single cardiologist evaluated maternal hemodynamics at presurgery, 24 hours, and 1 week postlaser. Those data were crosswise compared with cardiovascular indices of uncomplicated monochorionic pregnancies recruited at the same gestational age using nonparametric tests. Moreover, we fitted random-intercept linear regression models to investigate maternal hemodynamic changes according to the amount of amniotic fluid drained during laser surgery. RESULTS: Forty-two twin-twin transfusion syndrome pregnancies with a median gestational age of 19.1 (17.4-20.9) weeks and 15 uncomplicated monochorionic pregnancies at the same gestational age were enrolled. Overall survival rate after laser was 72% with delivery at a median gestational age of 31.5 (27-34) weeks. Significant changes in blood chemistry and placental function were observed in the twin-twin transfusion syndrome group, along with alterations in arterial pressure, heart rate, cardiac output, and ventricular strain, eventually aligning with the uncomplicated group's values by 1 week postlaser. The amount of amniodrainage, with a 1000 ml cut-off, did not significantly impact hemodynamic parameters. Lastly, we detected a percentage of laser surgery complications in agreement with international literature and we did not record any maternal procedure-related problems. CONCLUSION: Our analysis highlighted that maternal cardiovascular status in monochorionic twin pregnancy complicated by twin-twin transfusion syndrome was more dynamic and; 1 week after fetoscopic laser ablation of placental anastomosis completed by amniodrainage, maternal hemodynamic parameters restored to values similar to uncomplicated monochorionic twin pregnancies.

Monochorionic Twins: TTTS, TAPS, and Selective Fetal Growth Restriction.

With an increasing incidence of twin gestations, understanding the inherent risks associated with these pregnancies is essential in modern obstetrics. The unique differences in placentation in monochorionic twins leads to unique complications, including twin-to-twin transfusion syndrome, the twin anemia-polycythemia sequence, and selective fetal growth restriction. Not only does the understanding of the monochorionic placenta lead to an understanding of the pathophysiology of the complications of monochorionic twins, but it also has led to the development of highly effective directed fetal therapy via fetoscopic laser coagulation used in twin-to-twin transfusion syndrome.

Selective intrauterine growth restriction without concomitant twin-to-twin transfusion syndrome, natural history, and risk factors for fetal death: A systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the natural history of selective intrauterine growth restriction in monochorionic twin pregnancies based on the Gratacós classification, including progression of, improvement in, or stability of umbilical artery Dopplers and progression to twin-to-twin transfusion syndrome or twin anemia polycythemia syndrome. We also aimed to investigate risk factors for smaller twin demise. DATA SOURCES: A systematic search was performed to identify relevant studies published in English up to June 2022 using the databases PubMed, Scopus, and Web of Science STUDY ELIGIBILITY: We used retrospective and prospective studies published in English that reported on selective intrauterine growth restriction without concomitant twin-to-twin transfusion syndrome. STUDY APPRAISAL AND SYNTHESIS METHODS: Articles that investigated selective intrauterine growth restriction progression and outcomes by umbilical artery Doppler end-diastolic flow (Gratacós classification) were included. Type I included selective intrauterine growth restriction cases with positive end-diastolic flow, type II included those cases with persistently absent end-diastolic flow, and type III included cases with intermittent absent or reversed end-diastolic flow. Pregnancies in which a diagnosis of twin-to-twin transfusion syndrome or twin anemia polycythemia sequence was made before the diagnosis of selective intrauterine growth restriction were not included in the analysis. A random effects model was used to pool the odds ratios and the corresponding 95% confidence intervals. Heterogeneity was assessed using the I2 value. RESULTS: A total of 17 studies encompassing 2748 monochorionic pregnancies complicated by selective intrauterine growth restriction were included in the analysis. The incidence of stable, deteriorating, or improving umbilical artery Dopplers in type I cases was 68% (95% confidence interval, 26-89), 23% (95% confidence interval, 7-40), and 9% (95% confidence interval, 0.0-100), respectively. In type II cases, the incidence was 40% (95% confidence interval, 18-81), 50% (95% confidence interval, 23-82), and 10% (95% confidence interval, 4-37), respectively, and in type III cases, the incidence was 55% (95% confidence interval, 2-99), 23% (95% confidence interval, 9-43), and 22% (95% confidence interval, 6-54), respectively. The risk for progression to twin-to-twin transfusion syndrome was comparable between type I (7%) and type III (9%) cases and occurred in 4% (95% confidence interval, 0-67) of type II cases with no significant subgroup differences. Progression to twin anemia polycythemia syndrome was highest in type I cases (12%) and comparable between type II (2%) and III (1%) cases with no significant subgroup differences. Risk factors for smaller twin demise were earlier gestational age at diagnosis (mean difference, -2.69 weeks; 95% confidence interval, -4.94 to -0.45; I2, 45%), larger intertwin weight discordance (mean difference, 34%; 95% confidence interval, 1.35-5.38; I2, 28%), deterioration of umbilical artery Dopplers for each of type II and III cases (odds ratio, 3.05; 95% confidence interval, 1.36-6.84; I2, 24%; and odds ratio, 4.5; 95% confidence interval, 2.31-8.77; I2, 0.0%, respectively), and absent or reversed ductus venosus a-wave for each of type II and III cases (odds ratio, 3.35; 95% confidence interval, 2.28-4.93; I2, 0.0%; and odds ratio, 2.36; 95% confidence interval, 1.08-5.13; I2, 0.0%, respectively). Progression to twin-to-twin transfusion syndrome was not significantly associated with smaller twin demise for each of type II and III selective intrauterine growth restriction cases. CONCLUSION: These findings improve our understanding of the natural history of the types of selective intrauterine growth restriction and of the predictors of smaller twin demise in type II and III selective intrauterine growth restriction cases. The current data provide vital counseling points and support the need for modifications of the current selective intrauterine growth restriction classification system to include the variations in umbilical artery and ductus venosus Dopplers to better identify a cohort that might benefit from fetal intervention for which future multicenter prospective randomized trials are needed.

