Definition of Heavy Menstrual Bleeding
Heavy menstrual bleeding (HMB) is defined as cyclic bleeding that is heavy or prolonged, objectively measured as menstrual blood loss ≥80 mL per cycle, or clinically identified by bleeding that saturates a large pad or tampon hourly for at least 4 hours, presence of clots ≥1 inch in diameter, or "flooding" requiring pad/tampon changes more frequently than hourly. 1, 2, 3
Objective Definition
- Quantitative threshold: Menstrual blood loss of 80 mL or more per menstrual cycle is the established objective cutoff for HMB 4, 5, 3
- This measurement is typically associated with anemia (hemoglobin <10 g/dL) when sustained over multiple cycles 4
Clinical/Subjective Definition
- Patient-reported assessment: HMB is characterized as a complaint of heavy cyclical menstrual bleeding occurring over several consecutive cycles that interferes with physical, emotional, social wellbeing and quality of life 4, 5, 3
- Practical clinical indicators that predict HMB include:
Important Context
- The term "heavy menstrual bleeding" is now the preferred terminology over the older term "menorrhagia" 2, 4
- HMB affects approximately 30% of women during their reproductive years 4, 3
- Up to 90% of women with underlying bleeding disorders and approximately 70% of women on anticoagulation therapy experience HMB 2
- In approximately 50% of cases, no structural pathology is identified, suggesting abnormalities in endometrial prostaglandins or the fibrinolytic system 3
Clinical Pitfalls
- Do not dismiss subjective complaints: Even when objective measurement is not feasible, patient-reported heavy bleeding that interferes with quality of life warrants evaluation and treatment 5
- Screen for bleeding disorders: HMB with flooding, prolonged menses, or accompanied by personal/family bleeding history should prompt hematology referral, as up to 20% of women with HMB have an underlying inherited bleeding disorder 2, 5