A 32-year-old primigravida at 34 weeks of gestation presents to the emergency department with painless vaginal bleeding of 200 mL. She denies abdominal pain, contractions, or leakage of fluid. Vital signs are stable (BP 128/82, HR 88, RR 18). On speculum examination, blood is seen pooling in the vagina with no cervical source identified. Transabdominal ultrasound confirms a placenta covering the internal cervical os. What is the most appropriate immediate management?