Monochorionic Twin Pregnancies Research Articles

Perinatal outcome in monochorionic twin pregnancies after selective fetal reduction using radiofrequency ablation.

To study the perinatal outcomes in women with complicated monochorionic twin pregnancies undergoing selective fetal reduction using radiofrequency ablation (RFA). This retrospective study included 44 patients with monochorionic twin pregnancies, between 14 and 28weeks of pregnancy, who underwent RFA for selective fetal reduction. Perinatal and maternal outcomes and procedure-related complications were analyzed. The procedure was technically successful in all 44 cases. Indications for selective fetal reduction included twin-to-twin transfusion syndrome (52.3%), twin reversed arterial perfusion (20.5%), twins discordant for anomaly (15.9%), and selective fetal growth restriction (11.4%). Median gestational age at procedure was 222/7 weeks (range 14-266/7 ). Live birth rate was 77.3% with three neonatal deaths; so overall survival was 70.5%. Median procedure-to-delivery interval was 123/7 weeks (range 24/7 -23). There were eight losses before 24weeks of pregnancy, which included two co-twin deaths. Median gestational age at delivery was 35weeks (interquartile range 321/7 -37weeks). The preterm delivery rate was 66.7% (24/36) and preterm prelabor rupture of membranes (PPROM) occurred in 22.7% (10/44) of patients. Selective fetal reduction using RFA is safe and effective in complicated monochorionic pregnancies. However, the rates of PPROM and preterm delivery remain high.

Differentiation between TTTS Stages I vs II and III vs IV does not affect probability of double survival after laser therapy

To compare the perinatal outcome of monochorionic twin pregnancies with twin-twin transfusion syndrome (TTTS), according to the disease severity, defined using Quintero staging, after treatment with fetoscopic laser surgery. This was a single-center study of 1020 consecutive cases with severe TTTS, which were treated with fetoscopic laser surgery. During the study period from January 1995 to March 2013, the participants were included at a mean ± SD gestational age of 20.8 ± 2.2 weeks. Perinatal survival analysis, including the rates of double survival and survival of at least one fetus, was undertaken according to the Quintero staging system. For blockwise comparisons of data, the whole population was divided into five chronologically consecutive study subgroups of 200 patients in each of the first four subgroups and 220 in the last one. For the entire study population with known outcome (n = 1019), the rate of pregnancy with double fetal survival was 69.0% (127/184) in Stage-I, 71.4% (257/360) in Stage-II, 55.4% (236/426) in Stage-III and 51.0% (25/49) in Stage-IV TTTS cases. At least one twin survived in 91.3% (168/184) of pregnancies with Stage-I, 89.7% (323/360) of those with Stage-II, 83.1% (354/426) of those with Stage-III and 77.6% (38/49) of those with Stage-IV TTTS. The rates of double survival and survival of at least one fetus were both significantly higher in Stage-II TTTS compared with those in Stage-III TTTS cases (P < 0.001 and P = 0.011, respectively). Survival rates between pregnancies with Stage-I vs Stage-II TTTS and between those with Stage-III vs Stage-IV TTTS were not significantly different. Therefore, we combined pregnancies with Stage-I or Stage-II TTTS, and those with Stage-III or Stage-IV TTTS. The double survival rate was 70.6% (384/544) in combined Stage-I and Stage-II vs 54.9% (261/475) in combined Stage-III and Stage-IV TTTS cases (P < 0.001). At least one twin survived in 90.3% (491/544) of pregnancies with Stage-I or Stage-II TTTS vs 82.5% (392/475) in those with Stage-III or Stage-IV TTTS (P < 0.001). The double survival rate increased between the first and the last consecutive study subgroups from 59.8% (55/92) to 75.0% (96/128) (adjusted odds ratio (aOR)linear trend , 1.26 (95% CI, 1.01-1.56); P = 0.037) in pregnancies with Stage-I or Stage-II TTTS and from 41.7% (45/108) to 62.0% (57/92) (aORlinear trend , 1.21 (95% CI, 0.98-1.50); P = 0.082) in those with Stage-III or Stage-IV TTTS. Double survival rate was the lowest for Stage-III cases in which the donor twin was affected by severely abnormal Doppler findings (45.4% (64/141)). Double survival and survival of at least one fetus in monochorionic twin pregnancies with TTTS were related significantly to Quintero stage. However, our data show that the differentiation between Stages I vs II and Stages III vs IV does not have any significant prognostic implication for perinatal survival. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Outcomes of fetoscopic laser surgery for twin-to-twin transfusion syndrome between 26 and 27 weeks of gestation in Japan.

