A 32-year-old primigravida at 34 weeks of gestation presents to the emergency department with sudden onset of vaginal bleeding and severe abdominal pain. On examination, she is restless, blood pressure 100/60 mmHg, heart rate 110/min, and the uterus is tender and rigid. Fetal heart rate is 80/min. Ultrasound shows a retroplacental clot measuring 4 cm with 500 mL of free fluid in the pelvis. Coagulation profile shows PT 18 sec (control 12), aPTT 45 sec (control 32), fibrinogen 150 mg/dL, and platelet count 80,000/μL. What is the most appropriate immediate next step in management?