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.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

A worldwide survey of laser surgery for twin-twin transfusion syndrome

OBJECTIVES

To evaluate differences between international fetal centers in their treatment of twin-twin transfusion syndrome (TTTS) by fetoscopic placental laser coagulation.

METHODS

Fetal therapy centers worldwide were sent a web-based questionnaire. Participants were identified through networks and through scientific presentations and papers. Questions included physician and center demographics, treatment criteria, operative technique and instrumentation. Laser treatment was compared between low-volume (< 20 procedures/year) and high-volume (≥ 20 procedures/year) centers. Data were analyzed using descriptive statistics.

RESULTS

Of 106 fetal therapy specialists approached, 76 (72%) from 64 centers in 25 countries responded. Of these, 48% (31/64) of centers and 63% (48/76) of operators performed fewer than 20 laser procedures annually. Comparison of low- and high-volume centers showed differences in technique, gestational age limits for treatment and geography. High-volume centers more often used the Solomon technique and applied wider gestational age limits for treatment. Europe and Asia had more high-volume centers, whereas South America, the Middle East and Australia had mainly low-volume centers.

CONCLUSION

This survey revealed significant differences between fetal centers in several aspects of fetoscopic placental laser therapy for TTTS. Increasing awareness of TTTS, and of laser coagulation as its preferred treatment, will lead to an increase in centers offering this modality, especially in Asia, Africa, South America and the Middle East. Considering the rarity of TTTS and the relative complexity of the procedure, developing international guidelines for techniques, instrumentation and suggested minimum volumes per center may aid in optimizing perinatal outcome.

Iatrogenic perforation of intertwin membrane after laser surgery for twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate management and outcome of iatrogenic monoamniotic twins (iMAT) compared with twins with intact intertwin dividing membranes after laser surgery for twin-to-twin transfusion syndrome (TTTS).

METHODS

This was a retrospective analysis of twins with and without iatrogenic rupture of the intertwin membranes that had been treated for TTTS with laser surgery at our center between 2004 and 2012. Primary outcomes were perinatal survival and severe neonatal morbidity. Secondary outcomes were mode of delivery, gestational age at birth and cord entanglement.

RESULTS

In total, 338 pregnancies were included. In 67/338 (20%) pregnancies, iMAT was suspected antenatally. In 47 of these 67 (70%), a preterm Cesarean section was performed for monoamnionicity. Perinatal survival was 108/134 (81%) vs 396/542 (73%) in twins with intact intertwin membranes (P = 0.13). Mean gestational age at birth in iMAT was 31 completed weeks, compared to 33 weeks in twins with intact membranes (P < 0.01). At birth, cord entanglement was present in 8/67 (12%) iMAT pregnancies. Severe neonatal morbidity was assessed in 106/110 (96%) in iMAT cases and 392/416 (94%) in controls. The incidence of severe neonatal morbidity was 28/106 (26%) in iMAT vs 72/392 (18%) in controls (P = 0.25). Severe cerebral injury was significantly increased in the iMAT group as compared with controls, at 16/106 (15%) vs 18/392 (5%) (P < 0.01).

CONCLUSIONS

Iatrogenic rupture of intertwin membranes was suspected in 20% of pregnancies treated with laser therapy for TTTS and was associated with a lower gestational age at birth and increased neonatal morbidity.

Laser surgery as a management option for twin anemia-polycythemia sequence

OBJECTIVE

To evaluate the effectiveness of laser treatment for antenatally detected twin anemia-polycythemia sequence (TAPS) compared with intrauterine transfusion or expectant management.

METHODS

All monochorionic twin pregnancies with TAPS managed between 2005 and 2013 in two European fetal therapy centers were evaluated. The outcomes of TAPS cases treated primarily with laser surgery were compared with the outcomes of cases managed expectantly or treated with intrauterine transfusion.

RESULTS

In this retrospective study 52 cases of TAPS were detected antenatally and were managed with either laser surgery (n=8; 15%) or intrauterine blood transfusion (n=17; 33%) or expectantly (n=27; 52%). Perinatal survival in the laser group was 94% (15/16) vs 85% (29/34) in the intrauterine-transfusion group and 83% (45/54) in the expectant-management group (P=0.30). The rates of severe neonatal morbidity in liveborn neonates in the laser, intrauterine-transfusion and expectant-management groups were 7% (1/15), 38% (12/32) and 24% (12/50), respectively (P=0.17). There was a significant reduction in respiratory distress syndrome in cases treated by laser. No severe postnatal hematological complications were detected in the laser group compared with 72% (23/32) in the intrauterine-transfusion group and 52% (26/50) in the expectant-management group (P<0.01). Median time between diagnosis and birth was 11 weeks in the laser group compared to 5 weeks after intrauterine transfusion and 8 weeks after expectant management (P<0.01). After injection of colored dye no residual anastomoses were found in the laser group.

CONCLUSIONS

Laser surgery for TAPS appears to improve perinatal outcome by prolonging pregnancy and reducing respiratory distress syndrome. Larger, adequately controlled studies are needed to reach firm conclusions on the optimal management of TAPS.