Postpartum Hemorrhage Definitions and Management

Diagnostic Criteria

• The American College of Obstetricians and Gynecologists defines postpartum hemorrhage as blood loss ≥500 mL after vaginal delivery or ≥1000 mL after cesarean section, with severe PPH defined as blood loss ≥1000 mL regardless of delivery route 1, 2
• The threshold for significant blood loss varies by delivery route and severity, with vaginal delivery triggering immediate clinical response at >500 mL and cesarean section at >1000 mL 1, 2

Clinical Action Thresholds

• Immediate actions must be initiated as soon as abnormal bleeding is recognized, including blood sampling for complete blood count, coagulation studies, group and screen, and venous blood gas for rapid hemoglobin and lactate measurement 1, 2
• Severe PPH occurs in approximately 2% of deliveries in developed countries and requires immediate tranexamic acid administration 3

Blood Loss Severity Stratification

• Blood loss of 500-1000 mL is associated with an increased risk of progression to severe hemorrhage, particularly when spontaneous placental delivery is delayed >30 minutes (RR 5.94) 3, 4
• Blood loss >1000 mL is considered severe PPH and requires aggressive intervention 3

Measurement and Assessment

• Visual estimation of blood loss is notoriously inaccurate and systematically underestimates actual hemorrhage, while direct measurement using collection bags or weighing blood-soaked materials correlates better with hemoglobin drop and improves outcomes 1, 2