Fetoscopic Laser Surgery Research Articles

A prospective pilot study of fetoscopic laser surgery for twin-to-twin transfusion syndrome between 26 and 27 weeks of gestation

ObjectiveThe aim of this study is to clarify the feasibility and efficacy of fetoscopic laser photocoagulation of placental vascular communicating vessels (FLP) on twin–twin transfusion syndrome (TTTS) after 26 weeks of gestation. Materials and MethodsThis is a prospective pilot study investigating all cases of TTTS between 26 weeks and 27 weeks during 2012 and 2013 in Japan. The primary endpoints in this study were the feasibility of FLP and rate of harmful complications for the mother's health. Also, perinatal prognosis was investigated. ResultsSix cases were enrolled and underwent FLP. Two of the six cases were classified preoperatively as Quintero Stage II and four cases were Stage III. FLP was completely achieved in all six cases. No severe maternal complications were noted during and immediately after the surgery. All but one case continued the pregnancies > 14 days after FLP. The median gestational age at delivery was 33.4 weeks (28.0–36.6 weeks). All 12 fetuses survived at the 28th day in the neonatal period. No case was diagnosed with cerebral lesion at the neonatal period. ConclusionThis prospective pilot study shows that FLP could be a therapeutic option for TTTS between 26 weeks and 27 weeks of gestation.

Comparison Between Monochorionic and Dichorionic Placentas With Special Attention to Vascular Anastomoses and Placental Share.

Placental vascular anastomoses in twins lead to a shared circulation and may subsequently enable the development of severe complications such as twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). The presence of vascular anastomoses has frequently and systematically been studied in monochorionic (MC) placentas, but only rarely in dichorionic (DC) placentas. The aim of this study was to compare the prevalence of vascular anastomoses and evaluate the sharing discordance in MC and DC placentas. All consecutive placentas of MC and DC twins delivered at the Leiden University Medical Center (the Netherlands) and Medical University of Warsaw (Poland) from 2012 to 2015 were routinely injected with colored dye and included in the study. We excluded twin pregnancies treated with fetoscopic laser surgery. A total of 258 placentas were analyzed in this study, including 134 MC placentas and 124 DC placentas. Vascular anastomoses were present in 99% (133/134) of MC placentas and 0% of DC placentas (p < .01). Placental share discordance between MC twins was significantly larger compared to DC twins, 19.8 (interquartile range [IQR] 8.1-33.3) and 10.8 (IQR 6.2-19.0), respectively (p < .01). Vascular anastomoses associated complications occurred in 16% (22/134) MC twins. Our findings show that vascular anastomoses are almost ubiquitous in MC placentas, but non-existent in DC placentas. In addition, unequal placental sharing appears to be more common in MC than in DC placentas.

Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.

Monochorionic twins share a single placenta and are connected with each other through vascular anastomoses. Unbalanced inter-twin blood transfusion may lead to various complications, including twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). TAPS was first described less than a decade ago, and the pathogenesis of TAPS results from slow blood transfusion from donor to recipient through a few minuscule vascular anastomoses. This gradually leads to anemia in the donor and polycythemia in the recipient, in the absence of twin oligo-polyhydramnios sequence (TOPS). TAPS may occur spontaneously in 3-5% of monochorionic twins or after laser surgery for TTTS. The prevalence of post-laser TAPS varies from 2% to 16% of TTTS cases, depending on the rate of residual anastomoses. Pre-natal diagnosis of TAPS is currently based on discordant measurements of the middle cerebral artery peak systolic velocity (MCA-PSV; >1.5 multiples of the median [MoM] in donors and 8 g/dL), and at least one of the following: reticulocyte count ratio >1.7 or minuscule placental anastomoses. Management includes expectant management, and intra-uterine blood transfusion (IUT) with or without partial exchange transfusion (PET) or fetoscopic laser surgery. Post-laser TAPS can be prevented by using the Solomon laser surgery technique. Short-term neonatal outcome ranges from isolated inter-twin Hb differences to severe neonatal morbidity and neonatal death. Long-term neonatal outcome in post-laser TAPS is comparable with long-term outcome after treated TTTS. This review summarizes the current knowledge after 10 years of research on the pathogenesis, diagnosis, management, and outcome in TAPS.

