Evaluation and differential diagnosis of vaginal bleeding before 20 weeks of gestation in hemodynamically stable patients

hCG: human chorionic gonadotropin.

* In the early first trimester when cardiac activity is not normally seen by ultrasound, diagnosis of a nonviable embryo is based on factors such as the mean gestational sac diameter and crown-rump length. Refer to UpToDate topics on ultrasound diagnosis of pregnancy loss. Repeat ultrasound in 7 to 10 days may be required to make a diagnosis of viable versus nonviable pregnancy.

¶ Evaluation for ectopic pregnancy involves a combination of serial hCG levels and ultrasound examinations. Refer to the UpToDate topic on diagnosis of ectopic pregnancy for detailed information.

Δ If there is no intrauterine pregnancy on ultrasound but the uterus is not empty, then gestational trophoblastic disease should be considered if ultrasound shows a central intrauterine heterogeneous mass. Refer to UpToDate topics on gestational trophoblastic disease for detailed information.

◊ Implantation bleeding is a diagnosis of exclusion. It is characterized by a small amount of spotting or bleeding approximately 10 to 14 days after fertilization (around the time of the missed menstrual period).