Improving Sonographic Evaluation of the Umbilical Cord at the Second-Trimester Anatomy Scan

Abstract

Received November 18, 2008, from the Fetal Medicine Center, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile. Revision requested December 15, 2008. Revised manuscript accepted for publication February 9, 2009. This work was supported by the Sociedad Profesional de Medicina Fetal “Fetalmed” Limitada, Chile. Address correspondence to Waldo Sepulveda, MD, Fetal Medicine Center, Clinica Las Condes, Casilla 208, Santiago 20, Chile. E-mail: fetalmed@yahoo.com Abbreviations UCI, umbilical coiling index urrent guidelines for second-trimester sonographic examination recommend evaluation of the fetal anatomy and growth, placental location, and amniotic fluid volume and examination of the umbilical cord by trained sonographers.1,2 Umbilical cord assessment is routinely limited to the cord vessel number because a single umbilical artery is well established to be linked with poor pregnancy outcomes.3 However, a substantial number of obstetric complications may arise from other conditions involving the placenta and umbilical cord.4,5 Indeed, a poor perinatal outcome has been associated with other characteristics of the umbilical cord, such as being thin,6 having a velamentous insertion,7 and abnormal coiling.8,9 We report the practice of a systematic approach to the assessment of the umbilical cord during the secondtrimester anatomy scan and propose a new sonographic classification system of umbilical cord coiling. Our method assessed the following 4 characteristics of the umbilical cord: 1. Evaluation of the number of vessels—The umbilical cord was imaged in cross section and magnified to visualize the number of vessels. If the vessel number was uncertain because of suboptimal views, color flow imaging of the intra-abdominal vessels running alongside the fetal bladder was available to confirm the presence of 2 umbilical arteries.3,5 2. Measurement of the umbilical cord area—To assess the amount of Wharton jelly protecting the umbilical vessels, a mid segment of the umbilical cord was visualized in cross section, and the area was measured using the software of the ultrasound machine (Figure 1). These measurements were then compared with an established umbilical cord area nomogram.10