The purpose of this study was to investigate the outcomes of fetoscopic laser photocoagulation (FLP) for twin-to-twin transfusion syndrome (TTTS) in Japan. The retrospective cohort study (2012-2018) was conducted in monochorionic twin pregnancies that underwent FLP for TTTS between 26 and 27 weeks from 2012 to 2018. The perioperative data, maternal complications, gestational age (GA) at delivery, neonatal complications, and survival of infants at 28 days of age were analyzed. At term-equivalent age, severe neurological complications were identified by imaging study. Of 644 patients, 28 (4.3%) underwent FLP between 26 and 27 weeks, and 26 were analyzed. FLP procedures were technically successful in all cases. There were no cases of major maternal complications after surgery. Preterm rupture of membranes occurred in 34.6% of cases, and the mean GA at delivery was 33.2 ± 3.1 weeks. The survival of both twins was found in 23 (88.4%) cases, and the perinatal survival rate of at least one twin at 28 days of age was 100%. Severe neurological complications were found in six (12.2%) cases out of 49. FLP for TTTS between 26 and 27 weeks provided a good prognosis and caused no major maternal complications. However, severe neurological findings were found in 12% of infants.

Second-trimester abdominal circumference discordance and adverse perinatal outcomes in monochorionic twins

Objective The perinatal outcomes in second-trimester abdominal circumference (AC) discordant twins are yet to be established. The aim of this study was to ascertain perinatal risks associated with second-trimester AC discordance in monochorionic (MC) twins. Method We conducted a retrospective study of all MC twin pregnancies over a 7-year period. Intertwin AC discordance at 14–26 gestational weeks was analyzed in relation to Doppler abnormalities, obstetric complications, and perinatal adverse outcomes. Results A total of 246 MC twin pregnancies were included in the analysis. The smaller twins of second-trimester AC discordant pairs were at increased prevalence of abnormal umbilical artery flow (50% versus 24%, p < .001) and low positive A wave of ductus venous flow (24% versus 9%, p = .002). The second-trimester AC discordant twins were at increased risk of oligohydramnios in smaller twin (OR = 2.44, 95% CI = 1.37–4.32, p < .01), cardiomegaly in larger twin (OR = 2.95, 95% CI = 1.01–8.60, p < .05), birth weight of either twin below the 10th percentile for gestational age (OR = 5.56, 95% CI = 2.67–11.59, p < .001), birth weight discordance > 25% (OR = 9.41, 95% CI = 4.46–19.87, p < .001), IUFD (OR = 3.26, 95% CI = 1.76–6.05, p < .001), and severe neonatal morbidity (OR = 1.83, 95% CI = 1.03–3.26, p < .05). The intact survival rate in discordant and concordant twin pairs was 70% and 89%, respectively (p < .001). Conclusions Early and increase fetal surveillance of the second-trimester AC discordant twins should be utilized to establish perinatal risks, thus allowing prenatal care to improve.

Call to action: long‐term neurodevelopment in monochorionic twins

Call to action: long‐term neurodevelopment in monochorionic twins

Fused yolk sacs in a case of forked umbilical cord in monochorionic diamniotic twin pregnancy: sonoembryological implications

