BACKGROUND: Perforation of the intertwin membrane can occur as a complication of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS). Data on the occurrence and the risk of subsequent cord entanglement are limited. The objective of this study was to assess the prevalence, risk factors and outcome of intertwin membrane perforation, and cord entanglement after laser surgery for TTTS.
METHODS: In this multicenter retrospective study, we included all TTTS pregnancies treated with laser surgery in two fetal therapy centers, Shanghai (China) and Leiden (the Netherlands) between 2002 and 2020. We evaluated the occurrence of intertwin membrane perforation and cord entanglement after laser, based on routine fortnightly ultrasound examination and investigated the risk factors and the association with adverse short- and long-term outcomes.
RESULTS: Perforation of the intertwin membrane occurred in 118 (16%) of the 761 TTTS pregnancies treated with laser surgery and was followed by cord entanglement in 21% (25/118). Perforation of the intertwin membrane was associated with higher laser power settings, 45.8 Watt versus 42.2 Watt (p = 0.029) and a second fetal surgery procedure 17% versus 6% (p < 0.001). The group with intertwin membrane perforation had a higher rate of caesarean section (77% vs. 31%, p < 0.001) and a lower gestational age at birth (30.7 vs. 33.3 weeks of gestation, p < 0.001) compared to the group with an intact intertwin membrane. Severe cerebral injury occurred more often in the group with intertwin membrane perforation, 9% (17/185) versus 5% (42/930), respectively (p = 0.019). Neurodevelopmental outcome at 2 years of age was similar between the groups with and without perforation of the intertwin membrane and between the subgroups with and without cord entanglement.
CONCLUSIONS: Perforation of the intertwin membrane after laser occurred in 16% of TTTS cases treated with laser and led to cord entanglement in at least 1 in 5 cases. Intertwin membrane perforation was associated with a lower gestational age at birth and a higher rate of severe cerebral injury in surviving neonates.

Selective fetoscopic laser photocoagulation (SFLP) for twin-to-twin transfusion syndrome (TTTS) is challenging for new surgeons at the start of their learning curve. We described an approach utilising telementoring and team-based training to facilitate rapid attainment of the skills required for safe and efficient practice with a limited caseload.
We conducted a prospective observational study of SFLP performed by the novice primary surgical team in three stages: under direct on-site supervision from an expert mentor (Group 1), with remote tele-guidance from that mentor (Group 2) and independently (Group 3), at an academic tertiary hospital in Singapore. The primary team undertook regular training on high-fidelity tissue models to accelerate skills acquisition and complement the surgical performance.
9 patients diagnosed with Stage 2 TTTS were assessed for procedural characteristics, surgical outcomes and perinatal survival following SFLP. There were no significant differences in operative duration, anastomoses ablated, gestational age or birth weight at delivery. The complications observed were: recurrent TTTS (22.2% of pregnancies), twin anaemia polycythaemia sequence (33.3%), preterm prelabour membrane rupture (22.2%) and delivery at < 32 weeks (44.4%). ≥ 1 twin was live-born in 88.9% of cases, while postnatal survival to six months of ≥ 1 twin occurred in 77.8% of cases.
Systematic mentoring and specialised skills training are useful in aiding new surgeons to negotiate the steep learning curve and achieve good outcomes at the start of a new practice, particularly in the setting of low patient numbers. This is best paired with dedicated model training to achieve and maintain surgical dexterity for this complex procedure.

Objectives: To investigate metabolomic perturbations caused by twin-twin transfusion syndrome, metabolic changes associated with fetoscopic laser coagulation in both placental tissue and cord plasma, and to investigate differential metabolites pertinent to varying fetal outcomes, including hemodynamic status, birth weight, and cardiac function, of live-born babies. Methods: Placental tissue and cord plasma samples from normal term or uncomplicated preterm-born monochorionic twins and those complicated by twin-twin transfusion syndrome treated with or without fetoscopic laser coagulation were analyzed by high-performance liquid chromatography metabolomic profiling. Sixteen comparisons of different co-twin groups were performed. Partial least squares-discriminant analysis, metabolic pathway analysis, biomarker analysis, and Spearman\'s correlation analysis were conducted based on differential metabolites used to determine potential biomarkers in different comparisons and metabolites that are pertinent to neonatal birth weight and left ventricular ejection fraction. Results: These metabolomic investigations showed that the cord plasma metabolome has a better performance in discriminating fetuses among different hemodynamic groups than placental tissue. The metabolic alteration of twin-twin transfusion syndrome in these two types of samples centers on fatty acid and lipid metabolism. The fetoscopic laser coagulation procedure improves the metabolomic change brought by this syndrome, making the metabolomes of the treated group less distinguishable from those of the control and preterm birth groups. Certain compounds, especially lipids and lipid-like molecules, are noted to be potential biomarkers of this morbid disease and pertinent to neonatal birth weight and ejection fraction. Conclusions: Fetoscopic laser coagulation can ameliorate the metabolomic alteration caused by twin-twin transfusion syndrome in placental tissue and cord plasma, which are involved mainly in fatty acid and lipid-like molecule metabolism. Certain lipids and lipid-like molecules are helpful in differentiating co-twins of different hemodynamic statuses and are significantly correlated with neonatal birth weight or ejection fraction.

