Internal jugular vein blood flow in normal and growth-restricted fetuses

Objective: To assess internal jugular vein blood now patterns during the se cond half of pregnancy in normal and growth-restricted fetuses. Methods: We did Doppler ultrasound studies of internal jugular veins and th e inferior vena cavas longitudinally on 21 normal singleton fetuses from 20 weeks to term, and on eight growth-restricted fetuses with absent end-dias tolic flow at the umbilical artery (UA). The three components of the venous flow velocity waveforms were used to calculate peak velocity ratio: Peak s ystolic velocity (S wave) minus reverse peak velocity (R wave) divided by p eak velocity during early diastole (D wave) and velocity time integral rati o: systolic velocity time integral minus reverse velocity time integral div ided by velocity time integral during early diastole. Statistical analysis of longitudinal measurements used K-related samples Friedman test; groups w ere compared with Mann-Whitney U test and chi(2) test. Results: In normal fetuses we found significant increases in peak velocity ratio and velocity time integral ratio of internal jugular veins and the in ferior vena cavas throughout gestation. The mean +/- standard deviation (SD ) of the internal jugular veins peak velocity ratio (1.12 +/- 0.4 versus 1. 46 +/- 0.15, P < .05) and velocity time integral ratio (1.1 +/- 0.2 versus 1.55 +/- 0.17, P < .05) were significantly lower in growth-restricted fetus es compared with normal fetuses at 28-32 weeks' gestation but inferior vena cava indices were not. None of the eight growth-restricted fetuses had umb ilical venous pulsations or changes in inferior vena cava or ductus venosus blood flow patterns. All had arterial pH above 7.15 at birth. Conclusion: Growth-restricted fetuses with absent end-diastolic velocity in the UA have changes in internal jugular vein blood flow patterns that prob ably indicate increased cerebral blood flow, more evidence of redistributio n of blood flow in growth-restricted fetuses that can be used to maintain t hem. (C) 2000 by The American College of Obstetricians and Gynecologists.