Operational Definition of Abnormal Uterine Bleeding (AUB)
Abnormal uterine bleeding is defined as bleeding from the uterine corpus that is abnormal in regularity, volume, frequency, or duration occurring in the absence of pregnancy in women of reproductive age. 1
Core Parameters
The International Federation of Gynecology and Obstetrics (FIGO) established standardized definitions based on 5th to 95th percentile data from large epidemiologic studies, defining normal versus abnormal bleeding patterns: 2
- Regularity: Deviations from predictable cyclical patterns 1
- Volume: Excessive blood loss during menstruation 1
- Frequency: Bleeding episodes occurring too frequently or infrequently 1
- Duration: Menstrual periods lasting longer than normal parameters or bleeding occurring between cycles 1
Clinical Categories
AUB encompasses two main bleeding patterns: 1
- Heavy Menstrual Bleeding (HMB): Predictable cyclical bleeding that is excessive in volume or duration (exceeding 8 days), most commonly caused by fibroids, adenomyosis, copper IUD, or coagulation disorders 1, 3
- Intermenstrual Bleeding (IMB): Irregular non-cyclical bleeding between menstrual periods, commonly caused by ovulatory dysfunction (polycystic ovaries), endometrial polyps, or IUD 1
Important Terminology Updates
The term AUB replaces outdated and ambiguous terminology including "dysfunctional uterine bleeding," "irregular menstrual bleeding," and "menorrhagia," which had conflicting definitions. 4, 3 This standardization improves communication among clinicians, educators, and researchers worldwide. 2
Duration Requirement
AUB must persist for at least 6 months to meet the operational definition, distinguishing it from transient bleeding variations. 2
Critical Exclusion
The definition explicitly requires the absence of pregnancy, as this fundamentally changes the diagnostic and management approach. 1