OBJECTIVE: This study aimed to identify selective fetal growth restriction (sFGR) in monochorionic twin (MCT) pregnancy with expectant management.
METHODS: We retrospectively analyzed cases of sFGR between January 2015 and December 2019 in Peking University Third Hospital. We included sFGR according to the International Society of Ultrasound in Obstetrics and Gynecology diagnostic criteria. We excluded those cases where a significant fetal structural abnormality, twin reversed arterial perfusion (TRAP), genetic syndrome or aneuploidy; cases terminated for maternal complications or for personal reasons; pregnancies that had a fetal intervention, such as fetoscopic laser photocoagulation (FLP) for vascular anastomoses, fetal reduction by radiofrequency ablation (RFA) and microwave ablation (MVA). We didn\'t excluded those cases that had amnioreduction therapy. According to the gestational age at onset (before 24 weeks or after), data were analyzed to identify the risk factors associated with fetal prognostic outcomes. Primary outcomes included survival of at least one twin and both twins. Secondary outcomes included gestational age of delivery, live birth weight, Apgar <7 in 5 min, admission to the neonatal unit and neonatal death. Kruskal-Wallis rank tests were used to compare non-normally distributed data, whereas categorical data were matched using Fisher\'s exact test or χ2 tests. ANOVA was used to compare normally distributed data, followed by a post-hoc Bonferroni analysis. Multivariate binary logistic regression was used to identify the factors connected with intrauterine death.
RESULTS: There were 119 pregnancies that qualified for investigation, 75 (63.0%) were categorized as early-onset sFGR and 44 (37.0%) as late-onset sFGR. The rate of survival of at least one twin (82.7% vs. 95.5%), survival of both twins (73.3% vs. 88.6%) were all reduced in the early-onset sFGR group, compared to the late-onset sFGR group. Babies born alive of fetal growth restriction (FGR) and appropriate growth for gestational age (AGA) fetuses showed similar results in the two groups regarding birth weight, 5-min Apgar score <7, neonatal death, and 28-day survival rate. A multivariable model was used to predict the intrauterine death of at least one twin. The odds ratio were significantly higher for superimposed twin-twin transfusion syndrome (TTTS) (OR 17.915, 95%CI 3.699∼86.756) and Types Ⅱ/Ⅲ sFGR (OR 4.619, 95%CI 1.074∼19.869).
CONCLUSIONS: In MCT pregnancies, early-onset sFGR had a poorer survival of at least one or both twins, but there was no statistical difference in the prognosis after live birth, neither for FGR babies nor those of AGA. Superimposed TTTS and Types Ⅱ/Ⅲ sFGR had a worse perinatal outcome. This information could be provided to the parents during prenatal counselling.

Twin-to-twin transfusion syndrome (TTTS) could be treated with fetoscopic laser photocoagulation. For patients with placenta located on the anterior wall of uterus, surgical procedures are difficult. To solve this problem, a flexible fetoscope was designed in our department.
The flexible fetoscope was made up of polyurethane, fiberglass and stainless steel coils. The specular body was soft and could bend encountering obstacles, which reduced the possibility of injury to the fetus and placenta. The distal tip of the body could curve from -180° to +270° with the control of the handweel. Three pregnant women of TTTS with anterior placenta was operated with this instrument.
All pregnant women were treated smoothly and gave live twins birth at term. Through angiography, it was demonstrated that the vascular connections on the surface had been coagulated.
The flexible fetoscope was a novel instrument in treating TTTS, especially for the anterior placenta.

