What is endometriosis — Complete 2026 guide

Endometriosis affects approximately 190 million women worldwide — 1 in 10 women of reproductive age. In Romania, the average time to a correct diagnosis is 7–10 years. This complete guide gives you everything you need to know about endometriosis: from symptoms and diagnosis to the latest treatment options in 2026.

What is endometriosis — the 2026 medical definition

Endometriosis is a chronic inflammatory disease characterized by the presence of tissue similar to the endometrium (the lining of the uterus) outside the uterine cavity. This ectopic tissue responds to the hormonal fluctuations of the menstrual cycle — it thickens, breaks down, and bleeds, just like normal endometrium.

The crucial difference: it has no way out. With no route for elimination, endometriotic tissue causes:

• Chronic inflammation — the immune system reacts constantly
• Adhesions — organs stick to one another
• Scarring — the structure of pelvic organs is altered
• Cysts — especially on the ovaries (endometriomas)
• Fibrotic nodules — in the deep infiltrating form

Causes and risk factors

The exact cause of endometriosis is not yet fully understood, but research over the past 20 years has identified several contributing factors:

1. Retrograde menstruation (Sampson’s theory)

During menstruation, blood containing endometrial cells flows backward through the fallopian tubes into the pelvic cavity. These cells can adhere to the peritoneum and grow there. It is the most widely accepted theory, but it does not explain every case.

2. Genetic factors

The risk of endometriosis is 5–7 times higher if you have a first-degree relative (mother, sister) with the disease. Genetic studies have identified specific variants associated with increased risk.

3. Immune dysfunction

In healthy women, the immune system clears endometrial cells that reach outside the uterus. In women with endometriosis, this mechanism does not work correctly — the immune system does not recognize the tissue as “foreign”.

4. Hormones and estrogen

Endometriosis is an estrogen-dependent disease. Higher estrogen levels or increased sensitivity to estrogen worsen the disease.

5. Environmental and lifestyle factors

• Exposure to endocrine disruptors (BPA, phthalates)
• Diet high in trans fats and low in omega-3
• High alcohol consumption
• Lack of regular physical activity

Identified risk factors

The 4 types of endometriosis

In 2026, the international classification recognizes 4 main forms of endometriosis, often present at the same time in the same patient:

1. Superficial peritoneal endometriosis

What it is: Small lesions (under 5 mm) on the surface of the pelvic peritoneum.

Symptoms: Severe menstrual pain, pelvic pain.

Diagnosis: Only by laparoscopy (not visible on ultrasound).

Treatment: Surgical excision at laparoscopy.

2. Ovarian endometrioma (“chocolate cyst”)

What it is: Ovarian cyst containing old, clotted blood (chocolate-like appearance).

Symptoms: Pelvic pain, sometimes asymptomatic until it becomes large.

Diagnosis: Transvaginal ultrasound detects it with specificity above 95%.

Treatment: Ovarian cystectomy with preservation of healthy ovarian tissue.

3. Deep infiltrating endometriosis (DIE)

What it is: Fibrotic nodules that penetrate adjacent organs — bladder, rectum, uterosacral ligaments, rectovaginal septum.

Symptoms: Severe pain during intercourse, urination, and defecation — especially cyclic.

Diagnosis: IDEA ultrasound (internationally standardized protocol) + pelvic MRI.

Treatment: Da Vinci robotic surgery or advanced laparoscopy — requires specific expertise.

4. Adenomyosis (uterine endometriosis)

What it is: Endometrial tissue invades the muscle of the uterus (myometrium).

Symptoms: Very heavy periods, intense pain, enlarged uterus.

Diagnosis: Transvaginal ultrasound + MRI.

Treatment: Hormonal (levonorgestrel IUD), or surgical in severe cases.

Endometriosis symptoms — complete checklist

Endometriosis presents very differently from one woman to another. Sometimes symptoms are severe with mild disease; other times they are subtle even when the disease is advanced. Here are all the possible symptoms:

⚠️ When to see a specialist

See a gynecologist who specializes in endometriosis right away if:

• You have menstrual pain that keeps you from working or going to school
• Anti-inflammatories do not help, or help only temporarily
• You have chronic pelvic pain, even outside menstruation
• Intercourse is painful
• You have not been able to conceive for more than 12 months (6 months if you are over 35)

Diagnosing endometriosis — 4 steps

Modern endometriosis diagnosis no longer depends exclusively on laparoscopy. In 2026, we have precise tools for non-invasive diagnosis:

Step 1: Detailed medical history

A specialized gynecologist will explore:

• Your complete menstrual history
• Your symptoms and their intensity
• The impact on your daily life
• Family history of endometriosis
• Previous treatments

Step 2: Specialized transvaginal ultrasound (IDEA protocol)

IDEA (International Deep Endometriosis Analysis) is the standardized protocol for systematic ultrasound assessment. It requires an examiner with specific training.

An IDEA ultrasound evaluates:

• The uterus (adenomyosis)
• The ovaries (endometriomas)
• The pouch of Douglas (“sliding sign”)
• The uterosacral ligaments
• The rectovaginal septum
• The bladder
• The rectum and sigmoid colon

Step 3: Pelvic MRI (if needed)

MRI is used when:

• Ultrasound suggests complex DIE
• A major surgical procedure is being planned
• There is suspicion of extrapelvic endometriosis (diaphragm, umbilicus)

Step 4: Laparoscopy (if needed)

Laparoscopy remains the reference standard for definitive diagnosis, but in 2026 it is no longer the first step. It is needed only when:

• Non-invasive diagnosis is not conclusive
• Surgical treatment is planned (diagnosis + treatment in the same procedure)

Endometriosis treatment — all the options

There is no single treatment that suits every patient with endometriosis. The optimal plan depends on: symptom severity, disease stage, age, and desire for pregnancy.