Forked cord (FC), which presents as a fused insertion of two umbilical cords into a monochorionic placenta, is a rare entity, especially in monochorionic diamniotic (MCDA) twin pregnancies. Herein, we describe a case of a MCDA pregnancy with FC, which showed characteristic findings on first-trimester ultrasound examination. A healthy 29-year-old nulliparous woman presented at 8 weeks of gestation following a positive result on pregnancy self-testing. Transvaginal ultrasound revealed two fetuses with active heartbeats and both had their own amniotic membrane, suggesting a MCDA pregnancy (Figure 1a). Noteworthy was that the two yolk sacs were completely fused (Figure 1b) and the connecting stalks, which are the site of the future umbilicus, were located in close proximity to one another (Figure 1c). On transabdominal ultrasound screening at 16 weeks of gestation (Figure 2a), FC was diagnosed but no other abnormalities were detected. The pregnancy course was uneventful and healthy female babies, weighing 2285 g and 2345 g, were born vaginally at 36 weeks. The umbilical and placental inspection revealed that each umbilical cord had two arteries and one vein, which fused near the placental surface, where the amniotic membranes divided the amniotic cavities (Figure 2b). Most cases of previously reported FC were observed in monochorionic monoamniotic (MCMA) twin pregnancies, which were frequently accompanied by an acardiac twin1, 2. Thomas et al. was the first to report an antenatally diagnosed case of FC in an otherwise uncomplicated MCDA pregnancy, in which FC was recognized at 30 weeks, and healthy infants (weighing 2460 g and 2490 g) were delivered at 35 weeks3. Frisch et al. reported a case of FC in a MCMA pregnancy diagnosed at 10 weeks, in which the twin pair (weighing 1169 g and 935 g) was delivered at 29 weeks because of abnormal fetal heart rate patterns4. In our case, which is the third report in the literature of liveborn twins with prenatal diagnosis of FC, the unique findings were the fused yolk sacs, with the amniotic membranes dividing the two fetuses as early as 8 weeks of gestation, in addition to the closely located connecting stalks. From an embryological viewpoint, the folding of the embryo and the expansion of the amniotic cavity, which bring the connecting stalk and yolk sac together to form the umbilical cord, occur after 9 weeks of gestation5. We postulate that our findings at 8 weeks of the fused yolk sacs and the closely located connecting stalks might be forecasting subsequent FC, even when the amniotic membranes dividing two embryos are visualized. As for the blood volume balance between the twins, we agree with the speculation of Thomas et al. and Frisch et al. that a fenestration between the two umbilical vein walls may have had a protective effect on the hemodynamic status of the twins3 and that FC itself in MCMA and MCDA pregnancies does not necessarily cause adverse perinatal outcome4. Our first-trimester findings provide new insights into sonoembryology, especially in relation to umbilical cord development from connecting stalks.

SFlt-1, Not PlGF, Is Related to Twin Gestation Choronicity in the First and Third Trimesters of Pregnancy.

Background: Preeclampsia occurs more often in dichorionic than in monochorionic twin pregnancy. We hypothesize that serum concentrations of biomarkers: placental growth factor (PlGF), serum soluble fms-like tyrosine kinase-1 (sFlt-1), and endoglin (Eng) differ between monochorionic and dichorionic twin pregnancies. Methods: A prospective observational study including 43 monochorionic and 36 dichorionic twin gestation was conducted. Blood samples were collected twice from all participants: between 11 + 0 and 13 + 6 and between 32 + 0 and 34 + 0 weeks of gestation. PlGF, sFlt-1 and Eng were measured using immnunoenzymatic assays. Results: We found a significantly higher concentration of sFlt-1 in dichorionic in comparison to monochorionic pregnancies in both the first and third trimesters. PlGF and sEng levels did not differ between mono- and dichorionic gestation in both study periods. sFlt-1 level was related to twin gestation chorionicity, while PlGF expression was not. PlGF, sFlt-1 and sEng concentrations increased significantly during gestation and were much higher in the third trimester compared to the values measured in the first trimester. Conclusions: Angiogenic biomarkers expression differ between dichorionic and monochorionic twin pregnancy. The sFlt-1 level is related to chorionicity of a twin gestation.

Placental characteristics in different types of selective fetal growth restriction in monochorionic diamniotic twins.

This study aimed to explore the differences in placental characteristics among three types of selective fetal growth restriction (sFGR) in monochorionic diamniotic twin pregnancies. A total of 123 placentas with sFGR between April 2013 and October 2019 were retrospectively analyzed after dye injection. Placental characteristics were compared among the three types. The gestational age at diagnosis and delivery was less in sFGR II and III than in sFGR I (22.9 [21.7-33.6], 23.3 [20.0-26.1] and 25.7 [19.0-35.0] weeks, p<0.001; 32.3 [31.6-35.1], 34.1 [29.9-34.7] and 35.5 [34.0-37.0] weeks, p<0.001). The birthweight discordance ratio was less in sFGR I than in sFGR II (0.28 [0.14-0.43] and 0.30 [0.23-0.37], p<0.001). The prevalence of a thick artery-artery anastomosis was higher in sFGR III than in sFGR I or II (81.8%, 44.9% and 48.6%, p=0.010). The placental territory discordance ratio was higher in sFGR II and III than in sFGR I (0.60 [0.17-0.88], 0.60 [0.01-0.80] and 0.50 [0.01-0.71], p=0.001). Compared with sFGR I, the earlier onset time of sFGR II and III might be due to their higher placental territory discordance. The prevalence of thick artery-artery anastomoses was expected to be higher in sFGR III than in sFGR I or II.