Management of twin reversed arterial perfusion sequence: eight cases over 13 years.

BACKGROUND: Twin reversed arterial perfusion (TRAP) sequence is a rare condition that affects primarily monozygotic monochorionic twin pregnancies in which a normal twin acts as a pump (donor) for an acardiac recipient (perfuse) twin. OBJECTIVE: We report our experience over the last 13 years at a tertiary health care center. DESIGN: Descriptive, retrospective case series SETTING: Tertiary health care center PATIENTS AND METHODS: All TRAP cases managed between the years 2009 and 2022 at our Fetal Diagnosis and Therapy Center were included. Data recorded included demographic and clinical information which was used to generate descriptive data. Patients were managed by a multidisciplinary team with variable interventions. MAIN OUTCOME MEASURE: Survival of normal twin SAMPLE SIZE: Eight RESULTS: Eight pregnant women with TRAP syndrome were managed at our center during that period. One was monozygotic monochorionic and the others were monochorionic diamniotic. Median maternal age at presentation was 27 years and median gestational age at diagnosis was 23 weeks. All were diagnosed with ultrasound (US) imaging. Three were managed with bipolar ligation of the cord of the acardiac twin under general anesthesia, one US-guided (single port) and 2 fetoscopic (2 ports) with a median operative time of 39 minutes. The last five cases were managed with US-guided radiofrequency ablation (RFA) under local anesthesia, one needed 2 sessions, 1 week apart. The median duration of the RFA procedure was 23 minutes. There were no complications and all had viable normal babies born at a median of 32 weeks of gestation (6 C-section, 2 spontaneous membrane rupture). CONCLUSIONS: Acardiac twin cord ligation and RFA are feasible and safe options with excellent outcome for TRAP syndrome. RFA may be preferable owing to its less invasiveness under local anesthesia. LIMITATIONS: None, given the rarity of the disease and the study design. CONFLICT OF INTEREST: None.

Guideline No. 440: Management of Monochorionic Twin Pregnancies.

OBJECTIVE: This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies. TARGET POPULATION: Women with monochorionic twin or higher order multiple pregnancies. BENEFITS, HARMS, AND COSTS: Implementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality. These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins. EVIDENCE: Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials. VALIDATION METHODS: The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations). INTENDED AUDIENCE: Maternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies. TWEETABLE ABSTRACT: Canadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin. SUMMARY STATEMENTS: RECOMMENDATIONS.

