Some people who see a doctor for severe period pain are diagnosed with uterine fibroids or adenomyosis. The names are similar, so the two are easily mistaken for the same condition, but they differ completely in where they arise and in their nature, and different criteria apply when deciding on treatment.
In short, for both conditions surgery is rarely considered at the moment of diagnosis. The usual approach is to start with medication and hormone treatment, according to how severe the symptoms are and whether a pregnancy is planned.
How do uterine fibroids and adenomyosis differ?
A uterine fibroid is a lump that forms in the muscle of the uterus. It is a common benign tumour, experienced by 40 to 50% of women of reproductive age, and it causes period pain and heavy menstrual bleeding. Depending on where it forms, it is classed as intramural, subserosal or submucosal, and the symptoms differ accordingly.
Adenomyosis is not a lump. It is a condition in which tissue from the uterine lining grows into the muscle layer, making the uterine wall thicker. It causes lower abdominal pain and very heavy periods, and it interferes with implantation, raising the risk of infertility. In many cases the pain is severe enough that painkillers do little to relieve it.
- Intramural fibroids — at 5cm or larger, they can cause heavy periods and dizziness from anaemia
- Subserosal fibroids — as they grow, they press on the bladder, causing frequent urination or a feeling of fullness
- Submucosal fibroids — even when small, they interfere with implantation and raise the risk of infertility
How are uterine fibroids and adenomyosis told apart?
The two conditions are distinguished by whether there is a lump or tissue invasion, by the intensity of period pain, by the pattern of bleeding and by ultrasound findings. Uterine fibroids can also bring period pain and changes in menstrual flow, but adenomyosis is characterised in almost all patients by a sharp increase in bleeding and pain that painkillers do little to relieve.
Neither can be said with certainty to be more dangerous, but adenomyosis needs careful management because its symptoms are more pronounced and it interferes with implantation more readily. Research has also found that pelvic pain is greater when the two conditions occur together.
What problems arise when uterine fibroids and adenomyosis occur together?
In a study that examined cases in which adenomyosis and uterine fibroids occurred together, 159 of 560 participants in total had both conditions and the remaining 401 had uterine fibroids alone. Higher pelvic pain scores were reported in the women who had both conditions.
Left untreated, this can lead to the problems below appearing together, so it is important to assess the clinical symptoms accurately before deciding on treatment. When the two conditions overlap, management can become more difficult the longer they are left untreated.
- Heavy menstrual bleeding and anaemia — bleeding increases and can lead to anaemia, causing dizziness
- Chronic pelvic pain — pain continues regardless of the cycle and can interfere with daily life
- Higher risk of infertility — interference with implantation can affect pregnancy plans
- More complex treatment — deciding on the direction of treatment becomes more difficult
What criteria decide the treatment?
Even for the same condition, the treatment plan differs according to age, the severity of symptoms and pregnancy plans, and even when pain or bleeding is severe, medication and hormone treatment are generally tried first. For adenomyosis, a Mirena device can be placed in the uterus to reduce pain and menstrual flow.
For anyone planning a pregnancy, aggressive surgery can weaken the uterine wall and lead to a risk of uterine rupture, so restoring the uterine environment with hormone treatment is the safer approach. Surgery is the last option, decided on when medication does not control the condition and fertility preservation has been taken into account.
