A 24-year-old G2P1 woman at 39 weeks' gestation presents with painful uterine contractions. She also complains of dark, vaginal blood mixed with some mucus. Which of the following describes the most likely etiology of her bleeding

Bloody show or loss of the cervical mucus plug is often a sign of impending labor. The sticky mucus admixed with blood can differentiate bloody show from antepaum bleeding. Placenta pre, placental abruption, and vasa pre are all associated with antepaum bleeding.