Implications of Differences in Coiling Indices at Different Segments of the Umbilical Cord

The purpose of this study was to find out if the coiling density is similar in all segments of term singleton umbilical cords. We compared the coiling index (coils/cm) at three different segments of 159 cords. There was no statistical difference between the coiling indices of the placental and middle segment, but significantly increased coiling was found at the fetal end compared with the placental and middle segments. Coiling indices were not significantly correlated with gestational age, cord length or birth weight. We diagnosed concordant hypo- and hypercoiling when the placental and fetal segments had the same density classification, and discordant hypo- and hypercoiling when these segments had different density classifications. Concordant hypocoiling and hypercoiling were found in 4.4 and 6.3% of the cords examined, respectively (total of 10.7%), concordant normal coiling in 95 (59.7%) and discordant density classifications in 29.6%. We concluded that the coiling index should be established in two distinct segments and that the spatial configuration of the coils, which protects the blood flow in the umbilical cord, might not be measured by coil density only.