A 25-year-old gravida 3, para 2 client gave birth to a 9-pou…

A 25-year-old gravida 3, para 2 client gave birth to a 9-pound, 7-ounce boy, 4 hours ago after augmentation of labor with oxytocin (Pitocin). She presses her call light, and asks for her nurse right away, stating ā€œI’m bleeding a lot.ā€ What is the most likely cause of postpartum hemorrhaging in this client?