Objective: The aims of our study were to evaluate historical and sonographic factors that might contribute to the miscarriage rate associated with a small first-trimester gestational sac; and to determine the outcome in those pregnancies with a small gestational sac who do not miscarry.
Methods: 190 patients with a small gestational sac between 5.7 and 9.0 weeks’ gestation, defined as the mean sac diameter minus the embryonic size < 5.0 mm, were followed prospectively. A control group consisted of 155 patients with a normal gestational sac diameter between the same gestational ages. Pregnancies that did not miscarry were followed until delivery.
Results: The spontanenous abortion rate for those pregnancies between 5.7–9.0 weeks’ gestation with a small gestational sac (108/190; 57.0%) was significantly higher than for the control group (10/155; 6.5%) (p<0.01). A multivariate analysis among women with a mean sac minus embryonic size < 5.0 mm evaluated maternal age > 35 years, first-trimester vaginal bleeding, mean sac diameter minus embryonic size < 3.0 mm, and a small embryonic size for gestational age for their effect upon the miscarriage rate. First-trimester vaginal bleeding and small embryonic size for gestational age proved to be significant. When compared to controls, women with a small gestational sac were more likely to deliver prematurely and deliver a child of low birth weight.
Conclusions: The prediction of miscarriage from a small gestational sac between 5.7–9.0 weeks’ gestation is, at best, fair (miscarriage rate: 57.0%). If the pregnancy continues, the neonate is more likely to deliver prematurely and therefore, have a lower birth weight.
© 2003 Published by Elsevier Inc.