Reference values for Doppler velocimetry of the ophthalmic and central retinal arteries in low-risk pregnancy

To establish reference values for Doppler velocimetry of the ophthalmic artery (OA) and the central retinal artery (CRA) in low-risk pregnancy.

Between January 2008 and March 2009, 63 low-risk pregnant women underwent an ultrasound scan every 2 weeks at the Women's Hospital, Campinas, Brazil, to determine the resistance index (RI), pulsatility index (PI), and peak systolic velocity of both arteries, in addition to the flow velocity of the second peak and peak ratio (PR) of the OA. For analysis, linear regression was used with mixed models for longitudinal data, coefficient of determination, and estimates of the 5th and 95th percentiles for each parameter at each gestational age. Intra- and inter-observer variability was evaluated via the intraclass correlation coefficient.

There was a trend of a reduction with gestational age in PI and RI of the OA, and PI of the CRA, but not in PR of the OA; and the respective reference values were established. Intra- and inter-observer variability was considered satisfactory.

Unilateral assessment of the orbital Doppler velocimetry is feasible. Establishment of reference values showed a negative correlation between gestational age and PI and RI of the OA, and PI of the CRA. The method demonstrated satisfactory reproducibility.