Abstract
Introduction: Limited data exist regarding the effect of pre-operative risk factors on fetal survival for patients undergoing fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome (TTTS). The primary objective of this study was to determine the pre-operative variables predictive of single and dual fetal survival at birth for subjects treated with laser for TTTS. The secondary objective was to determine the combined effect of multiple risk factors on single and dual fetal survival at birth. Methods: This was a prospective cohort study of TTTS pregnancies treated with FLP between 2001 and 2023. Cases were identified through the Monochorionic Twin Pregnancy Registry of the North American Fetal Therapy Network. Several pre-operative risk factors were evaluated, including maternal body mass index, gestational age at laser, fetal growth restriction (FGR), cervical length, placental location, and TTTS stage. Higher order multiples, fetal anomalies, karyotypic abnormalities, and cases with missing data were excluded. Risk factors influencing survival were assessed with uni- and multi-variate regression analyses. The predicted probability of single/dual survival based on these risk factors was assessed with multiple logistic regression analysis. Results: Of 2,728 FLP cases, 1,066 met inclusion criteria. Dual survival is reduced in stage 3 and 4 disease compared to stage 1 and 2 (OR 0.75: 0.58, 0.98; p = 0.032) with the lowest survival in all stages occurring with FGR. An anterior placenta (aOR 0.58: 0.37, 0.91; p = 0.017) and FGR <10th percentile (aOR 0.57: 0.35, 0.92; p = 0.02) were independent predictors of reduced survival. With regression modeling, sequential addition of any pre-operative risk factor progressively reduces survival of at least one or both twins. Conclusions: In this large registry, anterior placental location and FGR were most predictive of reduced survival for both twins. As the number of pre-operative risk factors increases for a given TTTS case, there is a progressive reduction in survival probability and these reported probability rates may be useful in counseling patients.
Plain Language Summary
Twin-twin transfusion syndrome (TTTS) results from unbalanced blood flow between identical twins through connecting surface vessels of the single shared placenta. Multiple complications can arise from one twin receiving too little blood volume and its co-twin receiving too much blood volume. When TTTS is severe enough, fetoscopic laser ablation of these connecting vessels can markedly improve survival. Understanding the chance for survival of at least one twin or both twins is important prior to surgery for patient counseling. The current study assessed multiple potential risk factors identified prior to surgery and the impact of these factors on survival as individual risk factors and when combined. In this large registry of over 1,000 eligible TTTS cases, anterior placental location and fetal growth restriction were most predictive of reduced survival for both twins. As the number of pre-operative risk factors increases for a given TTTS case, there is a progressive reduction in survival. Predicted probability rates based on the presence of one or more pre-operative risk factors may be useful in counseling patients.
