Abnormal uterine bleeding (AUB) is a broad term for irregularities in the menstrual cycle. Approximately one-third of women will experience abnormal bleeding in their lifetime.
Terms previously used to describe variations in the frequency and length, as well as the amount of blood lost during the menstrual cycle, include menorrhagia and dysfunctional uterine bleeding. In 2011, the International Federation of Gynecology and Obstetrics (FIGO) updated the terminology for abnormal uterine bleeding. The FIGO guidelines redefine AUB and its common causes.
Why FIGO Reclassified the Causes of AUB
Before FIGO's reclassification of AUB causes, the different terms were inconsistently applied and lacked standardized categorization. This variation made it difficult for investigators to study homogeneous populations experiencing AUB and compare studies. Agreeing upon one system of nomenclature and classification would make research and evidence-based management and treatment easier. However, creating a coherent classification system is challenging because AUB is often asymptomatic, and a woman can have several symptoms at once.
FIGO was previously successful in creating a universally accepted staging system for cancer of the genital tract. Still, results have been mixed for other gynecological conditions, such as endometriosis and pelvic organ prolapse. To develop a standardized classification system for AUB, a group of panellists—consisting of gynecologists, reproductive endocrinologists, and other clinicians and researchers—independently rated a series of symptoms on a numerical scale. These were re-rated after discussion and modified until the panellists developed a draft system. After minor revisions, the system was presented to over 700 attendees at the 2009 FIGO World Congress in Cape Town, South Africa.
Results of the FIGO Rating Process
The initial panel agreed that AUB wasn't restricted to abnormally heavy menstrual bleeding but also to bleeding that was abnormal in timing. The group also decided that the term "dysfunctional uterine bleeding" (DUB) should be discarded. DUB was used as a gynecological diagnosis when there was no systemic or locally definable structural cause for AUB.
At the Cape Town Congress, 90.7 percent of respondents agreed that AUB was sufficient for describing disturbed menstrual bleeding. Respectively, 68.1 percent and 76.7 percent agreed that menorrhagia and DUB should be discarded, with 83.5 percent agreeing that heavy menstrual bleeding should replace menorrhagia.
Categories of the FIGO Classifications
Based on group recommendations, FIGO developed categories arranged by the acronym PALM-COEIN:
- Polyp (AUB-P). Polyps are categorized as either present or absent
- Adenomyosis (AUB-A). Tissue that normally lines the endometrial tissue has grown into the uterine wall
- Leiomyoma (AUB-L). Many leiomyomas, frequently known as fibroids, are asymptomatic and do not always cause AUB; the new system reflects only the presence of one or more leiomyomas, and depending on the site, leiomyomas may be further subdivided into submucosal or other, which can then be further divided into nine tertiary categories from the Wamsteker classification
- Malignancy and hyperplasia (AUB-M). Although they are uncommon, malignancies and hyperplasia are important causes of AUB and must be considered in all women of reproductive age
- Coagulopathy (AUB-C). AUB may be related to several underlying conditions that cause heavy menstrual bleeding
- Ovulatory dysfunction (AUB-O). Irregular bleeding patterns related to disorders that affect ovulation and hormonal dysregulation
- Endometrial (AUB-E). AUB that occurs within the context of predictable menstrual bleeding, with no other definable cause, and is most likely related to an endometrial disorder
- Iatrogenic (AUB-I). AUB caused by medical interventions or devices, such as intrauterine systems
- Not yet classified (AUB-N). This categorization applies to cases where a specific entity for AUB cannot be determined
The categories in the PALM group are structural and clinicians can measure them visually with imaging techniques. Categories in the COEIN group are non-structural and cannot be defined by imaging or histopathology.
The new classifications recognize that a patient may have one or more entities that cause or contribute to AUB, and certain entities may be asymptomatic. Because of this, FIGO has designed the system to enable categorization and notation that allow for multiple causes. The system follows the World Health Organization (WHO) tumor, node, and metastasis (TNM) staging of malignant tumors for notation.
2018 Modifications to FIGO Classifications
In 2018, the International Federation of Gynecology and Obstetrics (FIGO) revised its system for AUB. This updated system moved AUB secondary to anticoagulants from the coagulopathy category to the iatrogenic category. Conditions excluded from the not yet classified category include pelvic inflammatory disease, chronic liver disease, and cervicitis.
Both the 2011 and 2018 FIGO classifications play a pivotal role in the investigation and management of AUB in women of reproductive age. The nature of the classifications enables a standardized approach to gynecological diagnosis to ensure optimal patient care.