Amniotic band syndrome in a monochorionic diamniotic twin pregnancy after rupture of the dividing membrane in the early second trimester: A case report

BackgroundAmniotic band syndrome is a rare phenomenon, but it can result in serious complications. We report herein our experience of amniotic band syndrome in a monochorionic diamniotic twin pregnancy where rupture of the dividing membrane occurred early in the second trimester.Case PresentationA 29-year-old nulliparous woman was referred to us for management of her monochorionic diamniotic twin pregnancy at 10 weeks of gestation. When we were unable to identify a dividing membrane at 15 weeks of gestation using two-dimensional ultrasonography, we used three-dimensional ultrasonography to confirm its absence. Both modalities showed that the left arm of baby B was swollen and attached to a membranous structure originating from the placenta at 18 weeks of gestation. Tangled umbilical cords were noted on magnetic resonance imaging at 18 weeks of gestation. Emergency cesarean delivery was performed at 30 weeks of gestation because of the nonreassuring fetal status of baby A. The left arm of baby B had a constrictive ring with a skin defect. Both neonates had an uncomplicated postnatal course and were discharged around 2 months after delivery.ConclusionsAttention should be paid to the potential for amniotic band syndrome if rupture of the dividing membrane between twins is noted during early gestation.

Fetoscopic visualization of a cervical funneling with sludge

Cervical funneling with sludge is an ultrasonographic marker of preterm birth. In this communication, we demonstrate this finding with direct fetoscopic visualization. A primigravid patient was referred at 17 weeks’ gestation with a monochorionic diamniotic twin pregnancy complicated by stage III twin-to-twin transfusion syndrome and a cervical length of 13 mm with funneling and sludge (Figure 1, A). At 17+3 weeks, a fetoscopic laser photocoagulation was performed, and examination of the funneled cervix (Figure 1, B) demonstrated accumulations of an amorphous material corresponding to the sludge (Figure 1, C) (Video).

Amniotic fluid microRNA profiles in twin-twin transfusion syndrome with and without severe recipient cardiomyopathy

Twin-twin transfusion syndrome presents many challenges for clinicians, and the optimal means of identifying pregnancies that will benefit most from intervention is controversial. There is currently no clinically available biomarker to detect twin-twin transfusion syndrome or to stratify cases based on the risk factors. microRNAs are small RNAs that regulate gene expression and are biomarkers for various disease processes, including adult and pediatric heart failure. To date, no studies have investigated amniotic fluid microRNAs as biomarkers for disease severity, specifically for severe recipient cardiomyopathy in twin-twin transfusion syndrome cases. This study aimed to assess whether amniotic fluid microRNAs could be useful as biomarkers to identify pregnancies at greatest risk for severe recipient cardiomyopathy associated with twin-twin transfusion syndrome. Amniotic fluid was collected at the time of amnioreduction or selective fetoscopic laser photocoagulation from monochorionic diamniotic twin pregnancies with twin-twin transfusion syndrome at any stage. Fetal echocardiography was performed on all twins before the procedure, and severe cardiomyopathy was defined as a right ventricular myocardial performance index of the recipient fetus of >4 Z-scores. microRNA was extracted from the amniotic fluid samples and analyzed using an array panel assessing 379 microRNAs (TaqMan Open Array, ThermoFisher). Student t tests were performed to determine significant differences in microRNA expression between pregnancies with severe recipient cardiomyopathy and those with preserved cardiac function. A stringent q value of <.0025 was used to determine differential microRNA expression. Random forest plots identified the top 3 microRNAs that separated the 2 groups, and hierarchical cluster analysis was used to determine if these microRNAs properly segregated the samples according to their clinical groups. A total of 14 amniotic fluid samples from pregnancies with twin-twin transfusion syndrome with severe cardiomyopathy were compared with samples from 12 twin-twin transfusion syndrome control cases with preserved cardiac function. A total of 110 microRNAs were identified in the amniotic fluid samples. Twenty microRNAs were differentially expressed, and the top 3 differentiating microRNAs were hsa-miR-200c-3p, hsa-miR-17-5p, and hsa-miR-539-5p. Hierarchical cluster analysis based on these top 3 microRNAs showed a strong ability to differentiate severe cardiomyopathy cases from controls. The top 3 microRNAs were used to investigate the sensitivity and specificity of these microRNAs to differentiate between the 2 groups with a receiver operating characteristic curve demonstrating sensitivity and specificity of 80.8%. All 20 differentially expressed microRNAs were down-regulated in the group with severe cardiomyopathy. Amniotic fluid microRNAs demonstrated differential expression between twin-twin transfusion syndrome recipient fetuses with severe cardiomyopathy and those without and have the potential to be important biomarkers of disease severity in this population.

