Mild Endometriosis (Stage I and II)

What "mild" means

The American Society for Reproductive Medicine classifies endometriosis into four stages, based on what a surgeon sees during laparoscopy, using a point score:

The stage reflects the extent of disease, not the severity of symptoms. People with stage I can have disabling pain, while some with stage IV have little. Newer classifications also describe deep endometriosis separately.

For an overview of all stages, see endometriosis.

Symptoms

• painful periods, often starting a day or two before bleeding and getting worse over time
• pelvic pain between periods
• deep pain during sex (dyspareunia)
• pain with bowel movements or urination, especially during periods
• bloating, constipation or diarrhea, often mistaken for IBS
• heavy or irregular bleeding
• fatigue
• difficulty conceiving

Some people with mild endometriosis have no symptoms and are diagnosed during surgery for another reason or during a fertility evaluation.

Why it causes pain

Endometriosis implants respond to hormones and cause inflammation, irritating nearby nerves. They release inflammatory chemicals into the pelvis, and over time the nervous system can become more sensitive to pain (central sensitization). This explains why even small implants can be very painful.

Diagnosis

• History and pelvic exam: may find tenderness, but the exam is often normal in mild disease.
• Transvaginal ultrasound: good for endometriomas and deep nodules, but usually cannot see superficial implants. A normal scan does not rule out mild endometriosis.
• MRI: similar limitations for superficial disease.
• Laparoscopy: keyhole surgery allows direct viewing, biopsy and treatment at the same time. It remains the way to confirm and stage endometriosis.

Current guidelines support starting treatment based on symptoms (a clinical diagnosis) without first requiring surgery.

Treatment for pain

Medicines

• NSAIDs such as ibuprofen or naproxen, following the label dose, for period pain
• combined hormonal contraception, often taken continuously to reduce periods
• progestins: pills (such as dienogest or norethindrone), the levonorgestrel IUD, the implant or injection
• GnRH antagonists (elagolix, or relugolix combination therapy) or GnRH agonists for more severe pain, usually with add-back hormones to protect bones

Surgery

Laparoscopic excision (cutting out) or ablation (burning) of implants can reduce pain. Pain may return over time, so many people continue hormonal treatment afterward.

Other support

• pelvic floor physical therapy
• heat, exercise and pain management programs
• treatment of associated bowel or bladder symptoms

Mild endometriosis and fertility

Mild endometriosis is associated with somewhat lower monthly chances of pregnancy, likely due to pelvic inflammation affecting eggs, sperm and implantation. Most people with stage I to II can still conceive.

• Laparoscopic removal of implants modestly improves natural pregnancy rates in stage I to II disease.
• Ovarian stimulation with intrauterine insemination (IUI) is often the next step.
• IVF is offered if other approaches fail, or with other fertility factors.
• Hormonal treatments for pain prevent pregnancy, so they are paused when trying to conceive.

Does mild endometriosis get worse?

Not always. Studies of repeat laparoscopy show that endometriosis can progress, stay the same or regress over time. Symptoms often improve during pregnancy and after menopause.

Frequently asked questions

What is mild endometriosis?

Mild endometriosis means stage I or II disease: small, superficial patches of endometrial-like tissue outside the uterus with little scarring and no large cysts. The stage describes the amount of disease, not the amount of pain.

Can mild endometriosis cause severe pain?

Yes. Pain does not match the stage. Small implants can cause intense inflammation and nerve sensitivity, so people with stage I or II endometriosis can have severe period pain, pelvic pain and pain with sex.

Can you get pregnant with mild endometriosis?

Yes, most people with mild endometriosis can conceive, although it may take longer. Laparoscopic removal of implants, ovarian stimulation with IUI, and IVF all improve the chances if pregnancy does not happen naturally.

Will an ultrasound show mild endometriosis?

Usually not. Ultrasound and MRI can detect endometriomas and deep nodules, but they typically miss small superficial implants. A normal scan does not rule out mild endometriosis; laparoscopy can confirm it.