Pulmonary valve stenosis in a recipient twin in twin-to-twin transfusion syndrome with successful balloon valvuloplasty after birth: a case report.

BACKGROUND: Pulmonary stenosis (PS) is a congenital heart diseases (CHDs) with a spectrum of stenosis. Monochorionic (MC) twins are at increased risk of CHDs, especially acquired CHDs in twin-twin transfusion syndrome (TTTS). PS/Pulmonary atresia (PA) is a rare coincidence with TTTS. MC twin pregnancies have increased in last decades due to increasing in maternal age and extensive use of assisted reproductive technologies. Therefore, attention to this group is important for heart abnormalities, especially in twins with TTTS. Multiple cardiac abnormalities in MC twins with TTTS are to be expected due to cardiac hemodynamic changes and may be eliminated by Fetoscopic laser photocoagulation treatment. Prenatal diagnosis of PS is necessary given the importance of treatment after birth. CASE PRESENTATION: We here present a case of coexistence of TTTS with PS in a growth restricted recipient twin who successfully treated with balloon pulmonary valvuloplasty in neonatal period. Also, we detected infundibular PS after valvuloplasty that treated with medical therapy (propranolol). CONCLUSIONS: It is important to detect acquired cardiac abnormalities in MC twins with TTTS, and follow them up after birth to determine the need of intervention in neonatal period.

Subclassification of fetal growth restriction type IIa vs type IIb applied to twin-twin transfusion syndrome.

BACKGROUND: Subclassification of monochorionic twins with selective fetal growth restriction type II into IIa vs IIb has been proposed because of differing neonatal survival outcomes of the fetus with growth restriction after laser surgery based on preoperative Doppler findings in the middle cerebral artery and ductus venosus. There is substantial clinical overlap between selective fetal growth restriction and twin-twin transfusion syndrome. OBJECTIVE: This study aimed to compare donor twin neonatal survival after laser surgery in cases of twin-twin transfusion syndrome with concomitant donor fetal growth restriction type IIa vs IIb. STUDY DESIGN: This was a retrospective study of monochorionic multifetal pregnancies treated with laser surgery for stage III twin-twin transfusion syndrome and concomitant donor twin fetal growth restriction type II at a referral center from 2006 to 2021. Donor fetal growth restriction type II was defined as having an estimated fetal weight <10th percentile with persistent absent and/or reversed end-diastolic velocity in the umbilical artery. Moreover, patients were subclassified as type IIa (having normal middle cerebral artery peak systolic velocities and ductus venosus Doppler waveforms) vs type IIb (having middle cerebral artery peak systolic velocities ≥1.5 multiples of the median and/or ductus venosus with persistent absent or reversed atrial systolic flow). This study compared 30-day neonatal survival of the donor twin by fetal growth restriction type IIa vs IIb using logistic regression to adjust for relevant preoperative covariates (P<.10 in bivariate analysis). RESULTS: Of 919 patients who underwent laser surgery for twin-twin transfusion syndrome, 262 had sstage III donor or donor and recipient twin-twin transfusion syndrome; of these patients, 189 (20.6%) had concomitant donor fetal growth restriction type II. Moreover, 12 patients met the exclusion criteria, yielding 177 patients (19.3%) who composed the study cohort. Patients were subclassified as donor fetal growth restriction type IIa (146 [82%]) vs type IIb (31 [18%]). Donor neonatal survival for fetal growth restriction type IIa vs IIb was 71.2% vs 41.9% (P=.003). Recipient neonatal survival did not differ between the 2 types (P=1.000). Patients classified with twin-twin transfusion syndrome and concomitant donor fetal growth restriction type IIb were 66% less likely to have neonatal survival of the donor after laser surgery (adjusted odds ratio, 0.34; 95% confidence interval, 0.15-0.80; P=.0127). The logistic regression model was adjusted for gestational age at the procedure, estimated fetal weight percent discordance, and nulliparity. The c-statistic was 0.702. CONCLUSION: For patients with stage III twin-twin transfusion syndrome and concurrent donor fetal growth restriction with persistent absent or reversed end-diastolic velocity in the umbilical artery (ie, fetal growth restriction type II), subclassification into fetal growth restriction type IIb based on elevated middle cerebral artery peak systolic velocity and/or abnormal ductus venosus flow in the donor conveyed poorer prognosis. Although donor neonatal survival after laser surgery was lower for patients with stage III twin-twin transfusion syndrome with donor fetal growth restriction type IIb than patients with stage III twin-twin transfusion syndrome with donor fetal growth restriction with type IIa, laser surgery for fetal growth restriction type IIb in the setting of twin-twin transfusion syndrome (as opposed to pure selective fetal growth restriction type IIb) still allows for the possibility of dual survivorship and should be offered with shared decision-making when counseling patients on management options.

