What is the definition of abnormal uterine bleeding?

Definition of Abnormal Uterine Bleeding

Abnormal uterine bleeding (AUB) is defined as bleeding from the uterus that is abnormal in regularity, volume, frequency, or duration and occurs in the absence of pregnancy. 1

Classification System: PALM-COEIN

The International Federation of Gynecology and Obstetrics (FIGO) developed the PALM-COEIN classification system to describe uterine bleeding abnormalities in women of reproductive age 1, 2:

• Structural causes (PALM) 1, 2, 3:

  • Polyps
  • Adenomyosis
  • Leiomyoma (submucosal or other myoma)
  • Malignancy and hyperplasia

• Non-structural causes (COEIN) 1, 2, 3:

  • Coagulopathy
  • Ovulatory dysfunction
  • Endometrial (primary endometrial disorders such as molecular deficiencies in the regulation of endometrial hemostasis)
  • Iatrogenic (including exogenous gonadal steroids and intrauterine devices)
  • Not yet classified

Clinical Presentations of AUB

AUB encompasses several clinical presentations 2, 4:

• Heavy menstrual bleeding (HMB): Excessive bleeding that is cyclical and predictable
• Irregular menstrual bleeding: Unpredictable bleeding patterns
• Intermenstrual bleeding (IMB): Bleeding between regular menstrual periods

Common Causes by Age Group

• Adolescents: Primarily anovulatory cycles due to immature hypothalamic-pituitary-ovarian axis; bleeding disorders present in approximately 20% of cases 5

• Reproductive-age women 1, 4:

  • Structural causes: Polyps, adenomyosis, and leiomyomas are common
  • Non-structural causes: Ovulatory dysfunction, coagulopathies, and iatrogenic causes

• Perimenopausal women: Often due to anovulation, but structural causes must be ruled out 1

• Postmenopausal women: Endometrial cancer is the most serious etiology and is the main focus of evaluation 1

Diagnostic Approach

The evaluation of AUB typically includes 1, 3:

• Laboratory tests: Pregnancy test, thyroid-stimulating hormone, prolactin levels
• Imaging: Transvaginal ultrasound (TVUS) is the primary initial imaging modality 4
• Additional studies as indicated:
  • Saline infusion sonohysterography: More accurate for detecting endometrial polyps and submucous leiomyomas 2
  • Hysteroscopy with biopsy: Reference method for definitive diagnosis 2
  • MRI: When TVUS cannot adequately visualize the endometrium 1

Management Considerations

Management depends on the underlying etiology 1, 2:

• Medical treatments for ovulatory dysfunction:

  • Progestin-only contraception
  • Combined hormonal contraception
  • Antifibrinolytic agents
  • GnRH agonists and antagonists

• Surgical options when medical treatment fails or is contraindicated:

  • Endometrial ablation
  • Hysterectomy

Important Caveats

• AUB must be distinguished from normal physiological variations in menstrual bleeding 6
• Bleeding disorders should be excluded, especially in adolescents with heavy bleeding since menarche 5
• Endometrial sampling is necessary in patients with risk factors for endometrial cancer 1
• When TVUS cannot completely evaluate the endometrium due to patient factors (body habitus, uterine position) or pathology (leiomyomas, adenomyosis), MRI or endometrial sampling should be considered 1