Menorrhagia is the medical name given to unusually long or heavy periods. Menorrhagia may be caused by a disruption in the regulation of the menstrual cycle by hormones, disorders that affect the endometrial womb lining and abnormalities affecting the blood clotting process. In some cases menorrhagia is linked to abnormally painful periods, a condition known as dysmenorrhoea.


The menstrual cycle usually lasts between 21 and 35 days, and most women experience around 7 days of bleeding and blood loss of between 25 and 80ml. If blood loss is greater than 80ml or periods last for more than 7 days, this can be classed as menorrhagia. Menorrhagia occurs at regular intervals and can therefore be distinguished from hypermenorrhea, as this occurs on an irregular, unpredictable basis.


Heavy periods often cause distress and inconvenience in social situations, but they can also have an impact on physical health. Abnormal blood loss may exceed the body’s iron reserves, which may contribute to anaemia. Symptoms of anaemia include weakness, tiredness, lethargy, feeling the cold, numbness and tingling in the toes and fingers, a lack of concentration and headaches.


It is not common for a causative abnormality to be recognised, and the treatment used is designed to ease symptoms rather than address a specific mechanism. Possible causes include:

Coagulation (clotting) disorders

The coagulation process is involved in limiting bleeding when the endometrial womb lining breaks down and eventually stems the bleeding at the end of a period. If the clotting process is affected it may not work properly and bleeding may continue. Platelet disorders, taking anticoagulant medication (e.g. warfarin) and coagulant disorders (e.g. von willebrand disease) can cause heavy periods, although they are rare.

Excessive endometrial lining build-up

It is common for periods to be heavy before the start of the menopause, after the start of periods in young girls and the womb lining will thicken during pregnancy as a result of hormonal changes in the body. A spontaneous miscarriage may also be mistaken for an abnormally heavy period.

Hormonal disorders make up many cases of heavy periods and disorders that affect the ovaries, pituitary gland and the hypothalamus (this is known as the ovarian endocrine axis) are usually involved. Hormonal treatments can usually regulate hormone activity effectively.

If the endometrium is irritated this may cause an increase in blood loss, which may be a result of infection such as chronic or acute pelvic inflammatory disease or using the contraceptive intrauterine device.

In some cases, fibroids can cause excessive bleeding if they obtrude into the uterine cavity, as they increase the surface area of the endometrium.

Abnormalities affecting the endometrium, including adenomyosis which is known as internal endometriosis, may cause increased bleeding. True endometriosis may cause pain, but should not increase blood loss.

Endometrial cancer often causes abnormal bleeding, instead of the cyclical irregular bleeding associated with menorrhagia. Bleeding between periods and bleeding after the menopause should always be investigated.

Consideration of the menstrual cycle

Disproportionate menstrual bleeding but a regular cycle may indicate:

  • Fibroids (painless)
  • Ovarian endocrine disorder (painless)
  • Coagulation defects (this is rare and painless)
  • Pelvic inflammatory disease (painful)
  • Endometriosis (painful)

Short menstrual cycle but normal bleeding (known as polymenorrhea) may indicate:

  • Hormonal disorders

Short menstrual cycle with excessive bleeding (known as epimenorrhagia) may indicate:

  • Problems with the function of the ovaries, which may be caused by a blockage of the blood vessels associated with tumours.

Excessive bleeding and long intervals may indicate:

  • Anovular ovarian disorder caused by prolonged production of oestrogen, which could be linked with taking the oral contraceptive pill on a continuous basis (running several packs together without a break).

Differential diagnosis:

  • Pregnancy complications, which may include miscarriage, ectopic pregnancy or incomplete or threatened abortion.
  • Non-uterine bleeding, which may be caused by vaginal or cervical trauma, foreign bodies, cervical erosion, atrophic vaginitis and condylomata.
  • Pelvic inflammatory disease (known as PID).
  • Endometriosis
  • Tuberculosis

Risk factors

Risk factors for heavy periods include:

  • Obesity
  • Anovulation (not ovulating)
  • Oestrogen administration
  • Previous treatment with oral contraceptive or progestational agents (these increase the risk of atrophy of the endometrial lining, but decrease the chance of endometrial hyperplasia).


Tests and investigations that may be carried out include:

  • Rectal and pelvic examination
  • Hysteroscopy
  • Pelvic ultrasound
  • Biopsy of the endometrium (this is used to rule out endometrial cancer and atypical hyperplasia).


In cases where a fundamental cause can be acknowledged, treatment will be administered to treat the cause and likely ease the symptoms. When bleeding is abnormally heavy towards the beginning and end of the cycle (when a girl first starts her period and just before the menopause), no treatment is usually required and bleeding returns to normal spontaneously.

If anaemia occurs as a result of increased blood loss, iron tablets and increasing the amount of iron in the diet may help to ease symptoms such as tiredness and general weakness. Treatment may be advised for a set period of time if an individual develops anaemia and may be long-term.

If bleeding is mild, tests can be used in order to rule out potentially harmful causes and provide the patient with peace of mind that their condition is not associated with anything sinister or dangerous.

Menorrhagia is often treated with hormones, especially as abnormal bleeding usually occurs at the beginning and end of the menstrual years when contraception is commonly used. Oral contraceptives can be used for a short period of time, or alternatively, long-term treatment including injections of Depo Provera or the progesterone-releasing Intrauterine System. Fibroids can react to hormonal treatment, but if this is not the case and they are causing problems, they may be removed surgically.

Anti-inflammatory medication may be used, but it tends to be more effective in treating pain rather than increased blood loss. Alternative medication known as Tranexamic acid can reduce blood loss by up to 50 percent, which may be merged with hormonal therapy.

A hysterectomy is a definitive treatment for heavy periods. However, this is usually considered as a last resort, particularly for women who want to have children in the future. The risks of a hysterectomy have decreased over time thanks to advances in science and technology, but the procedure does still carry risks. Alternative surgical and non-surgical treatments may be trialled first, including endometrial ablation and the Intrauterine System.
In the UK the number of hysterectomies carried out to treat menorrhagia fell by almost half between 1989 and 2003.

Treatment options

Heavy bleeding during pregnancy requires care from a specialist gynaecological team.
A blood transfusion may be needed in cases where blood loss is caused by decreased haemodynamic stability. Treatments include:

Pharmaceutical treatments:

  • Intrauterine System insertion (first line)
  • Tranexamic acid (second line)
  • Non-steroidal anti-inflammatory medication (second line)
  • Combined oral contraceptives (second line)
  • Oral progestogen (third line)
  • Gonadotropin releasing hormone agonists

Radiological and surgical treatments:

  • Endometrial ablation
  • Hysterectomy
  • Hysteroscopic myomectomy (to extract larger fibroids)
  • Uterine artery embolisation

Note: dilation and curettage is not carried out for cases of menorrhagia.

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