Fetal anemia in monochorionic twins: a review on diagnosis, management, and outcome.

INTRODUCTION: Monochorionic twins may develop fetal anemia when blood is unequally distributed via the placental vascular anastomoses. This review focuses on the causes of fetal anemia in complicated monochorionic twins and highlights the differences in management and outcome. AREAS COVERED: Fetal anemia can occur in the context of twin anemia polycythemia sequence (TAPS), chronic twin-twin transfusion syndrome (TTTS) and acute peripartum TTTS, and in cotwins after single fetal demise. Diagnosis of fetal anemia is based on abnormal Doppler ultrasound measurements. Management options include fetoscopic laser surgery, intrauterine blood transfusion, or expectant management, depending on the type of complication and the severity of the disease. In all complications, fetal anemia may lead to perinatal mortality, neonatal morbidity, severe cerebral injury, and long-term neurodevelopmental impairment. In TAPS specifically, anemic donors may also show bilateral deafness. EXPERT OPINION: Knowledge on the diagnosis and optimal treatment in TTTS is nowadays widespread, but caregivers often fail to distinguish TAPS from acute peripartum TTTS at birth. A full blood count including reticulocyte count is required, and placental dye injection is extremely helpful to reach the correct diagnosis and establish the optimal management.

Twin Anemia-Polycythemia Sequence (TAPS): From Basic Research to Clinical Practice.

Twin pregnancy is associated with an increased risk of perinatal and maternal complications, and early establishment of the chorionicity type defines this risk. In monochorionic (MC) pregnancies, the fetuses share the same placental mass and exhibit vascular anastomoses crossing the intertwin membrane, and the combination and pattern of anastomoses determine the primary clinical picture and occurrence of future complications. Twin Anemia-Polycythemia Sequence (TAPS) was first described in 2006 after fetoscopic laser surgery in twin-to-twin transfusion syndrome (TTTS) twins, and in 2007, the first spontaneous cases were reported, recognizing TAPS as an individualized vascular identity in fetofetal transfusion syndromes. There are two types of TAPS: spontaneous (3-5%) and iatrogenic or postlaser (2-16%). TAPS consists of small diameter arteriovenous anastomoses (<1 mm) and low-rate, small-caliber AA anastomoses in the absence of amniotic fluid discordances. There are certain antenatal and postnatal diagnostic criteria, which have progressively evolved over time. New, additional secondary markers have been proposed, and their reliability is being studied. The best screening protocol for TAPS in MC twins is still a matter of debate. This review provides a survey of the relevant literature on the epidemiology, vascular pathophysiology, underlying hemodynamic factors that regulate mismatched vascular connections, and diagnostic criteria of this condition. The aim is to increase awareness and knowledge about this recently identified and frequently unrecognized and misdiagnosed pathology.

Pregnancy outcomes following early fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome at 16 weeks' gestation.