An incidental rare finding of a TRAP sequence during a caesarean section: A case report

Twin reversed arterial perfusion (TRAP) sequence is an anomaly of monochorionic twin pregnancies where one twin has an absent, non-functioning or rudimentary heart while the other twin may be normal. The condition occurs because of early development of arterio -arterial anastomoses between the umbilical arteries of twin foetuses that share a fused placenta. In this condition, the affected anomalous (acardiac twin) is perfused by the normal twin (pump twin) via an arterio-arterial anastomosis. The affected twin (acardiac twin) presents with malformations such as absent (acradia) or rudimentary heart, underdeveloped or missing head, upper body and limbs. As pump twin has to provide circulation to itself as well as the perfused twin, this increased burden to perfuse acardiac twin increases the risk of developing cardiac failure in pump twin. Here we present such a case of 22-year-old, which was diagnosed per operatively during caesarean section at department of obstetrics &amp; gynecology, Rukshamaniben General Hospital, Ahmedabad.

Role of Imaging in Obstetric Interventions: Criteria, Considerations, and Complications.

US has an established role in the prenatal detection of congenital and developmental disorders. Many pregnant women undergo US at 18-20 weeks of gestation for assessment of fetal anatomy and detection of structural anomalies. With advances in fetoscopy and minimally invasive procedures, in utero fetal interventions can be offered to address some of the detected structural and physiologic fetal abnormalities. Most interventions are reserved for conditions that, if left untreated, often cause in utero death or a substantially compromised neonatal outcome. US is crucial for preprocedural evaluation and planning, real-time procedural guidance, and monitoring and assessment of postprocedural complications. Percutaneous needle-based interventions include in utero transfusion, thoracentesis and placement of a thoracoamniotic shunt, vesicocentesis and placement of a vesicoamniotic shunt, and aortic valvuloplasty. Fetoscopic interventions include myelomeningocele repair and tracheal balloon occlusion for congenital diaphragmatic hernia. In rare cases, open hysterotomy may be required for repair of a myelomeningocele or resection of a sacrococcygeal teratoma. Monochorionic twin pregnancies involve specific complications such as twin-twin transfusion syndrome, which is treated with fetoscopic laser ablation of vascular connections, and twin reversed arterial perfusion sequence, which is treated with radiofrequency ablation. Finally, when extended placental support is necessary at delivery for repair of congenital high airway obstruction or resection of lung masses, ex utero intrapartum treatment can be planned. Radiologists should be aware of the congenital anomalies that are amenable to in utero interventions and, when necessary, consider referral to centers where such treatments are offered. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ©RSNA, 2021.

Perinatal and Long Term Outcome of Monochorionic Twins Complicated by Twin-Twin Transfusion Syndrome

Twin-twin transfusion syndrome (TTTS) is the most harmful complication of monochorionic twin pregnancies. Fetoscopic laser coagulation of placental vascular anastomoses represents the causative and first-line treatment for the disease. Substantial improvements in survival rates and long-term outcome have been achieved during the last 20 years of practice. This is due to improvements in antenatal detection of the condition, surgical skills and centralization in the referral fetal therapy unit, as well as postnatal intensive care and follow up programs. Major morbidity issues concern cardiologic, renal and cerebral functions and are mainly caused by intrauterine haemodynamic imbalances and prematurity. This review summarizes the current evidence on the prognosis of monochorionic twins survivors after TTTS treated by laser surgery, focusing on perinatal and long-term outcomes.

