Success rates and estimation of gestational age for medical abortion vary with transvaginal ultrasonographic criteria,

Objective: Our purpose was to evaluate differences in gestational age and success rates for medical abortion patients obtained by using several nomograms for mean sac diameter and embryonic pole. Study Design: A retrospective review of 1011 patients was performed; the data were from 8 published studies and private patients of the primary author (M.D.C.) who received methotrexate and misoprostol for abortion. The ultrasonographic findings at baseline examination were used to estimate gestational age according to criteria established by Hellman et al and Rossavik et al for mean sac diameter and Robinson, Hadlock et al, and Goldstein and Wolfson for the embryonic pole. The assigned gestational ages of the study population were then compared, and the success rates of treatment at various gestational ages were calculated for each of the dating criteria. Results: Outcomes on the basis of gestational age for those patients who had only a gestational sac were similar regardless of which gestational age criteria were used. The final assessment of gestational age by embryonic pole according to the criteria of Goldstein and Wolfson was significantly different from the others. Conclusions: Medical abortion outcomes will vary depending on which criteria are used for establishing gestational age by both mean sac diameter and embryonic pole. (Am J Obstet Gynecol 1999;180:35-41.)