Heavy menstrual bleeding (HMB)

Menorrhagia (heavy menstrual bleeding) is defined as regular, excessive menses occurring over several consecutive cycles in an otherwise normal menstrual cycle (1).

• it is largely a subjective definition as what constitutes heavy bleeding to one woman may be quite normal for another
• can be associated with both ovulatory and anovulatory ovarian cycles (2)

NICE suggest that for clinical purposes, heavy menstrual bleeding (HMB) should be defined as excessive menstrual blood loss which interferes with the woman's physical, emotional, social and material quality of life, and which can occur alone or in combination with other symptoms. Any interventions should aim to improve quality of life measures (1).

• HMB is one of the most common reasons for gynaecological consultations in both primary and secondary care (1)
  • about 1 in 20 women aged between 30 and 49 years consult their GP each year because of heavy periods or menstrual problems, and menstrual disorders comprise 12% of all referrals to gynaecology services

Older texts would define menorrhagia when menses associated with:

• clots
• the use of towels rather than tampons
• flooding
• associated dysmenorrhoea

Objectively, menorrhagia has been defined as blood loss more than 80 mL in an otherwise normal menstrual cycle (1) (average blood loss is 30 - 40 ml per cycle) (2).

• this value was chosen since it appears to be the maximum amount that a woman on a normal diet can lose per cycle without becoming iron deficient
• according to population studies only 10% of the women had blood loss of less than 80 ml, although almost one third of women considered their menstruation to be excessive (2)
• in practice, actual blood loss is rarely measured.

NICE suggest that if the woman has a history of HMB without other related symptoms (such as persistent intermenstrual bleeding, pelvic pain and/or pressure symptoms, that might suggest uterine cavity abnormality, histological abnormality, adenomyosis or fibroid) (1):

• then consider pharmacological treatment without carrying out a physical examination (unless the treatment chosen is levonorgestrel-releasing intrauterine system [LNG IUS])

Also consider starting pharmacological treatment for HMB without investigating the cause if the woman's history and/or examination suggests a low risk of fibroids, uterine cavity abnormality, histological abnormality or adenomyosis (1).

References:

1. Heavy menstrual bleeding: assessment and management. NG88. NICE Guideline (March 2018 - updated May 2021)
2. Munro MG, Critchley HOD, Broder MS, et al. FIGO classification system (PALM-COEIN) for causes of abnormal uterine bleeding in nongravid women of reproductive age. Int J Gynaecol Obstet. 2011 Apr;113(1):3-13.