Postpartum hemorrhage (PPH) is an obstetrical emergency that can follow vaginal or cesarean delivery. It is a major cause of maternal morbidity, and one of the top three causes of maternal mortality in both high and low per capita income countries, although the absolute risk of death from PPH is much lower in high income countries (1 in 100,000 deliveries in the United Kingdom versus 1 in 1000 deliveries in the developing world). Hemorrhage is the most common reason postpartum women are admitted to intensive care units and arguably the most preventable cause of maternal mortality. Timely, accurate diagnosis is important to initiate appropriate interventions (eg, drugs, surgery, referral) and improve outcome .
The incidence of postpartum hemorrhage varies widely, depending upon criteria used to define the disorder. A reasonable estimate is 1 to 5 percent of deliveries . In an analysis of population-based data from the United States National Inpatient Sample for the years 1994-2006, the discharge diagnosis of PPH increased 26 percent over this period (from 2.3 to 2.9 percent) . Uterine atony was the most common cause of PPH and accounted for most of the increase. The proportion of women diagnosed with uterine atony increased from 1.6 to 2.4 percent over the 12 year period.
PPH is defined as primary or secondary: primary PPH occurs in the first 24 hours after delivery (also called early PPH) and secondary PPH occurs 24 hours to 12 weeks after delivery (also called late or delayed PPH).
PPH is best defined/diagnosed clinically as excessive bleeding that makes the patient symptomatic (eg, pallor, lightheadedness, weakness, palpitations, diaphoresis, restlessness, confusion, air hunger, syncope) and/or results in signs of hypovolemia (eg, hypotension, tachycardia, oliguria, oxygen saturation <95 percent) (table 1). Heavy vaginal bleeding is usually noted, but vaginal bleeding may not be abnormal when hemorrhage is internal, for example, intraabdominal bleeding related to a cesarean delivery or a broad ligament or vaginal hematoma due to a sulcus laceration.
Other definitions for PPH that have been proposed have been problematic. The most common definition is estimated blood loss ≥500 mL after vaginal birth or ≥1000 mL after cesarean delivery. The inadequacy of this definition was illustrated in studies that assessed blood loss using various objective methods: the mean blood loss reported after vaginal and cesarean deliveries was approximately 400 to 600 mL and 1000 mL, respectively, and clinicians were likely to underestimate the volume of blood lost [4-6].