Ultrasound estimate of amniotic fluid volume: Color Doppler overdiagnosis of oligohydramnios

Objective: To determine if concurrent use of color Doppler affects ultrasou nd estimates of amniotic fluid (AF) volume. Methods: Study gravidas underwent ultrasound estimations of AF volume subje ctively (visualization without measurements) and objectively (using amnioti c fluid index: [AFI]) and single-deepest pocket techniques, without and wit h concurrent color Doppler. Amniocentesis with the dye-dilution technique t o measure actual AF volume was utilized for comparison. Results: Sixty-seven women at a mean gestational age of 37.1 +/- 2.5 weeks were entered into this investigation between June 1999 and March 2000. Dye- determined AF volume was classified as low in 18 patients and as high in se ven, with the remaining 42 within normal range. Using either ultrasound tec hnique with color Doppler produced significantly lower estimates of AF volu me (9.3 +/- 4.9) compared to those without color ([11.6 +/- 5], P < .001) f or the AFI and (3.7 +/- 1.5) with color compared to those without color ([4 .5 +/- 1.5], P < .003) for the single-deepest pocket. Using AFI without col or identified two of 67 (3%) of the pregnancies as having low fluid compare d to 14 of 67 ([21%] P .002) using color. The increased classification of o ligohydramnios with color did not accurately identify a greater number of d ye-determined low volumes; instead, the AFI with color mislabeled nine preg nancies with normal fluid as low. The diagnosis of dye-determined low and h igh fluid volumes was not significantly different with or without color. Conclusion: Concurrent use of color Doppler with AFI measurements leads to the overdiagnosis of oligohydramnios. (C) 2001 by the American College of O bstetricians and Gynecologists.