Bleeding between periods - Intermenstrual Bleeding


Intermenstrual bleedingis vaginal bleeding (other than post-coital) at any time during the menstrual cycle other than during normal menstruation.

  • Bleeding between periods (intermenstrual bleeding) may be associated with sexual intercourse - bleeding during intercourse or post coital bleeding) or may occur spontaneously. It is a frequently encountered symptom - 17% per annum 0401
  • Bleeding between periods may be in the middle of the menstrual cycle - mid cycle bleeding or mid cycle spotting.
  • Bleeding between periods is one example of gynaecological abnormal bleeding.
  • Women on the pill may experience break through bleeding. This is not strictly intermenstrual bleeding because the monthly bleeding experienced by those women taking the pill is correctly called 'withdrawal bleeding' and is not spontaneous menstruation. Usually, mid cycle bleeding amounts to no more than a little mid cycle spotting. When mid cycle bleeding is accompanied by lower abdominal or pelvic pain it is known as "Mittelschmerz".
  • Intermenstrual bleeding may amount to no more than spotting between periods or it may be heavy.
  • Bleeding between periods may be misinterpreted as irregular menstruation (irregular periods).
  • When intermenstrual bleeding is reported, care should be taken to exclude pregnancy bleeding - threatened miscarriage or ectopic pregnancy.

What causes intermenstrual bleeding?

  • Physiological (hormone fluctuations) - 1-2% spot around ovulation (mid-cycle)
  • Iatrogenic (Medically Induced):
    • Combined oral contraceptive pill
    • Progesterone-only pill
    • Contraceptive depot injections
    • Intrauterine systems - Mirena0701
    • Emergency contraception0601
    • Tamoxifen
    • Following smear or treatment to the cervix
    • Drugs altering clotting parameters e.g. anticoagulants, SSRIs, corticosteroids
    • Alternative remedies e.g. ginseng, ginkgo, and soy supplements, St Johns Wort0501

  • Vaginal causes:
  • Vaginitis (bleeding uncommon before the menopause)
  • Uterine causes:
    • Endometrial polyps
    • Fibroids
    • Adenomyosis (usually only symptomatic in later reproductive years)
    • Endometrial adenocarcinoma -

      Only 2% endometrial cancers occur before 40 years old. Risk factors include:

      • Nulliparity
      • Diabetes
      • Obesity
      • Polycystic ovary syndrome
      • Chronic anovulatory cycles
      • Use of tamoxifen for treatment of breast cancer.

  • Oestrogen-secreting ovarian cancers
  • (Very rare)

How is intermenstrual bleeding Investigated?

Although worrying for many women, bleeding between periods is relatively rarely associated with sinister conditions. However, as cervical cancer and endometrial cancers can present with intermenstrual bleeding, it is imperative that they be excluded.

  • Determine that the bleeding is from the vagina, not the rectum or in the urine. Any doubt can be eliminated by inserting a tampon which will confirm presence of blood in the vagina.
  • Pregnancy test if appropriate.
  • Abdominal examination noting the presence/absence of pelvic masses.
  • Vaginal examination (speculum and bimanual) looking for obvious genital tract pathology.


Other possible investigations include:

  • Blood tests:
    • FBC
    • Clotting
    • Thyroid function
    • Infection Screen:
    • Bacteriology Swabs
    • Chlamydia Swabs
  • Transvaginal ultrasound - Ultrasound should ideally be done immediately postmenstrually as the endometrium at its thinnest and polyps and cystic areas tend to be more obvious. An endometrial thickness of 8 mm or less is significantly less likely to be associated with a malignant pathology.0602
  • Endometrial biopsy - Endometrial biopsy may be done as a surgery or clinic-based procedure using the Pipelle device or Vabra aspirator.
  • Hysteroscopy - Hysteroscopy with biopsy is the current gold-standard for investigating the uterine cavity, allowing direct visualisation and tissue diagnosis. In many centres, it can be done as a clinic procedure.

How is intermenstrual bleeding Managed?

Management depends on the cause of the bleeding:

  • If gynaecological cancer is suspected, refer urgently for investigation. Do not wait on the results of a smear test or be deterred by a previous negative result where clinical suspicion is high.
  • Cervical erosion - ectropions:
    • May resolve if the COCP is stopped or following pregnancy
    • Can be treated conservatively
    • If treatment is desired, options include thermal cautery and diathermy, cryosurgery, laser or microwave therapy.
  • Cervical polyps:
    • Avulse and send for histology
    • They are accompanied by endometrial polyps in about 25%,0701 - further investigation (ultrasound +/- hysteroscopy), particularly in older women, can be indicated.
  • Cervicitis:
    • Antibiotics dependent on organism involved
    • Contact tracing and treatment of sexual partners
    • Electrocautery of secondarily infected Nabothian follicles in chronic cervicitis
  • Dysfunctional uterine bleeding (DUB) is the most common cause of abnormal vaginal bleeding (usually heavy periods) during a woman's reproductive years. However, it is a diagnosis of exclusion and should only be diagnosed after pregnancy, iatrogenic and systemic causes and genital tract pathology have been excluded.1 It is most common at the extremes of reproductive life, in the pubertal and perimenopausal phases and is associated with anovulatory cycles in 70% of cases and, in these cases, is caused by endometrial hyperplasia.

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