Reviewed February 2021

Irregular period? How to tell if it’s adenomyosis

Irregular period_ How to tell if it's adenomyosis

The average length of a menstrual cycle is about 28 days, but it is perfectly normal for it to be longer or shorter than this by up to seven days. Someone is deemed to have “irregular periods” when the gap between periods keeps changing month on month, and there is a change in your normal pattern of periods. Such changes can cause worry and concern, but there are lots of reasons for irregular periods to occur, and it doesn’t necessarily mean that something is going wrong.

For example, during times of change such as puberty, when the periods first start, they can be irregular for a year or so before a regular pattern develops. Similarly, during perimenopause (between the ages of 45 and 55 years), periods may become more irregular and lighter, as the levels of oestrogen fluctuate and the release of hormones becomes less predictable.

In the early stages of pregnancy there may be some spotting — bleeding that occurs when the fertilised embryo implants into the womb — and this can often be mistaken to be a period that has come early. Therefore, if pregnancy could be a possibility and your period seems to have come earlier than expected, it may be worthwhile taking a pregnancy test to check.

Other changes to the body, such as extreme weight loss, weight gain, excessive exercise or stress can lead to irregular periods, as the level of oestrogen released in the body is affected by these changes

Other changes to the body, such as extreme weight loss, weight gain, excessive exercise or stress can lead to irregular periods, as the level of oestrogen released in the body is affected by these changes.

In addition to lifestyle changes, taking certain medications can make periods irregular, such as use of hormonal contraception. As the body adjusts to the extra hormones delivered by contraception, periods can be irregular at first, but should subsequently settle down into a pattern that seems normal for you, although bear in mind some forms of hormonal contraception can cause your periods to stop entirely.

Finally, some medical conditions such as polycystic ovary syndrome (PCOS) and thyroid problems (such as an over- or underactive thyroid) can also cause the menstrual cycle to become erratic. Often, you would see associated symptoms that suggest these conditions are responsible, such as excessive hair growth, weight gain, and difficulty getting pregnant with PCOS. An over-active thyroid may be associated with palpitations, feeling hot all the time, tremors, and weight loss. An underactive thyroid can bring about weight gain, and feeling cold and tired all the time.

What about adenomyosis?

In addition to the conditions mentioned above, irregular periods can also be caused by problems in the womb itself, such as those occurring with a condition such as adenomyosis. Adenomyosis is a condition in which the womb lining (endometrium) moves into the muscle layer of the womb (myometrium). The condition can be found in women of all ages who still have periods, but occurs most commonly in women aged between 40 and 50, in women who have had children, and in women who have endometriosis (where womb tissue is found outside the uterus, such as in the Fallopian tubes).

It is unknown why adenomyosis occurs, but it cannot be spread between people, and it is not a form of cancer. One theory of why it occurs is that when an injury occurs in the womb, such as one sustained during childbirth, the womb lining grows abnormally inwards instead of growing back outwards.1 This growth is influenced by your genes, hormones, and immune system. It has been found that adenomyosis usually disappears after menopause when oestrogen levels fall, and as such it can be deemed that oestrogen plays a role in its development.2

Irregular periods in adenomyosis

People who have adenomyosis can experience heavy, painful, and irregular periods. It is not understood why this occurs because not all people with the condition have irregular periods and, in fact, many have no symptoms at all. For those who do have heavy and irregular periods, this may be due to the movement of the womb lining into the muscle, damaging the blood vessels in the womb, and thus causing bleeding at irregular times.

Not all women who have adenomyosis have irregular periods and, in fact, many women with the condition have no symptoms at all

The womb lining becomes thicker as it is “regrowing” into the muscle layer when menstrual bleeding occurs, and as such the shedding of more endometrial tissue leads to heavier periods. There is no way of telling if your irregular periods are definitely linked to adenomyosis as opposed to being a symptom of something else. In fact, adenomyosis is often misdiagnosed as uterine fibroids (benign tumours growing in or on the womb wall) because the symptoms are very similar with heavy, painful, and irregular periods. The only way to tell the difference is by doing further tests such as an ultrasound scan or magnetic resonance imaging (MRI).

