Endometriosis vs adenomyosis vs PMDD

Endometriosis, adenomyosis, and PMDD are three very different conditions that can all make periods and mood feel unmanageable, but they affect different parts of the body and need different approaches.

Understanding the differences is the first step to getting the right diagnosis, treatment, and a cycle tracking plan that actually helps you day to day.

What are endometriosis, adenomyosis and PMDD in simple terms?

• Endometriosis happens when tissue similar to the lining of the uterus (endometrium) grows outside the uterus, for example on the ovaries, fallopian tubes, or pelvic lining. This tissue responds to hormones, can bleed and become inflamed each cycle, causing pain and sometimes affecting fertility. (Read More)

• Adenomyosis is when the same type of tissue that lines the uterus grows into the muscular wall of the uterus, making the uterus thicker and often enlarged. It stays within the uterus but can cause very heavy and painful periods.

• PMDD (Premenstrual Dysphoric Disorder) is a severe form of premenstrual disorder where emotional and psychological symptoms (like intense mood swings, depression, or anxiety) occur in the week or two before the period, then improve a few days after bleeding starts. PMDD is classified as a mental health condition linked to the menstrual cycle, not a structural disease of the uterus. (Read More)

These conditions can coexist, which is one reason menstrual health can feel so confusing and overwhelming.

How are the symptoms of endometriosis, adenomyosis and PMDD different?

Symptom snapshot

What actually causes these conditions?

1. Why does endometriosis happen?

The exact cause of endometriosis is still unknown. Research suggests a combination of factors, including

• Retrograde menstruation (menstrual blood flowing backwards through the fallopian tubes into the pelvis).

• Immune system changes and inflammation that allow this tissue to survive and grow outside the uterus.

• Genetic and hormonal influences, as endometriosis is estrogen-sensitive and can run in families.

WHO notes that immune system dysregulation may play a key role in how endometriosis develops and persists.

2. Why does adenomyosis develop?

The cause of adenomyosis is also not fully understood, but it is linked to the movement of endometrial tissue into the uterine muscle.

It is more commonly diagnosed in people in their 30s and 40s and in those who have given birth or had uterine surgery, although it can occur in others as well. Hormonal and inflammatory mechanisms are thought to contribute.

3. What causes PMDD?

PMDD is not “just” a hormonal problem or “just” a mental health condition; it sits at the intersection of both. Evidence suggets:

• People with PMDD have a heightened sensitivity to normal cyclical changes in ovarian hormones, rather than abnormal hormone levels themselves.

• These hormonal shifts affect brain chemistry, particularly serotonin, which is why selective serotonin reuptake inhibitors (SSRIs) can be effective.

PMDD is recognised in the DSM-5-TR as a mental disorder with specific diagnostic criteria, which validates it as a real and serious condition rather than “moodiness”.

How are endometriosis, adenomyosis and PMDD diagnosed?

1. How is endometriosis diagnosed?

• A detailed symptom history and pelvic exam are usually the first step.

• Imaging (ultrasound, MRI) can suggest endometriosis, especially ovarian endometriomas, but may miss superficial lesions.

• The only way to confirm endometriosis definitively is through laparoscopy (keyhole surgery), sometimes with biopsy.

Because surgery is invasive, many clinicians may offer empirical treatment based on symptoms before or instead of surgical diagnosis.

2. How is adenomyosis diagnosed?

• Pelvic exam may reveal an enlarged, tender uterus.

• Transvaginal ultrasound and MRI can show characteristic changes in the uterine muscle and are commonly used for diagnosis.

• Historically, adenomyosis was only confirmed after hysterectomy, but modern imaging allows non-surgical diagnosis in many cases.

3. How is PMDD diagnosed?

PMDD diagnosis is based on symptoms tracked across at least two cycles, not on blood tests or scans. Key points include:

• At least five symptoms in the final week before the period, improving within a few days after onset of menses, and minimal or absent in the week after.

• At least one symptom must be a mood symptom (e.g., depressed mood, anxiety, irritability, mood swings).

• Symptoms must cause significant distress or impairment at work, school, in relationships, or daily life, and must not simply be a worsening of another mental health condition.

Daily symptom tracking is considered best practice to confirm the pattern and reach a clear diagnosis. You can use HealCycle to track your periods and your mood symptoms.

Can you have endometriosis, adenomyosis and PMDD together?

Yes, it is possible to have more than one of these conditions at the same time. For example:

• Someone may have endometriosis and adenomyosis causing severe pain and heavy bleeding, while also experiencing PMDD-related mood crashes in the luteal phase.

• Chronic pain conditions like endometriosis can worsen mental health, sometimes mimicking or coexisting with PMDD, which can make the overall picture more complex.

This is why detailed cycle tracking (including pain, bleeding, mood, energy, and function) is so valuable in teasing apart what is happening when.

When should you see a doctor for these symptoms?

You should seek professional help if you notice any of the following:

• Period pain that stops you from working, studying, or doing daily tasks, especially if it does not respond to usual painkillers.

• Very heavy periods (changing pads or cups more than usual, passing large clots, or feeling dizzy and tired) or bleeding between periods.

• Mood symptoms before your period that feel out of control, include suicidal thoughts, or significantly harm your relationships or work.

Professional bodies like ACOG and RCOG stress the importance of early assessment and a tailored management plan for endometriosis, adenomyosis, and PMDD.

References

1. World Health Organization. Endometriosis – Fact Sheet.

2. American College of Obstetricians and Gynecologists (ACOG). Endometriosis – Frequently Asked Questions.

3. WebMD. The Difference Between Endometriosis and Adenomyosis.

4. Office on Women’s Health (U.S.). Premenstrual Dysphoric Disorder (PMDD).