Objective: To determine whether using color flow Doppler to identify the umbilical cord affects amniotic fluid index (AFI) measurements.
A total of 2236 AFI measurements between 24 and 42 weeks in singleton gestations with no known or suspected fetal anomalies and < 14 days’ discrepancy between menstrual and ultrasonographic dating were included. Color flow Doppler was used to identify loops of umbilical cord; these were excluded from the measurement. Polynomial regression was used to generate means and centiles. Data were grouped according to completed weeks of gestation and descriptive statistics were calculated. At each week of gestation, the number and percentage of pregnancies diagnosed as < or = 2.5th, < or = 5th, > or = 95th, and > or = 97.5th centile according to a ‘standard’ nomogram derived without using color flow Doppler were calculated.