Other symptoms of adenomyosis

Other symptoms of adenomyosis include constant pelvic pain, menstrual cramps, pain during sex and bowel movements, and pressure on the bladder. This is because the endometrial tissue growing into the uterine wall will stimulate nerves causing pain as the womb tries to contract during menstruation in order to shed the tissue. Adenomyosis does not decrease the chance of getting pregnant, but some findings indicate that when pregnancy does occur the risk of miscarriage or having a premature baby is increased.3

These symptoms vary between different people because the amount of womb affected by the ingrowing tissue is different from person to person. Some people may have all these symptoms, while 30% of people with adenomyosis do not have any symptoms at all.4

What to do if you think you have adenomyosis

If you are concerned you may have adenomyosis, you should see your GP, who may first do a physical examination: by feeling your abdomen, doctors may be able to tell if you have an enlarged and tender womb. Then your doctor may refer you to a gynaecologist or refer you for further scans. Around 50% of adenomyosis can be detected by a transvaginal ultrasound scan. This is when a probe is inserted into the vagina, and sound waves are used to tell if there is any abnormal thickening of the womb wall.

If the ultrasound scan does not show clear enough images, an MRI scan may be booked. In this, magnetic waves are used to produce a detailed and clear picture of the womb.

How do you treat adenomyosis?

There are several different ways of treating adenomyosis, and the method you will be advised to use depends on individual circumstances, such as age, fertility, previous treatments, and your personal preference. A lot of treatments are aimed at controlling symptoms: with mild symptoms, if you are pregnant, or if you are nearing menopause (when symptoms will stop anyway), you may opt to just observe the condition without acting at this stage.

If severe pain is a major concern, lifestyle measures such as yoga can help, and using a TENS (transcutaneous electrical nerve stimulation) machine can help. Medications such as ibuprofen, tranexamic acid, and mefenamic acid can also be used for pain reduction. Controlling periods can also be done by using hormonal contraception, and having GnRh-analog injections can lead to a temporary, reversible menopause, and the subsequent thinning womb lining can ease heavy periods.

If you do not wish to have (any more) children, one option is a hysterectomy, in which the whole womb is removed. Radiological interventions also exist, such as uterine artery embolism, where particles are injected into the blood vessels to block the blood supply and thus cause shedding of the tissue. This is less invasive than pregnancy and preserves fertility, but while it will reduce symptoms in the short term, it is not a long term cure. Your GP or gynaecologist will be able to discuss all your options with you.

Featured image of a photo of a person opening up a tampon over the sink, as if they were about to insert it

Last updated February 2021
Next update due 2024

Dr. Diana Chiu, MBChB (Hons) MRCP PGCERT (Med Ed) PhD

Diana received her medical degree, with honours, from the University of Manchester. She then went on to receive basic and specialist medical training within the north west of England. She carried out in-depth research in medicine and was awarded a PhD in 2016. Currently, she is finishing her medical training at a large teaching hospital, and one of her greatest interests is medical education. She is an advanced life support instructor and writes regularly for post-graduate examination websites, and also holds a PGCERT in medical education with distinction.

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  1. Leyendecker, G., et al., The pathophysiology of endometriosis and adenomyosis: tissue injury and repair, Archives of Gynecology and Obstetrics, Vol. 280, No 4, 2009, 529-538
  2. Huang, T-Z., et al., Oestrogen-induced angiogenesis promotes adenomyosis by activating the Slug-VEGF axis in endometrial epithelial cells, Journal of Cellular and Molecular Medicine, Vol. 18, No. 7, 2014, 1358-71.
  3. Maheshwari, A., et al., Adenomyosis and subfertility: A systematic review of prevalence, diagnosis, treatment and fertility outcomesHuman Reproduction Update, Vol. 18, No. 4, 2012, 374–92.
  4. Vannuccini, S., and Petraglia, F., Recent advances in understanding and managing adenomyosis, F1000 Research, 2019, no 8., F1000 Faculty Review – 283

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