The discriminatory human chorionic gonadotropin zone for endovaginal sonography: a prospective, randomized study

Area of Science:

• Reproductive Endocrinology
• Diagnostic Imaging

Background:

• Early detection of intrauterine pregnancy is crucial for management.
• Vaginal ultrasound and serum human chorionic gonadotropin (hCG) levels are commonly used for early pregnancy assessment.
• Differentiating normal intrauterine pregnancies from ectopic pregnancies relies on accurate interpretation of these markers.

Purpose of the Study:

• To determine the probability of detecting the gestational sac of a normal intrauterine pregnancy using vaginal ultrasound.
• To compare the efficacy of gestational age versus serum hCG concentration in predicting gestational sac detectability.

Main Methods:

• A prospective, randomized study involving pregnant women.
• Vaginal ultrasound and serum hCG measurements were performed between 20 and 30 days post-conception.
• Gestational sac detection was the primary outcome measure.

Main Results:

• The probability of detecting a gestational sac significantly increased with both gestational age and serum hCG concentration.
• Gestational age provided a better fit to the data than hCG concentration.
• Detection rates were similar for singleton and multiple pregnancies at the same gestational age, but lower for multiples at the same hCG concentration.

Conclusions:

• Gestational age is a more reliable parameter than serum hCG for determining expected gestational sac visibility on vaginal ultrasound.
• Failure to visualize a gestational sac by 24 days post-conception suggests a possible ectopic pregnancy.
• Relying solely on hCG levels may lead to misdiagnosis of ectopic pregnancy in cases of multiple gestations.