SERIAL TRANSVAGINAL ULTRASOUND SCANS AND BETA-HUMAN CHORIONIC-GONADOTROPIN LEVELS IN EARLY SINGLETON AND MULTIPLE PREGNANCIES

Objective: To determine if serum beta-hCG levels are higher in multipl e gestations than in singleton pregnancy at the time of intrauterine s ac visualization and the first appearance of fetal heart activity as d ocumented by serial transvaginal ultrasound (US). Design: Prospective analysis of serial transvaginal US findings in 19 pregnancies correlat ed with serum hCG levels during early gestation. Setting: Reproductive endocrinology division of the University of Arkansas for Medical Scie nces, Little Rock, Arkansas. Patients: Nineteen infertility patients w ere studied after conceiving. Thirteen underwent IVF or GIFT, 4 receiv ed hMG therapy, 1 was treated with clomiphene citrate, and 1 pregnancy followed spontaneous ovulation. Interventions: Transvaginal US and hC G levels were obtained every Monday, Wednesday, and Friday from 20 to 22 days after ovulation until the appearance of fetal heart activity. Results: Initial sac visualization occurred at lower serum hCG levels in singleton versus multiple pregnancies (2,180 +/- 1,170 versus 7,028 +/- 4,280 mIU/mL, mean +/- SD). Sacs were always seen when the serum hCG level (mIU/mL) was greater-than-or-equal-to 1,161 in singleton, 1, 556 in twin, 3,372 in triplet, an 9,399 in quadruplet pregnancies. Con clusion: Failure to observe an intrauterine sac by transvaginal US in the presence of serum hCG levels in the 1,000 to 2,000 mIU/mL range is not pathognomonic for an ectopic gestation. Clinical symptomatology, risk of multiple pregnancies, and gestational age must also be conside red.