Does anemia-polycythemia complicating twin-twin transfusion syndrome affect outcome after fetoscopic laser surgery?

Twin anemia-polycythemia sequence (TAPS) can occur as a unique disease or as a complication of twin-twin transfusion syndrome (TTTS). Middle cerebral artery (MCA) Doppler studies are not currently part of the routine evaluation of monochorionic twins since they are not used in the Quintero staging system. As such, the true incidence of TAPS is unknown. We aimed to compare the characteristics and outcomes of twin pregnancies with TTTS complicated by spontaneous anemia-polycythemia vs those with TTTS alone. This was a secondary analysis of data collected prospectively from a cohort of 156 consecutive patients undergoing fetoscopic laser surgery for TTTS, between October 2011 and August 2014. TAPS was defined as discordance in the preoperative MCA peak systolic velocity (PSV), with one twin fetus having MCA-PSV ≤ 1.0 multiples of the median (MoM) and the other having MCA-PSV ≥ 1.5 MoM. Maternal demographics as well as preoperative, operative and postoperative variables were analyzed. Included in the final analysis were 133 patients with complete records: 11 cases with TTTS with anemia-polycythemia and 122 cases with TTTS alone. There was no difference in maternal body mass index, gestational age (GA) at procedure, rate of preterm prelabor rupture of membranes or GA at delivery between the two groups. Patients with TTTS and anemia-polycythemia were more likely to be older (P = 0.03) and parous (P = 0.04) and had a significantly lower number of placental anastomoses (P = 0.01). The dual live-birth rate was similar for both groups (P = 0.76). Cases of TTTS with anemia-polycythemia were more likely to be found in parous and older women and were characterized by fewer vascular anastomoses. TTTS with anemia-polycythemia was not associated with worse perinatal outcome after laser therapy. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Operator competence in fetoscopic laser surgery for twin-twin transfusion syndrome: validation of a procedure-specific evaluation tool.

Fetoscopic laser surgery for twin-twin transfusion syndrome is a procedure for which no objective tools exist to assess technical skills. To ensure that future fetal surgeons reach competence prior to performing the procedure unsupervised, we developed a performance assessment tool. The aim of this study was to validate this assessment tool for reliability and construct validity. We made use of a procedure-specific evaluation instrument containing all essential steps of the fetoscopic laser procedure, which was previously created using Delphi methodology. Eleven experts and 13 novices from three fetal medicine centers performed the procedure on the same simulator. Two independent observers assessed each surgery using the instrument (maximum score: 52). Interobserver reliability was assessed using Spearman correlation. We compared the performance of novices and experts to assess construct validity. The interobserver reliability was high (Rs = 0.974, P < 0.001). Checklist scores for experts and novices were significantly different; the median score for novices was 28/52 (54%), whereas that for experts was 47.5/52 (91%) (P < 0.001). The procedure time and fetoscopy time were significantly shorter (P < 0.001) for experts. Residual anastomoses were found in 1/11 (9%) procedures performed by experts and in 9/13 (69%) procedures performed by novices (P = 0.005). Multivariable analysis showed that the checklist score, independent of age and gender, predicted competence. The procedure-specific assessment tool for fetoscopic laser surgery shows good interobserver reliability and discriminates experts from novices. This instrument may therefore be a useful tool in the training curriculum for fetal surgeons. Further intervention studies with reassessment before and after training may increase the construct validity of the tool. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

60: Preterm Delivery (PTD) after fetoscopic laser surgery (FLS) for twin twin transfusion syndrome (TTTS): etiology and risk factors

60: Preterm Delivery (PTD) after fetoscopic laser surgery (FLS) for twin twin transfusion syndrome (TTTS): etiology and risk factors

413: Neonatal outcomes in monochorionic diamniotic (MCDA) twin pregnancies: uncomplicated vs. twin to twin transfusion syndrome survivors (TTTS) after fetoscopic laser surgery (FLS)

