Incidence of fetal loss in infertility patients after detection of fetal heart activity with early transvaginal ultrasound.

A study was conducted to determine the incidence of fetal loss after fetal heart activity (FH) had been detected with vaginal ultrasound. One hundred sixty patients with serum beta-human chorionic gonadotropin greater than 25 mIU/mL were studied. Patients underwent serial vaginal ultrasound evaluations every one to two weeks beginning the 5th week from the last menstrual period (LMP), through 12 weeks. One hundred fourteen (71%) patients had confirmation of FH (mean days from LMP, 48.1 +/- 2.9 SD). Of these, 106 (93%) patients had normally progressing pregnancy, while 8 (7%) experienced a fetal loss in the first trimester. There were no significant differences in fetal wastage after unstimulated cycles (n = 30), clomiphene citrate cycles (n = 24), human menopausal gonadotropin (hMG) cycles (n = 27) and gonadotropin releasing hormone agonist/hMG cycles (n = 33). Although mean gestational age at which post-FH fetal loss was diagnosed was 67.2 +/- 7.2 days, only two of the losses occurred after 65 days (1.7%). The probability of a pregnancy loss after the detection of FH is approximately 7%, and fewer than 2% of pregnancies with previously documented FH may have a fetal loss after nine weeks.