Adenomyosis is a condition that affects the uterus — one that is significantly more common than most women realise, yet frequently goes undiagnosed for years. Heavy periods, debilitating cramps, and pelvic pain are the most recognisable symptoms; an enlarged, tender uterus is the most consistent clinical finding. For many women, these symptoms have been dismissed as simply 'bad periods' for years before a diagnosis is reached.
Understanding what adenomyosis is, how it is diagnosed, and what treatment options are available is the first step toward managing a condition that has a direct impact on quality of life — and, for women trying to conceive, on fertility.
Adenomyosis occurs when the endometrium — the tissue that normally lines the inside of the uterus — grows into the myometrium, the thick muscular wall of the uterus. The displaced endometrial tissue continues to behave as it would inside the uterus: it thickens in response to oestrogen, sheds during menstruation, and bleeds. But because it is embedded within the muscle wall, there is nowhere for this blood to go.
The result is a uterus that is thickened, often enlarged, and inflamed — one that contracts more forcefully during menstruation (causing severe cramps) and bleeds more heavily and for longer than normal. The condition may be diffuse — spread throughout the uterine wall — or focal, where it forms a localised mass called an adenomyoma.
Symptoms vary considerably between women. Some have no symptoms at all and the condition is found incidentally during an ultrasound. Others experience severe, debilitating symptoms that significantly impair daily life.
Common symptoms
The exact cause of adenomyosis is not fully established, but several mechanisms are proposed — and it is likely that more than one contributes in any individual patient.
Adenomyosis can affect any woman of reproductive age, but is most commonly diagnosed in women aged 35–50. Several factors are associated with increased risk:
Importantly, adenomyosis is not caused by stress, diet, or lifestyle choices. It is a structural condition driven by hormonal and inflammatory mechanisms.
Adenomyosis is associated with subfertility and pregnancy complications in some women, though the precise impact varies and many women with adenomyosis conceive and deliver without difficulty. The proposed mechanisms include impaired uterine receptivity, disrupted implantation, and altered uterine contractility during the implantation window.
Adenomyosis does not preclude pregnancy. But it is important that women who are trying to conceive have the condition identified and appropriately managed rather than having fertility treatment proceed without addressing the uterine environment.
Adenomyosis cannot be definitively diagnosed on the basis of symptoms alone — the symptom profile overlaps with other uterine conditions including fibroids, endometriosis, and polyps. A structured diagnostic approach is required.
A thorough menstrual history, pelvic pain history, sexual history, and fertility history gives the gynaecologist important clinical context. Pelvic examination may reveal a diffusely enlarged, tender uterus — but a normal examination does not exclude adenomyosis.
Transvaginal ultrasound (TVUS) is the first-line imaging investigation. It can identify features associated with adenomyosis — asymmetric uterine thickening, myometrial cysts, a heterogeneous myometrium, and loss of the clear junctional zone between endometrium and muscle. It is widely available, well-tolerated, and can also identify coexisting fibroids or ovarian cysts.
MRI provides a more detailed assessment of the uterus and is the most accurate non-invasive diagnostic tool for adenomyosis. It clearly delineates the junctional zone, identifies focal adenomyomas, and helps distinguish adenomyosis from fibroids — a distinction that is clinically important because the treatment approach differs. MRI is recommended when ultrasound findings are inconclusive, when surgical planning is required, or when the extent of disease needs precise characterisation.
CA-125 — a tumour marker most commonly associated with ovarian cancer — can be mildly elevated in adenomyosis and endometriosis. It is not a diagnostic test for adenomyosis but may be measured to exclude other pathology. A full blood count to assess for iron-deficiency anaemia is important given the frequency of heavy bleeding.
Historically, a definitive diagnosis of adenomyosis required histological examination of the uterus — effectively only possible after hysterectomy. With improvements in ultrasound and MRI technology, clinical diagnosis is now made with sufficient confidence to guide treatment in most cases without surgical confirmation.
