Model Answer
0 min readIntroduction
Abnormal Uterine Bleeding (AUB) is a common gynecological complaint affecting women of reproductive age and perimenopausal women. Historically, the classification of AUB was complex and lacked standardization. The International Federation of Gynecology and Obstetrics (FIGO) introduced the PALM-COEIN system in 2011 to provide a unified approach. However, recognizing its limitations, FIGO revised the classification in 2018, aiming for improved clarity and clinical applicability. This revised system categorizes AUB based on structural (PALM) and non-structural (COEIN) causes, guiding diagnosis and management. Understanding the endometrial patterns associated with each category is vital for accurate diagnosis and tailored treatment.
The Revised FIGO Classification of AUB (2018)
The FIGO system classifies AUB into two main categories: PALM (Polyp, Adenomyosis, Leiomyoma, Malignancy and Hyperplasia) and COEIN (Coagulopathy, Ovulatory Dysfunction, Endometrial, Iatrogenic, Not yet classified). This system prioritizes identifying and addressing the underlying cause of bleeding.
Endometrial Patterns in Various Types of AUB
1. PALM – Structural Causes
- Polyp (AUB-P): Endometrial polyps are localized overgrowths of endometrial tissue. Histologically, they show a fibrovascular core covered by endometrial epithelium. The endometrial pattern within the polyp is often proliferative, but can also be secretory depending on the menstrual cycle phase.
- Adenomyosis (AUB-A): Characterized by endometrial tissue within the myometrium. Endometrial biopsies are often normal, but may show basal endometrial changes. The key diagnostic feature is histological evidence of endometrial glands and stroma within the myometrium, typically found on hysterectomy specimens.
- Leiomyoma (AUB-L): Uterine fibroids. The overlying endometrium is usually normal, but can exhibit proliferative changes due to hormonal stimulation. Submucosal fibroids are more likely to cause AUB due to their distortion of the endometrial cavity.
- Malignancy and Hyperplasia (AUB-M): This category encompasses endometrial cancer and endometrial hyperplasia.
- Endometrial Hyperplasia without Atypia: Characterized by increased endometrial gland density and irregularity, but without cellular atypia.
- Endometrial Hyperplasia with Atypia: Shows similar features to hyperplasia without atypia, but with cellular atypia, increasing the risk of progression to cancer.
- Endometrial Cancer: Histologically, endometrial adenocarcinoma is the most common type. Grading (G1-G3) is based on the degree of differentiation and aggressiveness.
2. COEIN – Non-Structural Causes
- Coagulopathy (AUB-C): Disorders affecting blood clotting (e.g., von Willebrand disease) can cause heavy menstrual bleeding. Endometrial biopsies are typically normal.
- Ovulatory Dysfunction (AUB-O): Irregular ovulation leads to unpredictable endometrial shedding. Endometrial biopsies may show a range of patterns, including proliferative, secretory, or disordered proliferative endometrium. Anovulatory cycles often result in prolonged exposure of the endometrium to estrogen, potentially leading to endometrial hyperplasia.
- Endometrial (AUB-E): This category includes primary endometrial dysfunction, where the endometrium itself is the source of bleeding. Histological findings can be variable, ranging from normal to chronic endometritis (inflammation of the endometrium).
- Iatrogenic (AUB-I): Bleeding caused by medical interventions (e.g., intrauterine devices, anticoagulants). Endometrial biopsies are usually normal, but may show foreign body reaction in cases of IUD-related bleeding.
- Not Yet Classified (AUB-N): This category is reserved for causes of AUB that are not yet fully understood. Endometrial patterns are highly variable and depend on the underlying cause.
Role of Endometrial Biopsy
Endometrial biopsy is crucial in evaluating AUB, particularly in women over 45 years or those with risk factors for endometrial cancer. It helps to identify endometrial hyperplasia or cancer, assess the effects of hormonal therapy, and rule out other endometrial abnormalities. The timing of the biopsy relative to the menstrual cycle can influence the findings, with biopsies ideally performed during the secretory phase to assess endometrial responsiveness to hormones.
| AUB Category | Typical Endometrial Pattern |
|---|---|
| Polyp | Proliferative or Secretory |
| Adenomyosis | Normal or Basal Endometrial Changes |
| Leiomyoma | Usually Normal, potentially Proliferative |
| Hyperplasia without Atypia | Increased Gland Density, Irregularity |
| Hyperplasia with Atypia | Increased Gland Density, Irregularity, Cellular Atypia |
| Endometrial Cancer | Adenocarcinoma (G1-G3) |
| Ovulatory Dysfunction | Proliferative, Secretory, or Disordered Proliferative |
Conclusion
The revised FIGO classification of AUB provides a standardized framework for diagnosis and management. Understanding the endometrial patterns associated with each AUB category is essential for accurate diagnosis and appropriate treatment. Endometrial biopsy remains a cornerstone of evaluation, particularly in high-risk patients. Further research is needed to refine our understanding of the non-structural causes of AUB and develop more targeted therapies. A holistic approach, considering both structural and non-structural factors, is crucial for optimal patient care.
Answer Length
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