Menorrhagia

What it is

Menorrhagia — also called heavy menstrual bleeding (HMB) — is abnormally heavy or prolonged menstrual bleeding that interferes with daily life, affecting an estimated 20–30% of women of reproductive age and standing as one of the most common gynaecological complaints seen in Canadian primary care. Clinically, menorrhagia is defined as blood loss exceeding 80 ml per cycle or bleeding lasting more than 7 days, though in practice most clinicians assess it by its impact on daily functioning rather than by measuring volume. It is a leading cause of iron deficiency anaemia and can significantly limit a person's ability to work, exercise, and participate in social activities.

Heavy menstrual bleeding is a symptom, not a standalone diagnosis. A thorough evaluation is needed to identify the underlying cause — hormonal, structural, or haematological — before treatment can be properly targeted. In Canada, initial workup is typically accessible through a family physician or nurse practitioner, with referral to gynaecology for complex or refractory cases.

Causes and mechanism

The causes of menorrhagia fall into three broad categories:

Category	Common examples	Key mechanism
Hormonal	Anovulation, estrogen dominance, hypothyroidism, PCOS, perimenopause	Absent or insufficient progesterone leaves the uterine lining thick and unstable
Structural	Uterine fibroids, endometrial polyps, adenomyosis, endometriosis	Increased endometrial surface area or impaired haemostasis at the uterine level
Other	Von Willebrand disease, anticoagulant medications, copper IUD, endometrial hyperplasia	Systemic clotting defects or medication effects on blood loss

The hormonal pathway is worth unpacking. When ovulation does not occur — whether due to polycystic ovary syndrome (PCOS), perimenopause, or stress — progesterone is not produced in the second half of the cycle. Estrogen continues to stimulate the uterine lining unchecked, producing a thick, unstable endometrium that sheds heavily and irregularly. Thyroid dysfunction, both hypothyroidism and hyperthyroidism, disrupts this hormonal balance and can independently drive heavy bleeding.

Among structural causes, submucosal fibroids — those protruding into the uterine cavity — cause the heaviest bleeding by enlarging the shedding surface and interfering with the normal mechanisms that stop menstrual flow. Adenomyosis, where endometrial tissue grows into the uterine muscle wall, produces a heavy, crampy period that is often underdiagnosed.

Von Willebrand disease and other coagulation disorders are underrecognized, particularly in younger women who have had heavy periods since adolescence. Studies suggest bleeding disorders account for heavy menstrual bleeding in up to 20% of adolescents referred for evaluation.

Symptoms and diagnosis

Common presentations include:

• Soaking through a pad or tampon every 1–2 hours for several consecutive hours
• Passing blood clots larger than a 50-cent coin
• Bleeding lasting more than 7 days
• Flooding through clothing or bedding overnight
• Restricting work, exercise, or social plans because of flow
• Fatigue, breathlessness, pallor, or light-headedness from iron deficiency anaemia

A standard diagnostic workup includes:

1. Clinical history — menstrual pattern, clot size, impact on daily life
2. Full blood count — to detect anaemia
3. Ferritin (iron studies) — to identify iron deficiency before anaemia becomes overt
4. TSH — to rule out thyroid dysfunction
5. Coagulation screen and von Willebrand factor testing — especially in adolescents or women with heavy periods since menarche
6. Pelvic ultrasound — to identify fibroids, polyps, adenomyosis, or ovarian pathology; available through LifeLabs, Dynacare, or hospital imaging across Canada
7. Endometrial biopsy — recommended for women over 45 or those with risk factors for endometrial hyperplasia or cancer
8. Hysteroscopy — direct visualization of the uterine cavity; the reference standard for intrauterine pathology

Treatment options

Treatment depends on the underlying cause, symptom severity, desire for future pregnancy, and patient preference.

Medical management:

• Levonorgestrel intrauterine system (LNG-IUS / Mirena): The most effective non-surgical option, reducing blood loss by up to 90% in clinical studies. It also provides contraception and is listed on most provincial drug benefit formularies in Canada, though coverage criteria vary by province.
• Combined oral contraceptive pill: Regulates cycles and reduces blood loss; widely available and covered under most provincial pharmacare plans for eligible patients.
• Oral progestogens (norethisterone): Used cyclically in the luteal phase to stabilize the endometrium when estrogen dominance or anovulation is the driver.
• Tranexamic acid: An antifibrinolytic taken only during menstruation; reduces blood loss by up to 50% with no hormonal effect. Useful for women who cannot or prefer not to use hormonal therapy.
• NSAIDs (mefenamic acid, ibuprofen): Reduce prostaglandin-driven blood loss and relieve period pain; effective as a short-term option.
• Iron supplementation: Essential when anaemia is present; treating the bleeding alone is not sufficient if iron stores are already depleted.
• Treating the underlying cause: Levothyroxine for hypothyroidism; PCOS management for anovulatory cycles.

Surgical management (for women who have completed their family or where medical management has failed):

• Endometrial ablation: Minimally invasive destruction of the uterine lining; highly effective for women not seeking future pregnancy.
• Myomectomy: Surgical removal of fibroids while preserving the uterus.
• Uterine artery embolization (UAE): A radiological procedure that reduces blood supply to fibroids; available at major Canadian academic centres.
• Hysterectomy: Definitive cure; appropriate when other treatments have failed or are declined.

When to see a clinician in Canada

See a family physician, nurse practitioner, or gynaecologist if:

• You are soaking through protection every hour or two for several consecutive hours
• Your period consistently lasts longer than 7 days
• You are passing clots larger than a 50-cent coin
• Heavy bleeding is affecting your work, sleep, or daily activities
• You have fatigue, breathlessness, or dizziness that may signal anaemia
• You are over 45 and have noticed a change in your bleeding pattern — this warrants investigation to exclude endometrial pathology

Heavy periods are common but not inevitable. Effective treatments exist across the spectrum from medication to minimally invasive procedures. Canadians without a regular family physician can access initial assessment through walk-in clinics or virtual care platforms such as Maple, Felix, or Cleo, though pelvic imaging and specialist referral will still require in-person follow-up.

Limitations and open questions

Research is still emerging on several aspects of menorrhagia management. The long-term outcomes of endometrial ablation — including rates of subsequent hysterectomy and post-ablation syndrome — are not fully characterized in large Canadian cohorts. Evidence on optimal management of heavy menstrual bleeding in adolescents with bleeding disorders remains limited, and screening for von Willebrand disease is inconsistently applied in Canadian practice. Health Canada has not issued specific national guidelines on menorrhagia; Canadian clinicians largely follow NICE NG88 (UK) or Society of Obstetricians and Gynaecologists of Canada (SOGC) guidance on related conditions. The degree to which virtual-care prescribing of hormonal treatments for HMB is safe and effective without in-person pelvic assessment has not been formally studied. Patient-reported outcome measures — rather than measured blood loss — are increasingly recognized as the more clinically meaningful endpoint, but standardized tools are not yet uniformly used in Canadian practice.