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

Computer-assisted fetal laser surgery in the treatment of twin-to-twin transfusion syndrome recent trends and prospects

Fetal laser surgery has emerged as the preferred treatment of twin-to-twin transfusion syndrome (TTTS). However, the limited field of view of the fetoscope and the complexity of the procedure make the treatment challenging. Therefore, preoperative planning and intraoperative guidance solutions have been proposed to cope with these challenges. This review uncovers the literature on computer-assisted software solutions focused on TTTS. These solutions are classified by the pre- or intraoperative phase of the procedure and further categorized by discussed hardware and software approaches. In addition, it evaluates the current maturity of technologies by the technology readiness level and enumerates the necessary aspects to bring these new technologies to the clinical practice. This article is protected by copyright. All rights reserved.

Twin-Twin Transfusion Syndrome Complicated by Proximate Placental Cord Insertion Sites: Endoscopic Clip-Assisted Laser Occlusion

INTRODUCTION

Severe twin-twin transfusion syndrome (TTTS) with a large vascular communication between proximate placental cord insertion sites is a therapeutic dilemma because laser ablation may cause thermal injury to the cord roots and subsequent fetal demise.

CASE PRESENTATION

Stage IV TTTS with placental cord insertion sites 1.3 cm apart and with an intervening large arterio-arterial (AA) anastomosis presented for treatment. The application of endoclips onto the large AA anastomosis between the cord roots allowed for successful laser occlusion using minimal energy. Both the donor and recipient twins were alive and well at 6 months of age.

CONCLUSION

Endoscopic clip-assisted laser occlusion of a placental vessel is technically feasible and may be a useful therapeutic option in select cases.

Selective intrauterine growth restriction (SIUGR) type II: proposed subclassification to guide surgical management

Background: Optimal surgical management of monochorionic diamniotic twins complicated by selective intrauterine growth restriction (SIUGR) type II is unknown. Surgical management may involve selective laser photocoagulation of communicating vessels (SLPCV), which offers the possibility of dual twin survivors versus umbilical cord occlusion (UCO) of the SIUGR twin.Objective: To identify patient characteristics associated with SIUGR twin survival for those undergoing SLPCV.Study design: All patients studied were those who underwent fetal treatment for SIUGR type II at our center from 2006-2018. SIUGR type II was defined as an estimated fetal weight <10th percentile with persistent absent and/or reversed end diastolic flow in the umbilical artery of the SIUGR twin, in the absence of twin-twin transfusion syndrome. Patients were offered SLPCV versus UCO, and those undergoing SLPCV, patient characteristics associated with 30-day survival of the SIUGR twin were examined using bivariate analysis and multiple logistic regression models.Results: Fifty-four consecutive SIUGR type II patients were treated, 45 via SLPCV and nine via UCO. Of the 45 SLPCV cases, there were 16 (35.6%) with SIUGR twin (and dual) survival. SIUGR twin survival appeared associated with middle cerebral artery (MCA) peak systolic velocity (psv) <1.5 multiples of the median, and forward atrial systolic flow in the ductus venosus (DV). In a post hoc analysis, we subsequently categorized patients as: SIUGR type IIa (N = 32 (71.1%)): normal MCA psv, and normal DV waveform, versus SIUGR type IIb (N = 13 (28.9%)): MCA psv ≥1.5 multiples of the median, and/or DV with absent or reversed atrial systolic flow. Thirty-day survival of the SIUGR twin was 50% for type IIa and 0% for type IIb.Conclusion: Over one-third of SIUGR type II patients experienced dual survival after treatment with laser surgery. Normal MCA psv and normal DV waveforms were associated with SIUGR type II survival of the SIUGR twin. Post hoc exploration and subclassification of SIUGR type II patients by preoperative Doppler indices created two groups, one (type IIa) with 50% survival and one (type IIb) with 0% survival of the SIUGR twin after laser surgery. Upon further confirmation, these findings may provide guidance for counseling patients and conducting fetal therapy.

Model Surgical Training: Skills Acquisition in Fetoscopic Laser Photocoagulation of Monochorionic Diamniotic Twin Placenta Using Realistic Simulators

Fetoscopic laser coagulation of arterio-venous anastomoses (AVA) in a monochorionic placenta is the standard of care for twin-twin transfusion syndrome (TTTS), but is technically challenging and can lead to significant complications. Acquiring and maintaining the necessary surgical skills require consistent practice, a critical caseload, and time. Training on realistic surgical simulators can potentially shorten this steep learning curve and enables several proceduralists to acquire procedure-specific skills simultaneously. Here we describe realistic simulators designed to allow the user familiarity with the equipment and specific steps required in the surgical treatment of TTTS, including fetoscopic handling, approaches to anterior and posterior placenta, recognition of anastomoses, and efficient coagulation of vessels. We describe the skills that are especially important in conducting placental laser coagulation that the surgeon can practice on the model and apply in a clinical case. These models can be adapted easily depending on the availability of materials and require standard fetoscopy equipment. Such training systems are complementary to traditional surgical apprenticeships and can be useful aids for fetal medicine units that provide this clinical service.

