Journal of Ultrasound in Medicine, Vol 6, Issue 1 23-27, Copyright © 1987 by American Institute of Ultrasound in Medicine
Distinguishing normal from abnormal gestational sac growth in early pregnancy
D. A. Nyberg, L. A. Mack, F. C. Laing and R. M. Patten
In order to evaluate normal and abnormal gestational sac development,
serial sonograms were performed in 83 women whose initial sonogram
demonstrated a gestational sac lacking a detectable embryo. Of 53 normal
gestations, the mean sac growth was 1.13 mm/day (range, 0.71-1.75). In
comparison, of 30 abnormal gestations, 24 demonstrated sac growth, and of
these, the mean growth was 0.70 mm/day (range, 0.14-1.71). Based on these
observations, we suggest that gestational sac growth of less than or equal
to 0.6 mm/day is evidence for abnormal development. Analysis of the initial
and follow-up scans for the 53 normal gestations showed that a living
embryo was always detected when the mean gestational sac was greater than
25 mm in average diameter, and a yolk sac was always seen when the mean sac
diameter was greater than 20 mm. In comparison, of 30 abnormal gestations,
six were greater than 25 mm without a detectable embryo, and four were
greater than 20 mm without a yolk sac. Recommendations for the optimal time
of a follow-up sonogram are presented based on the initial sac size.
