What are the causes of abnormal uterine bleeding (AUB)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Article Review Status
Submitted
Under Review
Approved

Last updated: March 5, 2025 • View editorial policy

From the Guidelines

Abnormal uterine bleeding (AUB) is primarily caused by structural and nonstructural factors, as outlined in the PALM-COEIN classification system, which includes polyp, adenomyosis, leiomyoma, malignancy and hyperplasia, coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not yet classified causes. The PALM-COEIN system, developed to describe uterine bleeding abnormalities in women of reproductive age, is a comprehensive framework for understanding the etiologies of AUB 1.

Key Causes of AUB

  • Structural causes: polyp, adenomyosis, leiomyoma (submucosal or other myoma), and malignancy and hyperplasia
  • Nonstructural causes: coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not yet classified ### Management of AUB Treatment of AUB depends on the underlying cause, and medical treatments such as progestin-only contraception and combined hormonal contraception are often used to manage AUB associated with ovulatory dysfunction 1.

Surgical Options

If medical treatment fails, is contraindicated, or is not tolerated, or if the patient has concomitant significant intracavitary lesions, surgery, including endometrial ablation and hysterectomy, may be an option 1.

Importance of Accurate Diagnosis

Accurate diagnosis of the underlying cause of AUB is crucial to guide treatment and improve patient outcomes, and the PALM-COEIN system provides a useful framework for classification and management of AUB 1.

From the FDA Drug Label

In undiagnosed persistent or recurrent abnormal bleeding from the vagina, adequate diagnostic measures are indicated to rule out pregnancy or malignancy. Non-hormonal causes should be considered and adequate diagnostic measures taken to rule out malignancy or pregnancy in the event of breakthrough bleeding, as in the case of any abnormal vaginal bleeding.

The causes of abnormal uterine bleeding (AUB) include:

  • Pregnancy
  • Malignancy
  • Non-hormonal causes These causes should be ruled out through adequate diagnostic measures in cases of undiagnosed persistent or recurrent abnormal bleeding from the vagina 2, 3.

From the Research

Causes of Abnormal Uterine Bleeding (AUB)

  • Hormonal contraception: Abnormal uterine bleeding is a common side effect of hormonal contraception, including combination oral contraceptive pills, progestin-only pills, medroxyprogesterone acetate injections, and subdermal levonorgestrel implants 4, 5.
  • Pregnancy: Pregnancy is a frequent cause of abnormal uterine bleeding, particularly if the pregnancy is unplanned or if the woman is not using hormonal contraception correctly 4.
  • Misuse of oral contraceptive pills (OCPs): Misuse of OCPs, such as missing pills or taking them incorrectly, can lead to abnormal uterine bleeding 4.
  • Structural etiologies: Structural etiologies, such as polyps, adenomyosis, leiomyoma, malignancy, and hyperplasia, can cause abnormal uterine bleeding 6.
  • Nonstructural etiologies: Nonstructural etiologies, such as coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not otherwise classified, can also cause abnormal uterine bleeding 6.
  • Dysfunctional uterine bleeding (DUB): DUB is a common cause of abnormal uterine bleeding, particularly in women with no clear etiology for their bleeding 7, 8.

Classification of AUB

  • The acronym PALM-COEIN is used to classify abnormal uterine bleeding, with PALM referring to structural etiologies and COEIN referring to nonstructural etiologies 6.

Evaluation and Treatment of AUB

  • Evaluation of abnormal uterine bleeding involves a detailed history and pelvic examination, as well as laboratory testing and imaging studies 4, 5, 6.
  • Treatment options for abnormal uterine bleeding include medical and surgical approaches, such as hormonal therapy, nonsteroidal anti-inflammatory drugs, and surgery 4, 5, 7, 8, 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.