A. Medical (hormonal) treatment

When it is recommended: Mild to moderate symptoms, no severe DIE, when pregnancy is not being pursued in the immediate term.

1. Combined oral contraceptives

Suppress ovulation and menstruation, which reduces the growth of endometriotic tissue.
Effectiveness: 70–80% symptom improvement.

2. Progestins (dienogest, levonorgestrel IUD)

Lower estrogen and shrink endometriotic tissue.
Effectiveness: 85% improvement for dysmenorrhea.

3. GnRH agonists (leuprolide)

Induce a temporary “medical menopause”. Very effective but with side effects (hot flashes, bone loss).
Used for a maximum of 3–6 months.

4. Analgesics

Non-steroidal anti-inflammatories (NSAIDs), for acute pain control. They do not treat the disease, only the symptoms.

B. Surgical treatment

When it is recommended: DIE, large ovarian endometriomas, associated infertility, severe symptoms that do not respond to hormonal therapy.

1. Standard laparoscopy

Excision of lesions through standard laparoscopy. Recovery: 2–3 weeks.

2. Da Vinci robotic surgery

The reference standard for complex DIE. Instruments with 7 degrees of freedom, 10× magnified 3D visualization, maximum precision.

Advantages over standard laparoscopy:

• Millimetric precision in narrow anatomical spaces
• Elimination of the surgeon’s hand tremor
• High-definition three-dimensional visualization
• Faster recovery (1–2 days of hospitalization)
• Ideal for bowel surgery (rectal endometriosis)

Read more about Da Vinci robotic surgery →

3. Hysterectomy

Indicated only in severe cases, for women who no longer wish to have children and have exhausted other options. It is the last resort.

C. Complementary therapies (emerging evidence)

• Anti-inflammatory diet — Mediterranean, gluten-free, reduced sugar
• Pelvic physical therapy — for pain and muscle tension
• Acupuncture — moderate evidence for pain reduction
• Yoga and mindfulness — for stress management
• Supplements — omega-3, vitamin D, magnesium, curcumin

Endometriosis and pregnancy — myths and facts

How does endometriosis affect fertility?

• Pelvic adhesions that block the fallopian tubes
• Changes in oocyte quality
• Inflammation that affects implantation
• Reduced ovarian reserve (especially with endometriomas)

How to improve your chances of conception with endometriosis

• Early diagnosis and treatment — do not delay
• Proper surgery — excision of lesions by a specialized gynecologist
• Early IVF if you are over 35 or have severe endometriosis
• Egg freezing before ovarian surgery

10 endometriosis myths debunked

1. MYTH: “Severe menstrual pain is normal.”
   FACT: Pain that keeps you from functioning is NOT normal. It is a warning sign.
2. MYTH: “Endometriosis disappears at menopause.”
   FACT: In many cases it improves, but it can persist, especially DIE.
3. MYTH: “Pregnancy cures endometriosis.”
   FACT: Pregnancy can improve symptoms temporarily, but it does not cure the disease.
4. MYTH: “Endometriosis only affects mature women.”
   FACT: It can appear from the first period (including in adolescents).
5. MYTH: “Oral contraceptives cure endometriosis.”
   FACT: They suppress the symptoms; they do not cure the disease.
6. MYTH: “Hysterectomy cures endometriosis.”
   FACT: Endometriosis can recur even after hysterectomy.
7. MYTH: “Endometriosis is a rare disease.”
   FACT: 1 in 10 women — more common than type 1 diabetes.
8. MYTH: “You cannot diagnose endometriosis without surgery.”
   FACT: Modern IDEA ultrasound detects most lesions.
9. MYTH: “Endometriosis is a psychological problem — you are exaggerating.”
   FACT: It is an organic inflammatory disease that can be diagnosed and treated.
10. MYTH: “There is nothing you can do about endometriosis.”
    FACT: Effective treatment exists. 80–95% of patients improve with the right approach.

When and how to book a consultation

If you recognize the symptoms of endometriosis or have a prior inconclusive diagnosis, book a Pre-Consultation with a gynecologist who specializes in endometriosis.

Dr. Alin Constantin — why he is a relevant specialist for you

• Vice President, European Endometriosis League (since 2026, elected in Bologna)
• 9 years of experience in Germany — Frankfurt, Hamburg, Saarland University Medical Center
• International pioneer in intraoperative ultrasound for DIE
• 8+ PubMed publications in the past 3 years
• IRCAD Strasbourg faculty — training surgeons worldwide
• Certified Da Vinci robotic surgeon
• Practices at Monza Hospital Bucharest

Book Pre-Consultation now →

Recommended related articles

• 5 endometriosis symptoms many women overlook
• Transvaginal ultrasound in diagnosing endometriosis — why standard ultrasound can miss the disease
• Robotic surgery in gynecology: what you need to know about the Da Vinci system

Last updated: July 2026 • Author: Dr. Alin Constantin, Vice President, European Endometriosis League