- Visual Inspection
It has been shown that the subjective estimate of the amniotic fluid volume could be as accurate as the semi-quantitative measurements (Magann et al., 1997). This technique is adequate for use during early gestation.
- Single Deepest Pocket (SDP)
The measurement is performed with the ultrasound probe at a right angle with the uterine wall. Measurements should exclude the umbilical cord or fetal parts. The width of each measured pocket must be at least 1 cm. Normal values range between 2-8 cm. It is also the preferred method for estimating the amniotic fluid volume in twin pregnancies.
Both semi-quantitative measurement techniques correlate poorly with the actual amniotic fluid volume.
- Amniotic Fluid Index (AFI)
- Magann, E. F., Perry, K. G., Chauhan, S. P., Anfanger, P. J., Whitworth, N. S. and Morrison, J. C. (1997), The accuracy of ultrasound evaluation of amniotic fluid volume in singleton pregnancies: The effect of operator experience and ultrasound interpretative technique. J. Clin. Ultrasound, 25: 249-253. doi:10.1002/(SICI)1097-0096(199706)25:5<249::AID-JCU5>3.0.CO;2-D
- Reddy, U. M., Abuhamad, A. Z., Levine, D., & Saade, G. R. (2014). Fetal Imaging. Journal of Ultrasound in Medicine, 33(5), 745–757. https://doi.org/10.7863/ultra.33.5.745
- Nabhan AF, Abdelmoula YA. Amniotic fluid index versus single deepest vertical pocket as a screening test for preventing adverse pregnancy outcome. Cochrane Database Syst Rev 2008; 3:CD006593. doi:10.1002/14651858.CD006593.pub2.