Proximate Cord Insertion in Twin-to-Twin Transfusion Syndrome: Case Series and PRISMA Compliant Systematic Review and Meta-Analysis

Objective: We aimed to investigate the prevalence and clinical outcomes of twin-to-twin transfusion syndrome (TTTS) with proximate cord insertions. Methods: This was retrospective cohort study of TTTS cases managed at single fetal center between 2012 and 2020. Presence of proximate cord insertions was defined as a distance of equal or less than 4 cm between placental cord insertions that was recorded based on sonographic and fetoscopic examinations. Clinical outcomes were investigated compared to unmatched cohort and to 1:2 matched controls using preoperative variables including Quintero staging, selective fetal growth restriction, anterior placenta, preoperative cervical length, and gestational age at fetal intervention. Systematic review and meta-analysis were conducted following PRSMA guidelines through searching PubMed, Scopus, CINAHL, and Medline databases from inception until January 2021. Results: The prevalence of proximate cord insertions in monochorionic placentas with TTTS was 2% (5/246). All 5 cases were managed by fetoscopic laser surgery (FLS). Procedure time was significantly longer (mean: 61.4 min in proximate cord vs. 37.5 min in nonproximate cord, p < 0.001), and amnioinfusion was significantly more common (100% in proximate cord vs. 43% in nonproximate cord, p = 0.01). Perinatal survival and neonatal outcomes were not different between groups. Similar findings were seen following 1:2 control matching. Systematic review yielded total of 19 case reports of which different management options were applied including FLS (n = 13), amniodrainage (n = 3), and selective reduction (n = 3). Clinical outcomes results were mixed and inconsistent. FLS was described as technically challenging and residual anastomosis was common. Overall fetal and neonatal survival following FLS was 85% and 80%, respectively. Conclusion: Presence of proximate cords in TTTS cases poses serious technical challenges even for highly experienced surgeons. Feasibility should be only determined by fetoscopic examination.