413: Neonatal outcomes in monochorionic diamniotic (MCDA) twin pregnancies: uncomplicated vs. twin to twin transfusion syndrome survivors (TTTS) after fetoscopic laser surgery (FLS)

Complex Fetal Care: Twin Anemia Polycythemia Sequence

Twin anemia polycythemia sequence is a rare condition in monochorionic twin pregnancies that has only recently been described. It can occur spontaneously or as a result of fetoscopic laser surgery for twin to twin transfusion syndrome. The size of the placental connections and the flow of blood between tiny anastomoses allow for chronic changes in the hemodynamic states of each fetus. The chronic nature of the pathophysiology leads to reticulocytosis in the donor twin and limits the fluid-level discrepancies between amniotic sacs, which differentiates it from twin to twin transfusion syndrome, which is thought to be an acute process. Several in utero procedures have been described to treat this condition; however, because of the rarity of the condition, data are limited. Postnatal treatment includes packed red blood cell transfusion for the donor twin and partial exchange transfusion for the recipient twin, along with standard medical neonatal care. Long-term outcomes data are limited; however, one study revealed normal neurodevelopment in a small cohort of patients.

Simulator training in fetoscopic laser surgery for twin-twin transfusion syndrome: a pilot randomized controlled trial

To evaluate the effect of a newly developed training curriculum on the performance of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS) using an advanced high-fidelity simulator model. Ten novices were randomized to receive verbal instructions and either skills training using the simulator (study group; n = 5) or no training (control group; n = 5). Both groups were evaluated with a pre-training and post-training test on the simulator. Performance was assessed by two independent observers and comprised a 52-item checklist for surgical performance (SP) score, measurement of procedure time and number of anastomoses missed. Eleven experts set the benchmark level of performance. Face validity and educational value of the simulator were assessed using a questionnaire. Both groups showed an improvement in SP score at the post-training test compared with the pre-training test. The simulator-trained group significantly outperformed the control group, with a median SP score of 28 (54%) in the pre-test and 46 (88%) in the post-test vs 25 (48%) and 36 (69%), respectively (P = 0.008). Procedure time decreased by 11 min (from 44 to 33 min) in the study group vs 1 min (from 39 to 38 min) in the control group (P = 0.69). There was no significant difference in the number of missed anastomoses at the post-training test between the two groups (1 vs 0). Subsequent feedback provided by the participants indicated that training on the simulator was perceived as a useful educational activity. Proficiency-based simulator training improves performance, indicated by SP score, for fetoscopic laser therapy. Despite the small sample size of this study, practice on a simulator is recommended before trainees carry out laser therapy for TTTS in pregnant women.

Perinatal outcome after fetoscopic laser surgery for twin-to-twin transfusion syndrome in triplet pregnancies.

The introduction of fetoscopic laser surgery of placental anastomoses has led to a significant improvement of perinatal outcome of twin pregnancies affected by twin-to-twin-transfusion syndrome (TTTS). To quantify the perinatal outcome and neurological morbidity in triplet pregnancies complicated by TTTS, which were treated with fetoscopic laser surgery. Medline, Embase, Cinahl and Cochrane were searched. The outcomes observed were: fetal and perinatal survival, preterm birth and abnormal neurological outcome. Two authors reviewed all abstracts independently. Meta-analyses of proportions were used to combine data. Eight studies (126 triplet pregnancies, 104 dichorionic-triamniotic [DCTA] and 22 monochorionic-triamniotic [MCTA]) treated with fetoscopic laser surgery were included in this review. In DCTA and MCTA pregnancies, fetal losses were 18.9% and 28.9%, respectively; perinatal losses were 23.6% and 75.0%; preterm births <28 weeks of gestation were 16.9% and 37.1%; preterm births <32 weeks of gestation were 50.0% and 69.5%; at least one fetus survived in 95.4% and 88.9% of the pregnancies; at least two fetuses survived in 81.8% and 68.3% of the pregnancies; and in 55.9% and 48.4% pregnancies all triplets survived. Finally, the incidence of abnormal neurological outcomes ranged from 0 to 37% in DCTA and from 0 to 50% in MCTA triplets. Both DTCA and MCTA triplet pregnancies affected by TTTS are at high risk of adverse perinatal outcome. Both DTCA and MCTA triplet pregnancies affected by TTTS are at high risk of adverse perinatal outcome.

