Use of ultrasonography vs clinical factors to estimate date of confinement.

Controversy exists regarding the use of routine ultrasound for dating of intrauterine pregnancy. This retrospective study was designed to determine the frequency of ultrasonography use and its correlation with an easily obtainable clinical date. Two hundred sixteen patients from the St. Joseph Hospital family practice residency model office over the last four years were selected for retrospective study. Criteria included single intrauterine pregnancy, birth weight of 2,500 g or greater, and spontaneous onset of labor. Data reviewed included timing, reasons, and number of ultrasonograms; reliable last menstrual periods; and compilation of clinical factors that included fundus at umbilicus, serial fundal heights, and last menstrual period. Comparison of these various clinical criteria with ultrasonogram dating showed a high correlation of last menstrual periods, clinical scores, and ultrasonograms. Many of the ultrasound studies seem to be redundant and may not have been required.