EP18.06: Outcomes of cytogenetic analysis during fetoscopic selective laser photocoagulation for Twin–twin transfusion syndrome

Twin pregnancies have a higher risk of structural anomalies when compared to singleton pregnancies and 15% of monochronic twin pregnancies are complicated by Twin–twin transfusion syndrome (TTTS). During fetoscopic selective laser photocoagulation (FSLP), amnioreduction is performed and fetal cytogenetics may be assessed. Our aim was to uncover the risk of abnormal cytogenetic results and their implications. Patients undergoing FSLP at our centre for TTTS were offered cytogenetic analyses from amniotic fluid collected intraoperatively. Results were characterised as normal, abnormal, true mosaicism or confirmed parental variants. Additional demographic information was obtained from electronic medical records. Trends of patient acceptance and provider documentation of genetic counselling was also determined. 417 patients underwent FSLP at our Fetal Center with documented genetic counselling (see figure 1). Of these, 78% (325/417) consented to amniotic fluid cytogenetic analysis, 292 Karyotypes (89.8%) and 33 CMAs (10.2%). Karyotypes had a 2% (8/292) culture failure rate with 1 abnormal result (0.34%), 2 true mosaics (0.68%) and 281 normal results (95.8%). CMA analysis showed in 1 abnormal (47 XXX, 3%) and 32 normal results (97%). Abnormal results were not associated with preoperative ultrasonographic findings. Six confirmed parental variants were encountered. Cytogenetic analysis at time of FSLP for monochronic twins is feasible and may provide additional information to parents. Thus, potential benefits must be weighed against the identification of unidentified parental variants and unknown consanguinity, taking into consideration patients desires and goals. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.