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Abnormal uterine bleeding is a common presenting problem in general practice

  • Accounts for about 4% of presentations to general practice
  • 20% of women complain of heavy period bleeding – however about 50% of these have a normal amount of blood loss when investigated – perception is not reliable
  • Heavy menstrual bleeding is the most common cause of iron deficiency in the developed world
  • Don’t forget about possible pregnancy and its complications when presented with a patient with abnormal uterine bleeding!
  • Non-menstrual bleeding (postcoital, intermenstrual and postmenopausal) always warrant further investigation and consider early referral to gynaecology

In this article we discuss a brief overview of abnormal uterine bleeding. Individual types of abnormal uterine bleeding are discussed separately.

Types of abnormal uterine bleeding 

The normal cycle

  • 30-40mls average blood loss per cycle
  • <80mls is considered “normal”
  • >80mls is considered menorrhagia / heavy menstrual bleeding (HMB)
  • The two most common causes of HMB are fibroids and adenomyosis
  • Many drugs can alter menstrual bleeding, including steroids, anticoagulants and cannabis
  • Keeping a menstrual diary can be a good way to estimate blood loss – there are now lots of apps that can help to record this data

Defining normal

  • Menarche usually occurs between the ages of 10-16 (mean age 13)
    • Periods can be irregular for up to three years after menarche
    • Irregular periods after this time is considered abnormal
  • Normal range of cycle – 21-35 days
    • Mean 26-28 days
  • Menstrual flow – 2-7 days
    • Mean 3-4 days
  • Normal blood loss 20-80ml
    • Mean 30-40mls
  • Estimating volume – any flow such that menstrual pads are not able to absorb the flow is considered abnormal
  • Normal endometrial thickness – 6-12mm
  • Anovulatory cycle – defined as serum progesterone >20nmol/L in the mid-luteal phase (5-10 days before menses)
  • Abnormal uterine bleeding is more common at the extremes of reproductive age. Cancer is a more likely cause in women at the upper end of the range, and is less than 1 in 100 000 in women under 35

Dysfunctional Uterine Bleeding (DUB)

  • Defined as excessive uterine bleeding for which no organic cause can be identified.
  • Diagnosis of exclusion
  • Common – 10-20% of women will suffer it at some stage
  • Usually ovulatory rather than anovulatory
  • Common in late 30s and early 40s
  • Up to 40% of patients initially diagnosed as DUB will ultimately have fibroids, endometrial polyps or some other organic cause later identified


  • Heavy bleeding, saturated pads, “accidents”, “flooding” clots
  • Prolonged bleeding
    • Menstruation >7 days, OR
    • Heavy bleeding > 4 days
  • Frequent bleeding – more often than every 21 days
  • Usually do not have pelvic pain or tenderness


As for heavy menstrual bleeding


  • Menstrual calendar
  • Ensure no iron deficiency anaemia
  • Reassurance about the absence of identified pathology
  • Consider drug therapy
    • First line are antiprostaglandins – NSAIDs and tranexamic or mefanamic acid. Start as soon as bleeding starts and continue for 5 days. Between 60-80% of patients can control symptoms with one of these agents alone
    • Contraceptive pill is second line – about 80% of patients will respond to COC
    • Hormonal IUD (Mirena) is the most effective hormonal agent – reduces bleeding by 95%
    • Progesterone reduced bleeding by 85% – although pill preparations usually much less effective. Depo-provera will induce amenorrhoea in about 50% of patients within 1 year
    • COC reduces bleeding by 50%
    • Tranexamic acid reduces bleeding by 40%
    • NSAIDs reduce bleeding by 30%
  • In extreme cases – consider surgical management if medical management is unsuccessful and fertility is no longer desirable
    • Endometrial ablations
    • Hysterectomy
    • Tranexamic acid 1-1.5g PO TDS until bleeding stops


Irregular menstrual cycle

  • Usually hormonal in origin
  • Only rarely is there an organic cause in patients under 35
    • Consider PCOS – particularly if there are any other features present
  • COC or POP often used to treat symptomatically
  • Patients over 35 need thorough investigation for an organic cause – usually endometrial biopsy +/- hysteroscopy


  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.

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