Why does second trimester demise of a monochorionic twin not result in acardiac twinning?

BackgroundWe previously explained why acardiac twinning occurs in the first trimester. We raised the question why a sudden demised monochorionic twin beyond the first trimester does not lead to acardiac twinning. We argued that exsanguinated blood from the live twin would strongly increase the demised twins' vascular resistance, preventing its perfusion and acardiac onset. However, our current hypothesis is that perfusion of the demised twin does occur but that it is insufficient for onset of acardiac twinning.MethodsWe analyzed blood pressures and flows in a vascular resistance model of a monochorionic twin pregnancy where one of the fetuses demised. The resistance model consists of a demised twin with a (former) placenta, a live twin and its placenta, and arterioarterial (AA) and venovenous placental anastomoses. We assumed that only twins with a weight of at least 33% of normal survived the first trimester and that exsanguination of more than 50% of its blood volume is fatal for the live twin.ResultsAt 20 weeks, only AA anastomoses with radii ≲1 mm keep the exsanguinated blood volume below 50%. Then, perfusion of the deceased body with arterial blood from the live fetus is about 5–40 times smaller than when that body was alive. Beyond 20 weeks, this factor is even smaller. At 14 weeks, this factor is at most 2.ConclusionWe hypothesize that this small perfusion flow of arterial blood prevents further growth of the deceased body and hence precludes onset of acardiac twinning.

Selective intrauterine growth restriction of monochorionic diamniotic twin pregnancies: what is the neonatal prognosis?

selective intrauterine growth restriction of monochorionic diamniotic twin pregnancies: what is the neonatal prognosis?

Selective intrauterine growth restriction of monochorionic diamniotic twin pregnancies: what is the neonatal prognosis?

selective intrauterine growth restriction of monochorionic diamniotic twin pregnancies: what is the neonatal prognosis?

Perinatal Outcomes following Radiofrequency Ablation in Complicated Monochorionic Multiple Pregnancies

Background Radiofrequency ablation (RFA) is considered as an optional treatment method in complicated monochorionic (MC) twin pregnancies. The purpose of this study is to investigate the main factors of fetal death after such treatment procedure. The study also compares the perinatal outcomes among various groups of indication and gestational age (GA) at procedure. Materials and Methods: This prospective cohort study considers 195 cases of MC multiple pregnancies including one twin with twin-twin transfusion syndrome, selective intrauterine growth restriction ,sever anomaly and twin reversed arterial perfusion sequence(TRAP) which underwent selected reduction using RFA from 2016 to 2018 at Yas Hospital, Tehran, Iran. The GA at RFA categorized as 16- 19+6 wks., 20-23+6 wks., and 24-28 wks. The analysis of risk factors of fetal death after RFA is based on multivariable logistic regression model. Results: The result of analysis reveals that the rate of co-twin anemia after RFA in anomaly indication was higher than the other indications significantly (p=0.038) while according to GA categories, it is significantly lower in 20-23+6 weeks. (p=0.016). Three independent significant factors contributing in fetal death after RFA were co-twin anemia after RFA, TRAP and anomaly indications of RFA and GA at RFA, respectively. Conclusion The co-twin anemia after RFA was found the most contributing factor of fetal death. As the results showed that the rate of co-twin anemia after RFA is significantly low in 20-23+6 weeks of GA, such GA is suggested for RFA procedure to reduce the fetal death.

Perinatal outcome of monochorionic diamniotic twin pregnancy complicated by selective intrauterine growth restriction according to umbilical artery Doppler flow pattern: single-center study using strict fetal surveillance protocol.