Pulmonary stenosis in complicated monochorionic twin pregnancies: prevalence, management and outcome.

To review prevalence, management and prognostic factors of pulmonary stenosis (PS) in monochorionic diamniotic (MCDA) pregnancies complicated by twin-to-twin transfusion syndrome (TTTS). Retrospective study over the last 10 years in a single referral center. We reviewed fetal echocardiography data of all MC twin cases with diagnosis of isolated PS. We assessed fetoscopy characteristics of those that underwent laser coagulation. We collected data regarding perinatal outcome, neonatal echocardiography and cardiac management. We found 24 cases of isolated PS among 2091 MCDA pregnancies. Among 1052 complicated MCDA that underwent fetal laser surgery, 22 (2.09%) developed PS of which 20 were diagnosed prenatally. Two cases were diagnosed in uncomplicated MCDA pregnancies (0.2%). Four of 22 (18.18%) cases with TTTS showed in utero regression after laser treatment. Thirteen newborns (65%) required valvular dilatation. Peak systolic velocities in the pulmonary artery trunk (PSV-PA) at diagnosis and the interval between the diagnosis of TTTS and that of PS were significantly different (p < 0.001 and p = 0.05 respectively) between PS requiring cardiac intervention and those who did not. An elevated PSV-PA at the time of PS diagnosis and a short time-interval between fetoscopic laser surgery and PS diagnosis are predictive of the need for interventional treatment after birth.

Donor Death After Selective Fetoscopic Laser Surgery for Twin-Twin Transfusion Syndrome.

To assess the incidence, timing, and risk factors for death of the donor fetus after fetoscopic laser surgery, we evaluated our cohort of patients who underwent the procedure for twin-twin transfusion syndrome. This was a prospective cohort study of 166 consecutive patients with twin-twin transfusion syndrome at a single center. Fetal death was diagnosed by ultrasonography after surgery and before onset of labor. Risk factors for death of the donor twin were identified on univariate analysis and then subjected to multivariate, stepwise, logistic regression analysis. Donor demise occurred in 20 (13%) cases and recipient twin death occurred in four (2.6%). The median procedure to death interval was 4 days (range 1-89 days). Risk factors for donor death were fetal growth discordance greater than 30% (odds ratio [OR] 6.7, 95% confidence interval [CI] 2-23), reverse end-diastolic velocity in the donor umbilical artery (OR 25.0, 95% CI 2-290), a marginal and velamentous cord insertion (OR 4.4, 95% CI 1-19), and an increased number of anastomoses (OR 1.2, 95% CI 1.1-1.5). All four donors with both fetal growth discordance greater than 30% and reverse end-diastolic velocity in the donor umbilical artery resulted in a demise. Four risk factors significantly affecting acute and delayed donor demise after fetoscopic laser surgery were identified. The presence of both fetal growth discordance greater than 30% and reverse end-diastolic velocity in the donor umbilical artery was highly predictive of donor demise in our cohort. Knowledge of these risk factors can aid in counseling and assist patients in choosing the most appropriate intervention in the management of twin-twin transfusion syndrome. III.

