Threatened Abortion

Clinical Classification

Viable intrauterine pregnancy confirmed by ultrasound showing fetal cardiac activity at 7 weeks gestation, with a closed cervix and mild vaginal bleeding, is a key distinguishing feature of threatened abortion, according to the American College of Radiology 1, 2
Closed cervix on examination indicates the pregnancy has not progressed to inevitable abortion, as stated by the American College of Radiology 1
Mild vaginal bleeding without passage of tissue is a characteristic of threatened abortion, as noted by the American College of Radiology 1, 2

Bleeding in the first trimester occurs in 7-27% of pregnancies, with an overall miscarriage risk of approximately 12%, as reported by the American College of Radiology 1, 2
The presence of fetal cardiac activity is a reassuring prognostic sign, improving the prognosis significantly, according to the American College of Radiology 1, 2

The American College of Radiology recommends transvaginal ultrasound as the primary diagnostic tool for first trimester vaginal bleeding 1, 3, 4
Schedule follow-up ultrasound in 1-2 weeks to confirm continued viability and appropriate growth, as recommended by the American College of Radiology 3, 4
Assess for subchorionic hematoma on the ultrasound images, as this is a common associated finding, according to the American College of Radiology 1, 3

Incomplete abortion is excluded because there is a confirmed viable intrauterine pregnancy, whereas incomplete abortion involves partial passage of products of conception with retained tissue, as stated by the American College of Emergency Physicians 5

The American College of Obstetricians and Gynecologists recommends counseling the patient that first trimester bleeding increases risk of preterm delivery, placental abruption, and small for gestational age infants if the pregnancy continues, although no specific citation is provided in the text, the fact is associated with 5

The American College of Obstetricians and Gynecologists recommends measuring crown-rump length to ensure appropriate growth since the prior scan, and excluding early pregnancy loss using established criteria, such as embryonic CRL ≥7 mm without cardiac activity, which would be diagnostic of loss 6

Transvaginal ultrasound should be used to confirm continued fetal cardiac activity and viability, assess for subchorionic hematoma, and measure crown-rump length, according to the American Institute of Ultrasound in Medicine 6