BACKGROUND: Ample evidence supports fetoscopic laser photocoagulation of placental anastomoses as a first-line treatment for twin-to-twin transfusion syndrome, but little is known about the outcomes following procedures conducted in the early second trimester. OBJECTIVE: This study aimed to evaluate perinatal outcomes following early fetoscopic laser placental photocoagulation performed for twin-to-twin transfusion syndrome at 16 weeks' gestation. STUDY DESIGN: This retrospective review included monochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome necessitating fetoscopic laser photocoagulation at a single tertiary center from 2012 to 2021. The 2 cohorts were defined as cases undergoing laser surgery at 16+0/7 to 16+6/7 weeks' gestation (early laser group) and those undergoing laser surgery ≥17 weeks' gestation (standard laser group), respectively. Primary outcomes included rates of immediate chorioamniotic membrane separation, preterm premature rupture of membranes, and clinical chorioamnionitis. Secondary outcomes included twin survival rates at birth and 30 days of life. Outcomes were compared between cohorts with a P value of <.05 denoting statistical significance. RESULTS: A total of 343 cases were included (35 early laser participants and 308 standard laser participants). The early laser group typically had higher Quintero staging at the time of the procedure. Following intervention, the early laser group had significantly higher rates of chorioamniotic separation than the standard laser group (34.3% vs 1.3% of cases; P<.001) and higher rates of preterm prelabor rupture of membranes (45.7% vs 25.0%; P=.009) and chorioamnionitis (11.4% vs 1.3%; P=.005). Even after adjustment for higher Quintero staging in the early laser group, twin survival was not significantly different between study groups. CONCLUSION: Early laser surgery for twin-to-twin transfusion syndrome performed at 16 weeks' gestation is associated with significantly higher rates of chorioamniotic separation, preterm rupture of membranes, and chorioamnionitis. However, twin survival does not seem to be negatively impacted following early laser surgery.

Perinatal outcomes of pregnancies with twin-anemia polycythemia sequence complicating twin-to-twin transfusion syndrome using different twin-anemia polycythemia sequence diagnostic criteria.

OBJECTIVE: To investigate whether the presence of twin-anemia polycythemia sequence (TAPS) with twin-to-twin transfusion syndrome (TTTS) or post-laser TAPS would change outcomes using different TAPS diagnostic criteria. METHODS: TTTS cases undergoing laser surgery between 2012 and 2020 were included. Groups included pre-laser TTTS-only compared to TTTS + TAPS, and no post-laser TAPS compared to post-laser TAPS. Three prenatal TAPS diagnostic criteria were used: group A: middle cerebral artery-peak systolic velocity (MCA-PSV) > 1.5 MoM in one twin and <1 MoM in the other twin, group B: inter-twin MCA-PSV difference >1 MoM, and group C: inter-twin MCA-PSV difference >0.5 MoM. Perinatal outcomes including survival and severe cerebral injury were investigated. RESULTS: 174 laser procedures were included. TTTS + TAPS cases were 16 in group A, 17 in group B, and 29 in group C. Post-laser TAPS cases were 11 in group A, 6 in group B, and 12 in group C. There were no differences in preoperative, operative variables and outcomes including survival and severe cerebral injury between groups using all three TAPS diagnostic criteria. The incidence of TTTS + TAPS was highest in group C (16.7%), then group B (9.8%), followed by group A (9.2%). The incidence of post-laser TAPS was highest in group C (9%), then group A (8.3%), followed by group B (4.5%). CONCLUSION: Presence of TAPS complicating TTTS and presence of post-laser TAPS do not seem to be associated with worse perinatal outcomes including postnatal-ultrasound detected cerebral injury using three different TAPS criteria. Collaborative studies are needed to investigate the validity and the performance of different TAPS criteria.

Neonatal management and outcome in complicated monochorionic twins: What have we learned in the past decade and what should you know?

Monochorionic (MC) twin pregnancies are at increased risk of neonatal morbidity and mortality due to the shared placenta with vascular connections that can give rise to various complications, including twin-twin transfusion syndrome, twin anemia polycythemia sequence (TAPS), selective fetal growth restriction, and other hematological imbalances at birth. Each complication presents its own challenges and considerations in the neonatal period. Measurement of hemoglobin levels and reticulocyte count is required to establish a correct diagnosis. Placenta dye injection is needed to properly distinguish between the various conditions. Risk factors for adverse outcome in MC twins include prematurity, severe cerebral injury, and the type of MC pregnancy complication. We, therefore, recommend cerebral ultrasound examinations in all complicated MC twins at birth to rule out a severe brain injury. Lastly, we strongly encourage screening for hearing loss using automated auditory brainstem response in all spontaneous TAPS donors to prevent permanent speech development delay.

Long-term follow-up of complicated monochorionic twin pregnancies: Focus on neurodevelopment.

