Comparison of the amniotic fluid index with gray-scale and color Doppler ultrasound.

OBJECTIVES

This study was undertaken to compare the amniotic fluid index (AFI) obtained with gray-scale ultrasound and color Doppler.

STUDY

DESIGN

We examined 77 patients ranging from 22 to 41 weeks' gestation with two of five sonographers obtaining two measures of the AFI utilizing gray-scale and color Doppler.

RESULTS

Of the measurements of AFI, 96% showed the gray scale measurement to be greater than the color measurement (p < 0.0001; mean 9.3 +/- 3.3 cm vs. 8.5 +/- 3.0 cm). At gray-scale AFI < 5 cm, color AFI was essentially the same, but at gray-scale AFI 5-10 cm, color AFI was < 5 cm, 15.2% and 7.8% of the time. At gray-scale AFI > 10 cm, no color AFI was < 5 cm. Individual (n = 5) interobserver reliability was r = 0.79 (p < 0.0001) and intraobserver reliability was r = 0.94 (p < 0.0001).

CONCLUSIONS

AFI by color Doppler was always less than with gray scale. At an AFI of 5-10 cm, color demonstrated an AFI of < 5 cm in up to 16% of patients, and increased the diagnosis of oligohydramnios.