Description

• HMB is a form of abnormal uterine bleeding (AUB) and is an abnormality of the volume of menstrual blood loss; this volume as defined by clinical trials is >80 mL of blood lost per cycle.
• Clinically, menstrual blood loss is not commonly measured, and HMB is more subjectively defined as “excessive menstrual blood loss that physically, emotionally, socially, and financially affects the quality of life of women.” It is based on how this deviation from normal menstrual blood volume causes disruption of the patient’s life.
• There is a consensus to abandon the use of the term menorrhagia as it is found to be confusing.

Epidemiology

• AUB is a common complaint with a prevalence of 20–30% and is one of the leading causes of outpatient gynecological visits. About 1 in 5 women in the United States experience HMB. The prevalence varies with age and is higher in adolescence and during the 5th decade of life.
• A 2019 study of 306 women conducted in the outpatient internal medicine department of a training and research university hospital found that a prevalence of HMB in women of reproductive age was 37.9%.
• HMB is linked to decreased quality of life and increased health care costs.

Incidence
HMB can present as an acute or chronic condition.

Etiology and Pathophysiology

• Any process that interferes with normal hemostatic, endocrine, or paracrine functions of the endometrium or interferes with myometrial contractility can cause HMB.
• The pathophysiology of HMB is outlined with reference to the International Federation of Gynecology and Obstetrics (FIGO) PALM-COEIN classification system of AUB. More research needs to be done to elaborate the many causes of this condition.
• HMB can be caused by structural issues such as the PALM acronym:
  • Polyp (AUB-P)
  • Adenomyosis (AUB-A)
  • Leiomyoma (AUB-L)
  • Malignancy/hyperplasia (AUB-M)
• Excessive estrogen stimulation likely causes polyps, which are abnormal outgrowths of hypertrophied endometrial tissue. It does not demonstrate the normal cyclical changes of normal endometrium causing irregular and intermenstrual HMB.
• Adenomyosis may cause HMB by affecting normal myometrial contraction, but the exact cause is unknown.
• Leiomyomas are common benign myometrial neoplasms thought to form as a result of chromosomal abnormalities and grow in response to estrogen and progesterone. The exact cause for HMB lacks sufficient evidence to support the many proposed theories.
• Excess estrogen can promote endometrial hyperplasia.
• It can also be caused by nonstructural causes which include COEIN acronym:
  • Coagulopathy (AUB-C)
  • Ovulatory (AUB-O)
  • Endometrial (AUB-E)
  • Iatrogenic (AUB-I)
  • Not yet classified (AUB-N)
• Ovulatory dysfunction is associated with a thick stratum functionalis caused by excessive estrogen stimulation of the endometrium. Endometrial shedding tends to be noncyclical with irregular bleeding noted.
• HMB can also be classified as ovulatory or anovulatory bleeding.

Genetics


Pediatric Considerations
Due to immaturity of the hypothalamic-pituitary-ovarian axis, adolescents are at risk of irregular and HMB. Of note, adolescents with heavy bleeding should be evaluated for possible bleeding disorders, especially von Willebrand disease and qualitative platelet dysfunction.

Risk Factors

Obesity

General Prevention

• Combined oral contraceptives may prevent HMB particularly when progesterone is dominant. Lower estrogen doses result in less menstrual bleeding.
• Progesterone-only contraceptives may reduce overall blood loss but often result in irregular bleeding.