Longitudinal umbilical vein blood flow changes in normal and growth-retarded fetuses

Objective. To explore whether the umbilical vein blood flow of growth-retarded fetuses with normal Doppler parameters changes over time differently to that of normally grown fetuses. Methods. Fifteen consecutive women whose fetus was diagnosed to be growth restricted were compared with 30 women whose fetus was normally grown. Two ultrasonographic evaluations were conducted at 2-weekly intervals (± 2 days) in all cases. At each sonographic evaluation, umbilical vein blood flow parameters were obtained by digital color Doppler velocity profile integration. To allow comparisons among fetuses, the umbilical vein blood flow per minute was normalized for abdominal circumference. Results. The absolute vein blood flow was lower in growth-retarded than in normally grown fetuses (209 ml/min ± 73 vs. 313 ml/min ± 72, p < 0.01). The median (range) umbilical vein blood flow normalized for abdominal circumference was significantly lower in growth-retarded than in normally grown fetuses at the first [0.70 (0.32; 1.15) vs. 1.11 (0.65; 2.07), p < 0.05] and at the second [0.71(0.30; 1.09) vs. 1.14 (0.69; 2.05), p < 0.05] sonographic evaluation. The difference in umbilical vein blood flow normalized for abdominal circumference between the second and the first examination was significantly lower in growth-retarded than in appropriate for gestational age fetuses [-0.005 (-0.08; 0.06) vs. 0.02 (-0.08; 0.1), p < 0.05]. Conclusion. This study demonstrates that umbilical vein blood flow normalized for biometric parameters is lower in growth-retarded fetuses than in healthy fetuses even in the absence of umbilical artery Doppler abnormalities.