Volumetric determination of placental and uterine growth relationships from B-mode ultrasound by serial area-volume determinations.

Serial area-volume determinations may be made from B-mode ultrasonography. Multiple sonographic sections are taken through a structure of interest. The area of the structure of interest is determined on each sonographic section by a form of planimetry and multiplied by the step-interval to obtain the volume of the structure of interest between sonographic sections. The total volume of the structure of interest is the sum of the individual volumes. The volume is computed from both transverse and longitudinal images and an average obtained for improved accuracy. Total intrauterine volume and placental volume were determined by the serial area-volume method in 63 normal patients and the results were analyzed. Placental and total intrauterine volumes were also determined for five cases of intrauterine growth retardation. Although there is some error in the serial area-volume method, the initial evaluation of five cases with intrauterine growth retardation suggests a greater precision and accuracy than volume estimates based on prolate ellipsoid geometry. Placental volume may provide an acceptable parameter to screen for intrauterine growth retardation.