Diabetes mellitus in pregnancy and the assessment of umbilical artery waveforms using pulsed Doppler ultrasonography

The utility of Doppler ultrasonography as a means of assessing potential alterations of vascular resistance prior to fetal or maternal compromise is very attractive. We investigated this relationship by prospectively performing Doppler studies of the fetal umbilical artery in 56 diabetic patients, 14 of whom had varying degrees of vascular complications. When regression curves were established for the S/D ratio, the Pourcelot index, and the resistance index of the fetal umbilical artery, the mean Doppler values were higher in diabetic patients with vasculopathy than in nondiabetic control patients or in diabetic patients without vasculopathy. The third trimester S/D ratio was greater than 3.0 in almost 50% of patients with vasculopathy. A tendency toward adverse outcomes was observed at S/D ratios approaching 4.0. Statistically significant correlations were found between elevated Doppler indices and maternal vasculopathy associated with hypertension and worsening renal insufficiency. Intrauterine growth retardation and neonatal metabolic complications were also significantly correlated with elevated Doppler indices. There was, however, no correlation between Doppler indices and glucose values, although most were within a euglycemic range. The aforementioned data indicate an increased resistance circuit among diabetics with vasculopathy, which may reflect a relative reduction in basal uteroplacental blood flow and the need for cautious interpretation of Doppler indices in these patients.