[Transvaginal ultrasonographic findings and hCG levels in early intrauterine pregnancies].

The correlation of transvaginal ultrasound (TVU) findings with serial hCG determinations was evaluated during early pregnancy in 60 patients. In these patients, the time of ovulation was accurately determined by ultrasonic monitoring of follicular rupture. The results were as follows. 1) A gestational sac less than 6 mm in diameter was identified in 22 of 38 cases (57.9%) in 4 weeks gestation, and the mean number of cycle days for detection of the GS was 34.1 +/- 2.5. On the other hand, fetal heart movement was detected as early as 43.0 +/- 2.8 days from the last menstrual period. 2) A good linear relationship was found between the gestational age and size of the gestational sac and size of the fetus. 3) A gestational sac was identified in one of 10 cases (10.0%) with hCG levels below 1,000 mIU/ml (1st IRP), 5 of 6 with levels of 1,000-2,000 mIU/ml, and all 15 cases with levels above 2,000 mIU/ml. These results suggested that TVU could significantly improve the detection of gestational sacs, and result in a lower hCG threshold than previously established with transabdominal sonography. Furthermore, our findings derived from patients in which the date of ovulation could be accurately determined by ultrasound should be useful in further studies of early fetal development.