Veno–venous anastomoses in twin–twin transfusion syndrome: A multicenter study

IntroductionThe aim of this study is to evaluate the prevalence of veno–venous (VV) anastomoses in a large cohort of monochorionic (MC) twin placentas with twin–twin transfusion syndrome (TTTS) compared to a control group of MC placentas without TTTS. MethodsAll TTTS placentas not treated with fetoscopic laser surgery (TTTS group) and examined at five international fetal therapy centers were included in this study and compared with a control group of MC placentas without TTTS (non-TTTS group). MC placentas were routinely injected with colored dye. We recorded the presence of VV and arterio-arterial (AA) anastomoses. ResultsA total of 414 MC placentas were included in this study (TTTS group, n = 106; non-TTTS group, n = 308). The prevalence of VV anastomoses was significantly higher in the TTTS group than in the non-TTTS group, 36% (38/106) and 25% (78/308), respectively (p = .04; odds ratio (OR) 1.65; 95% confidence interval (CI): 1.03–2.64). In the subgroup of MC placentas without AA anastomoses, the prevalence of VV anastomoses in the TTTS group and non-TTTS group was 32% (18/57) and 8% (2/25), respectively (p = .03; OR: 5.31; 95% CI: 1.13–24.98). DiscussionVV anastomoses are detected more frequently in TTTS placentas than in MC placentas without TTTS and may thus play a role in the development of TTTS.

Histologic changes of the fetal membranes after fetoscopic laser surgery for twin-twin transfusion syndrome.

Preterm premature rupture of membranes remains a major complication after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS). We studied the histologic changes of fetal membranes post-FLS and investigated a possible impact of amniotic fluid (AF) dilution. Fetal membranes of 31 pregnancies that underwent FLS for TTTS were investigated histologically at delivery at different sites: trocar site of recipient sac and at distance, donor sac, and inter-twin membrane. The trocar insertion site on the recipient sac showed no signs of histologic hallmarks of healing. Wide-spread alteration in collagen organization and higher apoptotic index in the amnion of the recipient sac which were absent in donor's and reference membranes. To explain the mechanisms, we analyzed the AF composition of recipient sacs from TTTS pregnancies vs. GA-matched healthy singleton controls and found glucose, protein and lactate dehydrogenase activity were all significantly lower in TTTS sacs consistent with over-dilution of recipient's AF (~2-fold). In-vitro exposure of healthy amniochorion to analogous dilutional stress conditions recapitulated the histologic changes and induced apoptosis and autophagy. Alteration in structural integrity of the recipient's amniochorion, possibly in response to dilution stress, along with ineffective repair mechanisms may explain the increased incidence of preterm birth post-FLS.

Placental characteristics of twin-to-twin transfusion syndrome

To explore the prevalence, number and size of anastomoses, placenta sharing and placental cord insertion in twin-to-twin transfusion syndrome (TTTS). A total of 97 monochorionic placentas were collected from June 2013 to June 2014 during fetoscopic laser surgery or selective feticide. After eliminating 23 placentas of selective intrauterine growth restriction (sIUGR), 79 placents were analyzed. There were 24 placentas of TTTS and 32 placentas of normal monochorionic twins (McT) without complex twin preganancy. Placental sharing, placental cord insertion, angioarchitecture and diameter of vascular anastomosis were assessed by placental injection with colored dye and compared between TTTS and McT without complex twin preganancy. (1) Arterio-arterial (AA) anastomoses were detected in 37.5% of TTTS placentas versus 75.0% in normal McT placentas (P<0.01). (2) The median number of AA anastomoses in TTTS group was significantly less than that in normal group (0.0 vs 1.0, P<0.01). And the median total diameter of AA anastomoses in TTTS group was significantly smaller than that in normal group (0.00 vs 2.25 mm, P<0.01). (3) The incidence of placentas with at least one cord non-central insertion (70.8% vs 62.5%, P>0.05), velamentous insertion (25.0% vs 6.3%, P>0.05) in TTTS and normal McT had no difference respectively. The placental territory discordance (PTD) had no difference between TTTS and normal McT (0.33 vs 0.22, P>0.05). AA anastomosis occurs less frequently in TTTS placentas, supporting the concept of a protective role of AA anastomoses in TTTS. McT placentas without AA anastomosis have high risk for TTTS. The compensatory ablitiy of AA anastomosis may determine the time of TTTS onset. Non-central or velamentous cord insertion, placental sharing discordance are not risk factors for TTTS.

Identification of essential steps in laser procedure for twin-twin transfusion syndrome using the Delphi methodology: SILICONE study.

