Supplementary Material for: Ultrasound-Guided Bipolar Umbilical Cord Occlusion in Complicated Monochorionic Pregnancies: Is There a Learning Curve?

Introduction: Ultrasound-guided bipolar umbilical cord occlusion (UCO) is used in complicated monochorionic multiple pregnancies in Denmark. The aim of this study was to assess a learning curve in the procedure of UCO. Materials and Methods: One hundred and two monochorionic pregnancies treated with UCO at Rigshospitalet, Denmark between 2004 and 2015 were included. The procedures were divided into period 1 (2004-2009) and period 2 (2010-2015) to determine a learning curve. Primary outcome measure was survival rate. Secondary outcome measures were time from operation to fetal loss and gestational age (GA) at delivery. Results: Period 1 included 59 cases. The median GA at procedure was 19.9 weeks (range 16.7-25.9) and at delivery 34.7 weeks (range 24.3-40.3). Period 2 included 43 cases. The median GA at procedure was 20.7 weeks (range 16.7-27.6) and at delivery 37.3 weeks (range 29.1-40.3). Survival rate increased from 78% (period 1) to 95% (period 2) (p = 0.02). GA at delivery increased as well. Fetal death within 48 h after surgery decreased from 4 (period 1) to 0 (period 2). Discussion: Our results suggest a learning curve in the procedure of UCO with improved outcome on all measures.