Rapid initiation of fetal therapy services with a system of learner-centred training under proctorship: the National University Hospital (Singapore) experience

INTRODUCTION

Management of complicated monochorionic twins and certain intrauterine structural anomalies is a pressing challenge in communities that still lack advanced fetal therapy. We describe our efforts to rapidly initiate selective feticide using radiofrequency ablation (RFA) and selective fetoscopic laser photocoagulation (SFLP) for twin-to-twin transfusion syndrome (TTTS), and present the latter as a potential model for aspiring fetal therapy units.

METHODS

Five pregnancies with fetal complications were identified for RFA. Three pregnancies with Stage II TTTS were selected for SFLP. While RFA techniques utilising ultrasonography skills were quickly mastered, SFLP required stepwise technical learning with an overseas-based proctor, who provided real-time hands-off supervision.

RESULTS

All co-twins were live-born following selective feticide; one singleton pregnancy was lost. Fetoscopy techniques were learned in a stepwise manner and procedures were performed by a novice team of surgeons under proctorship. Dichorionisation was completed in only one patient. Five of six twins were live-born near term. One pregnancy developed twin anaemia-polycythaemia sequence, while another was complicated by co-twin demise.

DISCUSSION

Proctor-supervised directed learning facilitated the rapid provision of basic fetal therapy services by our unit. While traditional apprenticeship is important for building individual expertise, this system is complementary and may benefit other small units committed to providing these services.

Impact of Laser Power and Firing Angle on Coagulation Efficiency in Laser Treatment for Twin-Twin Transfusion Syndrome: An ex vivo Placenta Study

OBJECTIVE

To assess the impact of laser power and firing angle on coagulation efficiency for closing placental anastomoses in the treatment of twin-twin transfusion syndrome.

METHODS

We used an ex vivo blood-perfused human placenta model to compare time to complete coagulation using 30 vs. 50 W of neodymium-doped yttrium aluminum garnet laser power and using a firing angle of 90° vs. 45°. Placentas were perfused with pig blood at 5 mL/min. Differences were analyzed using independent-samples t test, Mann-Whitney U test, or χ2 test as appropriate.

RESULTS

Coagulation took less time and energy using 50 W (n = 53) compared to 30 W (n = 52), 11 vs. 22 s (p < 0.001), and 557 vs. 659 J (p = 0.007). Perpendicular coagulation (n = 53) took less time and energy compared to a 45° angle (n = 21), 11 vs. 17 s (p = 0.004), and 557 vs. 871 J (p = 0.004). Bleeding complicated 2 (3%) measurements in the 50-W group, 5 (10%) in the 30-W group, and 3 (14%) in the 45° group.

DISCUSSION

In a highly controlled model, a 50-W laser power setting was more energy efficient than 30 W in coagulating a placental vein. A more perpendicular laser firing angle resulted in more efficient coagulation. Furthermore, bleeding due to vessel wall disruption occurred more often with lower power and a more tangential approach.

Prior uterine bleeding is associated with low visibility due to discolored amniotic fluid on fetoscopic laser photocoagulation

AIM

To investigate the association between uterine bleeding preceding fetoscopic laser photocoagulation (FLP) and the presence of discolored amniotic fluid that impedes FLP.

METHODS

A retrospective review of all multiple gestations requiring FLP at the present institution was conducted. The rate of low visibility because of discolored amniotic fluid at the beginning of FLP was compared between patients with and without a history of uterine bleeding, defined as either genital bleeding or ultrasonographically detected subchorionic hematoma.

RESULTS

The prevalence of low visibility because of discolored amniotic fluid was 4.5% (seven in 156 patients). Two of the seven cases of low visibility resulted in double fetal death. The incidence of low visibility was significantly higher in the group with uterine bleeding before surgery compared with that without bleeding (28.6% vs 0.74%, P < 0.001).

CONCLUSIONS

Patients with a history of uterine bleeding prior to FLP may encounter more technical difficulties owing to discolored amniotic fluid during FLP.

