Postpartum hemorrhage is a life-threatening condition that is defined as blood loss of more than 500 milliliters after vaginal delivery or more than 1000 milliliters after cesarean section. It occurs in approximately 5% to 18% of births and is most likely to occur after cesarean delivery. The most common cause of postpartum hemorrhage is uterine atony.
The first indication of postpartum hemorrhage (PPH) may be blood-drenched pads and bed sheets. There may also be copious amounts of vaginal bleeding or symptoms of significant blood loss or hypovolemic shock (e.g., palpitations, dizziness, hypotension, tachycardia, weakness, pallor)  . Symptoms may onset quickly, such as in the case of uterine atony, or they may appear more gradually  . Anemia, fatigue and orthtostatic hypostension may present as complications due to PPH. Postpartum hemorrhage is also associated with increased morbidity and mortality.
The diagnosis of postpartum hemorrhage begins with recognition of excessive bleeding by either visual confirmation (e.g., copious vaginal bleeding) or recognition of symptoms associated with significant blood loss (e.g., tachycardia, pallor, fatigue, hypotension)  . Subsequent steps in the workup of postpartum hemorrhage are to determine the cause of the blood loss, amount of blood lost, and treatment.
In patients with postpartum hemorrhage, a physical exam of the lower abdomen and uterine area may reveal a uterine atony. Uterine atony is one of the most common causes of postpartum hemorrhage; it is characterized by a boggy uterus and swollen or expanded uterine size   . The patient's risk factors for uterine atony should be assessed (e.g, uterine overdistention, prolonged labor, rapid labor and delivery, chorioamnioitis, delivery of 5 or more live infants)  .
On examination, blood may be seen at the introitus if the placenta has delivered. If the placenta is retained, then blood may be retained in the uterus behind the remaining placenta and/or the membranes. Hematomas seen on the retroperitoneum or lower genital tract may also be indicative of bleeding  .
The onset of postpartum hemorrhage is rapid in most cases, with little to no time for laboratory or imaging work up. However, laboratory tests and ultrasound may aid in diagnosis and determination of an etiology.
Oba T, Hasegawa J, Sekizawa A. Postpartum ultrasound: postpartum assessment using ultrasonography.J Matern Fetal Neonatal Med. 2016;30:1-4.