Monochorionic twin pregnancies have an increased risk of morbidity and mortality. Due to the advancements in screening and treatment strategies, mortality rates have decreased. Improving survival rates demands a shift in scope toward long-term outcomes. In this review, we focus on neurodevelopmental outcome in survivors from complicated monochorionic twin pregnancies, including twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), acute peripartum TTTS, acute perimortem TTTS, selective fetal growth restriction (sFGR) and monoamnionicity. Our aim is to provide an overview of the current knowledge on the long-term outcome in survivors, including psychomotor development and quality of life, and provide recommendations for future research and follow-up programs.

Twin-to-twin transfusion syndrome: Controversies in the diagnosis and management.

In twin-to-twin transfusion syndrome (TTTS) communicating placental vessels on the chorionic plate between the donor and recipient twins are responsible for the chronic imbalance of blood flow. Evidence demonstrates that fetoscopic laser ablation is superior to serial amnioreductions in terms of survival and neurological outcome for stages II-IV TTTS. However, the optimal management of stage I TTTS remains poorly understood. It is well established that all chorionic plate anastomoses should be closed by laser ablation. Compared to the selective laser method, the Solomon technique yields a significant reduction of recurrent TTTS and post-laser twin anemia polycythemia sequence (TAPS). Over the past 25 years, survival rates after fetoscopic laser surgery have significantly increased. High volume centers report up to 70% double survival and at least one survivor in >90% cases. In this review, we discuss the controversies in the diagnosis and management of TTTS, especially, the optimal management in stage I cases, very early or late diagnosis, and the optimal laser technique. Furthermore, we will discuss a stage-related outcome after laser surgery and examine whether it is necessary at all to distinguish between stages I and II. Finally, the optimal timing as well as mode of delivery after TTTS laser treatment will be discussed.

Pathophysiology, diagnosis, and management of twin anemia polycythemia sequence in monochorionic multiple gestations.

Twin anemia polycythemia sequence (TAPS) is a consequence of unequal sharing of red blood cells between monochorionic twins resulting in anemia in the donor and polycythemia in the recipient twin. Prenatally TAPS can occur spontaneously or complicate incomplete laser surgery for twin transfusion syndrome. While there may be clinical overlap with twin transfusion syndrome or selective fetal growth restriction, diagnosis relies on Doppler measurement of middle cerebral artery peak systolic velocities. Significantly discordant velocities are diagnostic, while severity staging is based on signs of cardiovascular compromise. Conservative management, fetoscopic laser coagulation, selective twin reduction, fetal blood and exchange transfusion, and delivery may be selected guided by the gestational age of diagnosis, the severity of the condition, the likelihood of success, and the patients' priorities. Prenatal curative treatment that minimizes the risk for prematurity and residual morbidity at birth is most likely to offer the greatest short-term and long-term benefits.

Amyoplasia in monochorionic monozygotic pregnancy following interstitial laser.

Amyoplasia is a specific form of arthrogryposis, without any genetic cause. Six to ten percent of amyoplasia cases are one of the monozygotic twins, with the other twin being normal. Failure of maturation of anterior horn cells (AHCs) due to ischemic injury has been postulated as the primary pathological change, leading to arrest in the development of muscle fibers supplied by the affected AHCs with the typical limb positioning seen in amyoplasia. Twin-to-twin transfusion syndrome (TTTS) is an important risk factor for ischemic injury in monozygotic twin pregnancies. We present a case of monochorionic diamniotic twin pregnancy with features of TTTS at 12 weeks who underwent interstitial laser followed by the development of lower limb akinesia in the surviving fetus. Possible causes of amyoplasia are discussed.

Evaluation of the new expert consensus-based definition of selective fetal growth restriction in monochorionic pregnancies.