To determine the perinatal outcome of monochorionic diamniotic (MCDA) twin pregnancies complicated by selective intrauterine growth restriction (sIUGR), which were classified according to the umbilical artery (UA) Doppler flow pattern of the IUGR twin. This was a retrospective cohort study of all MCDA twin pregnancies diagnosed with sIUGR and managed at a single tertiary referral center between 2012 and 2018. Cases were classified according to the UA Doppler flow pattern of the IUGR twin as Type I (positive end-diastolic flow), Type II (persistently absent/reversed end-diastolic flow) or Type III (intermittently absent/reversed end-diastolic flow). Patients with Type-II or -III sIUGR were hospitalized at 26-28 weeks of gestation for increased fetal surveillance. Perinatal and immediate and long-term neurodevelopmental outcomes were stratified according to the UA Doppler flow pattern at the final examination. Intact survival rate was defined as the number of infants surviving without neurological impairment, divided by the total number of fetuses. Composite adverse outcome, defined as any mortality, presence of severe brain lesions on postnatal transcranial ultrasound or severe neurological morbidity, was also assessed. Of 88 MCDA twin pregnancies with sIUGR included in the study, 28 underwent selective termination by cord occlusion using radiofrequency ablation, resulting in a perinatal survival rate of 89.3% and a median gestational age (GA) at delivery of 33.8 (interquartile range (IQR), 28.8-38.2) weeks for the large cotwin. Expectant management was employed in 60 cases. In 26 (43.3%) cases in the expectant-management group, the classification according to the UA Doppler flow pattern changed during gestation, resulting in 26 (43.3%) cases of Type-I, 22 (36.7%) cases of Type-II and 12 (20.0%) cases of Type-III sIUGR at the final examination. The perinatal survival rate of both twins with sIUGR Types I, II and III at the final examination was 100%, 81.8% and 75.0%, respectively (P = 0.04). Two cases of double fetal death and one case of single fetal death occurred 1-4 weeks after the Doppler pattern had changed from Type I or Type II to Type III. The median GA at delivery was 34.8 (IQR, 33.1-35.7) weeks in Type I, 30.3 (IQR, 28.6-32.1) weeks in Type II and 32.0 (IQR, 31.3-32.6) weeks in Type III (P < 0.01). The total intact survival rate was 100% for Type I, 77.3% for Type II and 75.0% for Type III (P < 0.001). Multivariate analysis demonstrated that early GA at diagnosis (odds ratio (OR), 0.83 (95% CI, 0.69-0.99); P = 0.04) and the presence of Type II or III vs Type I at the last examination (OR, 13.16 (95% CI, 1.53-113.32); P = 0.02) were associated with preterm birth < 32 weeks' gestation. Early GA at diagnosis was also associated with the composite adverse outcome (OR, 0.60 (95% CI, 0.36-0.99); P = 0.04). The classification system of MCDA pregnancy complicated by sIUGR, according to the UA Doppler flow pattern of the IUGR twin at final examination, is associated with perinatal outcome. Importantly, the UA Doppler flow pattern can change during gestation, which has an impact on the risk of fetal death. Nevertheless, under strict fetal surveillance, the perinatal outcome of these pregnancies is favorable. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Prevalence of umbilical artery Doppler waveform abnormality during the early second trimester and the subsequent variation of waveforms in monochorionic diamniotic twin pregnancies: A prospective cohort study

To investigate the prevalence of qualitative abnormal umbilical artery Doppler waveforms (Abnormal UA) during the early second trimester and the subsequent variation of waveforms in monochorionic diamniotic (MCDA) twin pregnancies. This prospective cohort study included 153 MCDA twin pregnancies. Pulsed Doppler examinations for UA were performed at four points, including the free-loop (FL) and near the placental cord insertion site (CI) of each UA, between 16 and 17 weeks' gestation. Cases were classified into positive diastolic waveforms (Type I), persistent Abnormal UA (Type II), and intermittent Abnormal UA (Type III). When the diastolic velocity in UA Doppler was positive twice after different sequential recordings, the cases were determined to have achieved normalization. Follow-up Doppler examinations of the UA were performed at 24, 28, and 32 weeks' gestation. Of all 153 cases, 38 (25%; 19 Type II and 19 Type III cases) showed Abnormal UA at the first examination. Abnormal UA was detectable at FL in all selective intrauterine growth restriction (sIUGR) cases, whereas it was noted only at CI site in some non-sIUGR cases. Abnormal UA normalized in 12 (63%) Type II and 15 (79%) Type III cases. A quarter of MCDA twin pregnancies in the early second trimester demonstrated Abnormal UA. In MCDA twins with Abnormal UA between 16 and 17 weeks' gestation, it is preferable to follow them up to consider the possibility of normalization of Abnormal UA as well as features of UA waveforms specific to FL and CI.