Laser Treatment of Twin–to–Twin Transfusion Syndrome

Objective: Laser ablation of all placental vascular anastomoses is the optimal treatment for twin–twin transfusion syndrome (TTTS). However, two important controversies are apparent in the literature: (a) a gap between concept and performance, and (b) controversy regarding whether all the anastomoses can be identified endoscopically and whether blind lasering of healthy placenta is justified. The purpose of this article is: (a) to address the potential source of the gap between concept and performance by analyzing the fundamental steps needed to successfully accomplish the surgery, and (b) to discuss the resulting competency benchmarks reported with the different surgical techniques. Materials and Methods: Laser surgery for TTTS can be broken down into two fundamental steps: (1) endoscopic identification of the placental vascular anastomoses, (2) laser ablation of the anastomoses. The two steps are not synonymous: (a) regarding the endoscopic identification of the anastomoses, the non-selective technique is based upon lasering all vessels crossing the dividing membrane, whether anastomotic or not. The selective technique identifies and lasers only placental vascular anastomoses. The Solomon technique is based on the theory that not all anastomoses are endoscopically visible and thus involves lasering healthy areas of the placenta between lasered anastomoses, (b) regarding the actual laser ablation of the anastomoses, successful completion of the surgery (i.e., lasering all the anastomoses) can be measured by the rate of persistent or reverse TTTS (PRTTTS) and how often a selective technique can be achieved. Articles representing the different techniques are discussed. Results: The non-selective technique is associated with the lowest double survival rate (35%), compared with 60–75% of the Solomon or the Quintero selective techniques. The Solomon technique is associated with a 20% rate of residual patent placental vascular anastomoses, compared to 3.5–5% for the selective technique (p < .05). Both the Solomon and the selective technique are associated with a 1% risk of PRTTTS. Adequate placental assessment is highest with the selective technique (99%) compared with the Solomon (80%) or the ‘standard’ (60%) techniques (p < .05). A surgical performance index is proposed. Conclusion: The Quintero selective technique was associated with the highest rate of successful ablation and lowest rate of PRTTTS. The Solomon technique represents a historical backward movement in the identification of placental vascular anastomoses and is associated with higher rate of residual patent vascular communications. The reported outcomes of the Quintero selective technique do not lend support to the existence of invisible anastomoses or justify lasering healthy placental tissue.

Balancing Patient Access to Fetoscopic Laser Photocoagulation for Twin-to-Twin Transfusion Syndrome With Maintaining Procedural Competence: Are Collaborative Services Part of the Solution?

The benefits of fetoscopic laser photocoagulation (FLP) for treatment of twin-to-twin transfusion syndrome (TTTS) have been recognized for over a decade, yet access to FLP remains limited in many settings. This means at a population level, the potential benefits of FLP for TTTS are far from being fully realized. In part, this is because there are many centers where the case volume is relatively low. This creates an inevitable tension; on one hand, wanting FLP to be readily accessible to all women who may need it, yet on the other, needing to ensure that a high degree of procedural competence is maintained. Some of the solutions to these apparently competing priorities may be found in novel training solutions to achieve, and maintain, procedural proficiency, and with the increased utilization of 'competence based' assessment and credentialing frameworks. We suggest an under-utilized approach is the development of collaborative surgical services, where pooling of personnel and resources can improve timely access to surgery, improve standardized assessment and management of TTTS, minimize the impact of the surgical learning curve, and facilitate audit, education, and research. When deciding which centers should offer laser for TTTS and how we decide, we propose some solutions from a collaborative model.

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Twenty-Five Years of Fetoscopic Laser Coagulation in Twin-Twin Transfusion Syndrome: A Systematic Review

Objective: The aim of this study was to assess the perinatal outcome of pregnancies with twin-twin transfusion syndrome (TTTS) treated with laser therapy over the past 25 years, and in relation to different techniques used in this time period. Methods: A systematic review of studies reporting on perinatal outcome according to the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines was conducted. The MEDLINE, Embase and Cochrane Library databases were systematically searched. Comparisons were made in respect to time period and laser technique and Quintero stages. Results: In total, 34 studies reporting on 3,868 monochorionic twin pregnancies were included. The mean survival of both twins increased from 35 to 65% (p = 0.012) and for at least one twin from 70 to 88% (p = 0.009) over the past 25 years. Mean gestational age at birth remained stable over the years at 32 weeks gestation. Also, we showed a significantly improved perinatal survival with the evolution of the laser technique from non-selective to selective, selective sequential and the Solomon technique (p = 0.010). Discussion: Since the introduction of laser therapy for TTTS more than two decades ago, perinatal survival improved significantly. Improved outcome is probably associated with several factors, including evolution of the laser technique, learning curve effect, better referral and improved early neonatal care.