OBJECTIVE: To compare the outcomes of a cohort of monochorionic pregnancies with selective fetal growth restriction (sFGR) diagnosed according to the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) definition published in 2015 with a cohort considered as sFGR according to new expert consensus-based diagnostic parameters published in 2019. METHODS: This was a retrospective study, conducted between January 1st 2010 and July 30th 2019. We reviewed the medical records of all the monochorionic pregnancies followed in our center including perinatal outcomes. Pregnancies complicated by fetal anomalies, infection, twin-twin transfusion syndrome, twin anaemia-polycythemia sequence and twin reversed arterial perfusion sequence were excluded. Patients were grouped according to the 2015 ISUOG definition into: normal (Group 1), sFGR (Group 2), and monochorionic pregnancies with abnormal growth that did not fulfill the full criteria for sFGR (Group 3). After the initial classifications were made, an additional group, was created, including all pregnancies reclassified as sFGR according to the 2019 expert consensus parameters (Group 4). RESULTS: During the study period, 291 monochorionic pregnancies were followed in our center, 132 of whom were eligible for inclusion in the final analysis. The prevalence of sFGR increased from 17.4% to 26.5% after applying the expert consensus-based parameters to the study population. Compared to group 1, group 2 had higher rates of emergency cesarean, neonatal intensive care admissions, invasive and noninvasive ventilation, surfactant use, metabolic disorders and lower gestational ages at birth. In contrast, the neonatal outcomes of Groups 1 and 4 were not significantly different. CONCLUSION: When the 2019 consensus-based diagnostic parameters for sFGR were applied to our study population, the number of sFGR cases increased by over 50%, without any improvements in perinatal outcomes. Larger prospective studies are needed to examine the potential clinical implications of these new parameters for sFGR in monochorionic pregnancies.

Monochorionic diamniotic twin pregnancies.

About 1 in 5 twin pregnancies are monochorionic diamniotic. In these twins, transfusion imbalances may develop because of the vascular anastomoses that are invariably present. The most severe imbalance is twin-twin transfusion syndrome, which presents as a significant amniotic fluid difference diagnosed on ultrasound scan, usually before 26 weeks. Another transfusion imbalance is twin anemia polycythemia sequence, which is a severe hemoglobin difference occurring mainly after 26 weeks in previously uncomplicated pregnancies. Fetoscopic laser coagulation of the anastomoses addresses the cause of these transfusion imbalances. Beside transfusion imbalances, the monochorionic placenta may be unevenly divided, or one part may be dysfunctional, leading to an intertwin growth difference of more than 20%. Here, laser ablation of the anastomoses will usually not cure the problem, but it aims to protect the appropriately growing twin if the growth-restricted cotwin dies. In monochorionic twins, structural anomalies are twice as common as in singleton pregnancies, probably because of a teratogenic effect of the embryonic splitting or because of transfusion imbalances. In contrast, chromosomal anomalies seem less common, possibly because they more likely result in an early demise. Selective reduction is feasible in monochorionic pregnancies but carries increased risks of loss, miscarriage, and early birth than selective reduction in a dichorionic setting. Finally, if one monochorionic twin dies spontaneously, its cotwin may acutely exsanguinate into the demised cotwin, which may result in the loss of both twins or brain damage in the surviving twin. This update addresses the pathophysiology, diagnosis, and management of these common complications in monochorionic diamniotic twin pregnancies.

Fetal and neonatal brain lesions following laser ablation for twin-to-twin-transfusion-syndrome as detected by pre- and post-natal brain imaging.

OBJECTIVE: To determine the rate of and risk factors for fetal and neonatal brain lesions following laser ablation for twin-to-twin transfusion syndrome (TTTS). METHODS: A retrospective cohort study of 83 women with monochorionic twin pregnancies who underwent ablation for TTTS at a single tertiary hospital. Post-laser survivors were followed-up with fetal neurosonogram every 2 weeks and fetal brain MRI at 28-32 weeks of gestation; post-natal brain imaging included neurosonogram. Cases with pre- and post-natal brain lesions were compared to those without. RESULTS: 153 fetuses survived the immediate post-laser period and underwent brain imaging. Of these, 17 (11.11%) exhibited brain lesions on prenatal imaging studies, and 36 (32.4%) on post-natal ultrasound. Later gestational age (GA) at the time of ablation (23.0 vs. 21.4 weeks, p = 0.0244), post-laser twin-anemia-polycythemia-sequence (TAPS) (29.41% vs. 9.56%, p = 0.035) and birthweight discordancy (30% vs. 9%, p = 0.0025) were associated with prenatal brain lesions. Earlier GA at delivery (31.0 weeks vs. 32.2, p = 0.0002) and post-laser TAPS (25% vs. 9.33%, p = 0.038) were associated with post-natal brain lesions. CONCLUSIONS: Survivors of ablation for TTTS are at risk for brain lesions, which can be detected prenatally. Incorporation of neurosonogram and fetal brain MRI into the routine surveillance of such pregnancies should be considered.