Journal of Ultrasound in Medicine, Vol 20, Issue 11 1183-1188, Copyright © 2001 by American Institute of Ultrasound in Medicine
Early second-trimester low umbilical coiling index predicts small-for-gestational-age fetuses
S. Degani, Z. Leibovich, I. Shapiro, R. Gonen and G. Ohel
Department of Obstetrics and Gynecology, Bnai Zion Medical Center, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
OBJECTIVE: To evaluate the role of the early second-trimester Doppler
velocimetric studies of the umbilical coiling index and umbilical cord
cross-sectional area as tests for the prediction of small-for-gestational
age infants. METHODS: Doppler blood flow studies in 147 singleton
pregnancies at risk for delivery of a small-for-gestational-age neonate
were performed at 15 +/- 1 (SD) weeks' gestation from the uterine artery,
umbilical artery, middle cerebral artery, inferior vena cava, and ductus
venosus. Pulsatility index values were calculated for the arteries, and
preload index values and systolic-atrial contraction ratios were calculated
for the veins. The sonographic cross-sectional area of the umbilical cord
was measured in a plane adjacent to the insertion into the fetal abdomen.
The umbilical coiling index was calculated by using sonographic
longitudinal views of cord vessels from several segments antenatally and by
dividing the total number of helices by cord length (centimeters)
postnatally. Small-for-gestational-age neonates were identified when the
birth weight was below the 10th percentile for gestational age. RESULTS:
Among 147 pregnancies studied, 124 fulfilled the study criteria.
Thirty-nine of the neonates were small for gestational age at birth
(31.5%). The mean +/- SD gestational age at delivery of the
appropriate-for-gestational-age neonates was 39.7 +/- 1.28 weeks, and that
of the small-for-gestational-age neonates was 36.4 +/- 2.9 weeks (range,
28-40 weeks). The best single predictor of a small-for-gestational-age
infant was the coiling index, with sensitivity of 79%, specificity of 86%,
a positive predictive value of 72%, and a negative predictive value of 90%.
CONCLUSIONS: The umbilical coiling index measured in the second trimester
is useful in predicting the birth of a small-for-gestational-age infant and
may serve as a marker for subsequent growth restriction.