BACKGROUND: Twin-twin transfusion syndrome (TTTS) is a complication in monochorionic twin pregnancies which is preferably treated with fetoscopic laser surgery. A few small studies suggested a possible association between the Solomon laser technique and placental abruption.
METHODS: The objective of this study is to compare the rate of and to explore potential risk factors for placental abruption in TTTS treated with fetoscopic laser surgery according to the Selective and Solomon laser technique. We conducted a large retrospective cohort study of consecutive TTTS-cases treated with fetoscopic laser surgery in Shanghai, China, and Leiden, The Netherlands treated with either the Selective laser technique (Selective group) or Solomon laser technique (Solomon group).
RESULTS: The rate of placental abruption in the Selective group versus the Solomon group was 1.7% (5/289) and 3.4% (15/441), respectively (p = 0.184). No risk factors for placental abruption were identified. Placental abruption was associated with lower gestational age at birth (p = 0.003) and severe cerebral injury (p = 0.003).
CONCLUSIONS: The prevalence of placental abruption in TTTS after fetoscopic laser surgery is low, although it appears higher than in the overall population. Placental abruption is associated with a lower gestational age at birth, which is associated with severe cerebral injury. The rate of placental abruption was not significantly increased with the use of the Solomon technique. Continued research of placental abruption in TTTS is necessary to determine why the rate is higher than in the overall population.

OBJECTIVE: To analyze the discordances of the umbilical artery velocities between pregnancies with twin-twin transfusion syndrome (TTTS) at stage I and those with normal monochorionic-diamniotic (MCDA) twins, and investigate the value of their discordances in predicting TTTS at stage I.
METHODS: We recruited 58 twin pregnancies with TTTS at stage I and 60 normal MCDA twin pregnancies in a tertiary referral center retrospectively. The umbilical artery velocities and their discordances were compared between the normal and TTTS twins.
RESULTS: The discordances of umbilical artery mean diastolic velocity (UA-MDV), umbilical artery time-averaged maximum velocity (UA-TAmax), umbilical artery peak systolic velocity (UA-PSV), and umbilical artery end-diastolic velocity (UA-EDV) were higher in the TTTS group than in the normal group. In TTTS co-twins, the UA-MDV, UA-TAmax, UA-PSV, and UA-EDV in recipients were higher than those in donors. The discordances of UA-TAmax and UA-PSV were found to be independent predicting factors for TTTS at stage I.
CONCLUSIONS: Co-twin umbilical artery velocity discordances were significantly associated with stage I TTTS. The results suggest that UA-TAmax and UA-PSV might be new parameters for predicting TTTS at stage I.

BACKGROUND: Transient donor hydrops (TDH) is defined as donor hydrops developed within days after laser therapy for twin-twin transfusion syndrome (TTTS) followed by resolution later. The purpose of this study was to evaluate the incidence, neonatal outcomes and predisposing factors of post laser therapy TDH in severe TTTS.
METHODS: A total of 142 patients with severe TTTS who received laser therapy were included into this study. The pre-operative characteristics and neonatal outcomes were compared between TTTS with and without post laser therapy TDH. All live neonates received cranial ultrasound examination after delivery, mild cerebral injury was defined as exhibiting at least one of the following: intraventricular hemorrhage (IVH) grade I and II, lenticulostriate vasculopathy and subependymal pseudocysts; severe cerebral injury comprised at least one among the following: IVH grade III or grade IV, cystic periventriculoleukomalacia (PVL) grade II or more, porencephalic cysts, and ventricular dilatation. Fetal survival was defined as living more than 30 days after delivery.
RESULTS:

BACKGROUND: The clinical significance of veno-venous (VV) anastomoses in monochorionic (MC) placentas remains inconclusive and controversial. The purpose of this study was to investigate the correlation between the presence of VV anastomoses and clinical outcome in a large cohort of MC twin pregnancies.
METHODS: All MC placentas injected with colored dye from 2002 to 2014 were included in the study. We excluded MC pregnancies managed with fetoscopic laser surgery.
CONCLUSIONS: A total of 384 MC placentas were analyzed. VV anastomoses were detected in 27% (104/384) of MC placentas. The prevalence of twin-twin transfusion syndrome (TTTS) in MC placentas with VV anastomoses was significantly higher compared to MC placentas without VV anastomoses, 20% (21/104) versus 10% (29/280), respectively (P = .01). The overall perinatal mortality in MC twins with and without VV anastomoses was 16% versus 10%, respectively (P = .02). Risk factor analysis showed the presence of VV anastomoses was associated with perinatal mortality (P = .02; odds ratio (OR): 1.76; 95% confidence interval (CI): 1.11-2.79), but was not an independent risk factor for perinatal mortality (P = .26, OR: .66; 95% CI: .33-1.35) in MC twin pregnancies. However, VV anastomoses was associated with and was an independent risk factor for TTTS (P = .00, OR: 3.59; 95% CI: 1.72-7.47). VV anastomoses-related perinatal mortality may be due to the high rate of TTTS in MC twins with VV anastomoses.
CONCLUSIONS: The presence of VV anastomoses is correlated with TTTS and perinatal mortality, but is not an independent risk factor for perinatal mortality in MC twin pregnancies.