In the case of postpartum hemorrhage, what is the best initial step in diagnosing the underlying cause of bleeding?

In the context of postpartum hemorrhage, the best initial step in diagnosing the underlying cause of bleeding is to palpate the uterine size and firmness. This examination can quickly help assess whether the uterus is contracted properly.

If the uterus is boggy or enlarged, this indicates uterine atony, which is a common cause of early postpartum hemorrhage. Identifying uterine atony allows for immediate interventions, such as uterotonics, to be initiated to control the bleeding.

Other diagnostic steps, such as ordering a complete blood count or performing manual exploration of the uterine cavity, do not provide immediate insight into the most common cause of postpartum hemorrhage and may delay necessary treatment. Additionally, while a pelvic ultrasound can help visualize retained products of conception or other abnormalities, it is not the first step as it requires time and may not address a potentially life-threatening situation promptly. Therefore, palpating the uterus is the most critical and immediate assessment that can guide further management.