Predicting pregnancy outcome by the observation of a gestational sac or of early fetal cardiac motion with transvaginal ultrasonography.

Transvaginal ultrasound (US) allows for observation of the gestational sac and cardiac motion as early as 3 and 4 weeks after ovulation, respectively. The purpose of this study was to determine how well the first observation of cardiac motion, using weekly transvaginal US examinations, predicted pregnancy outcome. Three hundred sixteen pregnancies wherein the date of ovulation was known and a single gestational sac was visualized at 3 weeks after ovulation were studied. Cardiac motion was first detected at 4 weeks after ovulation in 226 (71.5%), and at 5 weeks in 67 (21.2%). In 23 patients, cardiac motion was never observed. In those patients with cardiac motion visible at 4 weeks after ovulation, 94.2% have subsequently delivered viable infants. This contrasts with only 70.1% for those patients who first had observable cardiac motion 1 week later (P = 6.7 X 10(-6]. This study demonstrates that the solo finding of a gestational sac is a poor predictor of pregnancy outcome (82.3% accurate) and that the earlier that cardiac motion is initially observed, the better the pregnancy prognosis.