A normal menstrual cycle lasts between 21 to 35 days. Day one of the cycle is always the first day of menstrual bleeding (also known as having your period). Menstrual bleeding typically lasts for between 2 and 7 days and is generally considered a good thing because it is a sign that ovulation has occurred. Normal ovulation is essential for maintaining healthy levels of oestrogen and progesterone. Whilst these two hormones play a pivotal role during pregnancy, their beneficial effects are not limited to this; they are also vital for maintaining general health and help to protect against osteoporosis, breast cancer and heart disease.
Abnormal uterine bleeding affects 2-5% of women of reproductive age. It occurs when the cycle length and period duration differ from the normal values. It is a broad term that also encompasses bleeding or spotting between periods. Unfortunately this wide categorisation means that there are many potential causes of abnormal uterine bleeding and, often, diagnosis becomes a process of elimination.
When abnormal uterine bleeding takes the form of prolonged, or heavy bleeding it is termed menorrhagia. Medically a ‘heavy’ period is defined as losing more than 80ml blood and/or it having a duration of over 7 days. Young teenagers and perimenopausal women are at most risk. For young teenagers it is usually just a case of their bodies settling into a regular cycle. Treatment options range from non-steroidal anti-inflammatory drugs, which block prostaglandins (easing painful period cramps) and reduce menstrual flow; to hormonal treatment, such as the combined oral contraceptive pill, which stabilises the endometrial lining and ensures controlled monthly bleeds; to hysterectomies, in the most severe cases.
Broadly speaking, abnormal uterine bleeding occurs because of structural abnormalities, lifestyle disruptions or ovulation disorders.
These can include benign lesions such as fibroids, polyps and adenomyosis, as well as lesions of the cervix and the vagina. Endometriosis is a well characterised condition that results from a build-up of endometrial-like tissue elsewhere in the body; chronic period pain and heavy periods are two of the main symptoms. Complications during the early stages of pregnancy, such as miscarriage and ectopic pregnancy can also cause abnormal bleeding. Sometimes women who have an intrauterine device (IUD) fitted for contraception will experience abnormal bleeding.
Most structural abnormalities can be identified with ultrasound; for lesions deep within the pelvic region, a high resolution transvaginal ultrasound is a very useful diagnostic aid. Occasionally surgery will be required; hysteroscopies (within the uterine cavity) and laparoscopies (outside the uterus) can be used for both diagnosis and ablation of unwanted lesions.
Certain medications and medical conditions can disrupt the menstrual cycle. Diabetes is one example. There appears to be some association between insulin resistance and a thickening of the uterine lining, the latter of which results in heavy periods. Emotional and physical stress can cause the menstrual cycle to become irregular, as can obesity (BMI >30) and smoking. These are known as modifiable risk factors because through making behavioural adjustments, the risk of experiencing menstrual irregularities is reduced.
If no other cause can be established for abnormal uterine bleeding then an ovulation disorder will probably be diagnosed. These are classed as dysfunctional uterine bleeding and the most common examples are polycystic ovary syndrome (PCOS), thyroid disease and premature ovarian insufficiency.
Thyroid disease is frequently misdiagnosed as PCOS because it shares a number of common symptoms, including anovulation and hair loss. However, thyroid disease itself has a strong association with irregular menstrual cycles. One study found that 44% of people with menstrual disorders had an underlying thyroid issue. The predominant thyroid issue is hypothyroidism (an underactive thyroid), which suppresses ovulation, impairs insulin sensitivity and reduces the availability of cellular energy (ATP). Normal ovarian function requires significant energy.
The advantage to finding out you have an ovulation disorder is that often it is reversible with changes to the diet and lifestyle. For example, losing weight can improve the symptoms of PCOS.
Premature ovarian insufficiency is one case where lifestyle modifications will unfortunately not help. It happens when the ovaries stop producing eggs and can come on gradually or occur suddenly. The first sign of the condition will usually be irregular menstrual cycles. In 50% of cases the cause is unknown, although there is thought to be a familial component. This condition can also occur in women who have undergone radiotherapy or chemotherapy. Symptoms can be alleviated with hormone replacement therapy, but to date there is no cure.
Unfortunately doctors are often unsure how best to manage abnormal uterine bleeding and treatment is, at best, random and speculative, and at worst, ineffective. It is of fundamental importance to identify the reasons for your irregular cycles and abnormal bleeding because only that way will you be able to find a solution that provides complete symptomatic relief.
- Ajmani, N S, et al. “Role of Thyroid Dysfunction in Patients with Menstrual Disorders in Tertiary Care Center of Walled City of Delhi.” Journal of Obstetrics and Gynaecology of India , vol. 66, no. 2, Apr. 2016, pp. 115–119., doi:10.1007/s13224-014-0650-0.
- Bae, J, et al. “Factors Associated with Menstrual Cycle Irregularity and Menopause.” BMC Women’s Health, vol. 18, no. 1, 6 Feb. 2018, p. 36., doi:10.1186/s12905-018-0528-x.
- Koutras, D A. “Disturbances of Menstruation in Thyroid Disease.” Annals of the New York Academy of Sciences, vol. 816, 17 June 1997, pp. 280–284.
- “Abnormal Uterine Bleeding (Booklet).” ReproductiveFacts.org, The American Society for Reproductive Medicine, www.reproductivefacts.org/news-and-publications/patient-fact-sheets-and-booklets/documents/fact-sheets-and-info-booklets/abnormal-uterine-bleeding/. Revised 2012.
- “What Is Premature Ovarian Insufficiency (Also Called Premature Ovarian Failure)? .” ReproductiveFacts.org, The American Society for Reproductive Medicine, www.reproductivefacts.org/news-and-publications/patient-fact-sheets-and-booklets/documents/fact-sheets-and-info-booklets/what-is-premature-ovarian-insufficiency-also-called-premature-ovarian-failure/. Revised 2015.
- Briden, L. “Irregular Periods? It Could Be Your Thyroid.” Lara Briden – The Period Revolutionary, 31 Oct. 2014, www.larabriden.com/irregular-periods-think-about-thyroid/.
- “Overview: Heavy Periods.” NHS, www.nhs.uk/conditions/heavy-periods/. Page last reviewed: 07/06/2018.