To determine, by expert consensus, the essential substeps of fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) that could be used to create an authority-based curriculum for training in this procedure among fetal medicine specialists. A Delphi survey was conducted among an international panel of experts (n = 98) in FLS. Experts rated the substeps of FLS on a five-point Likert-type scale to indicate whether they considered them to be essential, and were able to comment on each substep, using a dedicated online platform accessed by the invited tertiary care facilities that specialize in fetal therapy. Responses were returned to the panel until consensus was reached (Cronbach's α ≥ 0.80). All substeps that were rated ≥ 4 by 80% of the experts were included in the evaluation instrument. After the first iteration of the Delphi procedure, a response rate of 74% (73/98) was reached, and in the second and third iterations response rates of 90% (66/73) and 81% (59/73) were reached, respectively. Among a total of 81 substeps rated in the first round, 21 substeps had to be re-rated in the second round. Finally, from the initial list of substeps, 55 were agreed by experts to be essential. In the third round, the 18 categorized substeps were ranked in order of importance, with 'coagulation of all anastomoses that cross the equator' and 'determination of fetoscope insertion site' as the most important. A total of 55 substeps of FLS for TTTS were defined by a panel of experts to be essential in the procedure. This list is the first authority-based evidence to be used in the development of a final training model for future fetal surgeons.

Correlation between veno-venous anastomoses, TTTS and perinatal mortality in monochorionic twin pregnancies

IntroductionThe 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. MethodsAll MC placentas injected with colored dye from 2002 to 2014 were included in the study. We excluded MC pregnancies managed with fetoscopic laser surgery. Results and DiscussionA 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. ConclusionThe 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.

Cervical length in prediction of preterm birth after laser surgery for twin-twin transfusion syndrome.

To determine the risk factors for spontaneous preterm delivery (PTD) or preterm prelabor rupture of membranes (PPROM) at < 34 weeks' gestation after fetoscopic laser surgery for twin-twin transfusion syndrome and to identify the optimal threshold for preoperative cervical length (CL) that indicates a high risk for spontaneous PTD. This was a secondary analysis of data prospectively collected from 449 patients at three fetal centers. CL measurements were obtained by preoperative transvaginal ultrasound, at a gestational age of 16-26 weeks. The risk factors associated with spontaneous PTD before 34 weeks' gestation were determined using multivariable logistic regression analysis. We excluded patients with dual fetal demise and those with maternal or fetal indications for delivery without PPROM (n = 63). The optimal threshold for cervical length to predict spontaneous PTD before 34 weeks was determined using a receiver-operating characteristics (ROC) curve and Youden index. Additionally, the CL threshold for spontaneous PTD at 2-week intervals between 24 and 34 weeks was determined. Spontaneous PTD before 34 weeks occurred in 206 (53.4%) of the included patients. Only the preoperative CL was significantly associated with spontaneous PTD. The preoperative CL was normally distributed with a mean of 37.6 ± 10.3 mm (range, 5-66 mm). Maternal age and parity were positively associated, and gestational age at procedure and anterior placenta were negatively associated, with CL on multivariable linear regression analysis. The area under the ROC curve for predicting spontaneous PTD with CL measurements was 0.61 (P = 0.02) and the optimal threshold was 28 mm with a Youden index of 0.19 (sensitivity and specificity of 92% and 27%, respectively). A CL measurement of < 28 mm increased the risk of spontaneous PTD for all gestational age thresholds. Spontaneous PTD at < 34 weeks' gestation is associated with a preoperative CL of < 28 mm. Preventive strategies should focus on this high-risk group.

752: Spontaneous twin anemia-polycythemia sequence (sTAPS) with twin twin transfusion syndrome (TTTS) treatment by fetoscopic laser surgery (FLS)

sTAPS can occur as a unique disease or can complicate typical TTTS. Middle cerebral artery (MCA) Doppler studies are not currently part of the routine evaluation of monochorionic twins since they are not used in the Quintero staging system for TTTS. As such the true incidence of sTAPS remains unknown at this time. We aimed to compare the clinical characteristics and outcomes between sTAPs with or without TTTS vs. TTTS alone.

104: Altered amniotic fluid induces autophagy and cell death that leads to preterm birth after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS)

104: Altered amniotic fluid induces autophagy and cell death that leads to preterm birth after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS)