Abnormal Uterine Bleeding

Abnormal uterine bleeding (AUB) is uterine bleeding that is abnormal in frequency, regularity, duration, or volume in non-pregnant women of reproductive age. It is one of the most common gynecologic complaints and is now organized by the FIGO PALM-COEIN system, which groups its causes into structural and non-structural categories.

Definition

Abnormal uterine bleeding is uterine bleeding from the corpus or cervix that is abnormal in frequency, regularity, duration, or volume in a non-pregnant woman of reproductive age, classified by the FIGO PALM-COEIN system according to its underlying cause.

Scope

This entry covers abnormal uterine bleeding as a clinical entity and, in particular, the standardized FIGO framework used to describe and classify it. It explains the PALM-COEIN structure and how it separates structural from non-structural causes, and it relates AUB to the other benign gynecologic conditions that frequently produce it. It is a reference overview and does not provide treatment recommendations.

Core questions

• What counts as abnormal uterine bleeding in terms of frequency, regularity, duration, and volume?
• How does the FIGO PALM-COEIN system organize the causes of AUB into structural and non-structural categories?
• Why did standardized FIGO terminology replace older, ambiguous terms such as 'menorrhagia' and 'dysfunctional uterine bleeding'?

Key concepts

• Bleeding abnormal in frequency, regularity, duration, or volume
• FIGO PALM-COEIN classification
• Structural causes: Polyp, Adenomyosis, Leiomyoma, Malignancy and hyperplasia
• Non-structural causes: Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not otherwise classified
• Heavy menstrual bleeding
• Standardized terminology replacing 'menorrhagia' and 'dysfunctional uterine bleeding'

Mechanisms

Abnormal uterine bleeding is a symptom with many possible causes rather than a single disease, and the FIGO PALM-COEIN system groups these causes systematically. The structural ('PALM') categories — Polyp, Adenomyosis, Leiomyoma, and Malignancy and hyperplasia — are entities definable by imaging or histopathology, whereas the non-structural ('COEIN') categories — Coagulopathy, Ovulatory dysfunction, Endometrial disorders, Iatrogenic causes, and Not otherwise classified — are not. Bleeding can result from disrupted uterine anatomy, disordered ovulation and the resulting hormonal effects on the endometrium, disturbances of hemostasis, or external factors, and more than one category may contribute in a given patient.

Clinical relevance

Abnormal uterine bleeding is among the most frequent reasons women seek gynecologic care and is a common pathway to investigation of conditions such as fibroids, adenomyosis, polyps, and ovulatory dysfunction. The PALM-COEIN framework supports consistent description and comparison across research and clinical settings. This entry describes the symptom and its classification for reference purposes and is not a basis for individual diagnostic or treatment decisions.

Epidemiology

Abnormal uterine bleeding, including heavy menstrual bleeding, is a very common gynecologic complaint among women of reproductive age and a frequent reason for consultation and investigation. Its causes are distributed across the PALM-COEIN categories, with structural lesions such as fibroids contributing to a substantial share of cases; precise frequencies vary with population and diagnostic approach.

History

Historically, uterine bleeding was described with inconsistent and overlapping terms such as 'menorrhagia,' 'metrorrhagia,' and 'dysfunctional uterine bleeding,' which hampered research and communication. In 2011 FIGO introduced standardized terminology and the PALM-COEIN classification of causes, revised in 2018, providing a common framework that distinguishes structural from non-structural causes and that has been widely adopted.

Key figures

• Malcolm G. Munro
• Hilary O. D. Critchley
• Ian S. Fraser

Seminal works

• munro-2018

Frequently asked questions

What does PALM-COEIN stand for?

It is the FIGO classification of causes of abnormal uterine bleeding. PALM covers structural causes — Polyp, Adenomyosis, Leiomyoma, and Malignancy and hyperplasia — and COEIN covers non-structural causes — Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, and Not otherwise classified.

Why are older terms like 'menorrhagia' being replaced?

Terms such as 'menorrhagia' and 'dysfunctional uterine bleeding' were used inconsistently and lacked precise meaning. FIGO introduced standardized terminology and the PALM-COEIN system so that bleeding patterns and their causes are described uniformly across research and practice.