Endometriosis

Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside it — most often on the ovaries, the ligaments holding the uterus, the surface of the bowel and the lining of the pelvis. It is common, it is often missed for years, and it is one reason a woman with regular cycles and a normal semen analysis in her partner may still not conceive.

This page sets out what is known about endometriosis, what treatment realistically achieves, and where fertility treatment fits. Where the evidence is weak, it says so.

On this page

• What endometriosis is
• How common it is
• Symptoms, and why diagnosis is late
• How endometriosis affects fertility
• How it is diagnosed
• Stages, and what they do not tell you
• Medical treatment
• Surgery
• Fertility treatment with endometriosis
• What happens at a first consultation
• Questions patients ask

What endometriosis is

The tissue growing outside the uterus behaves a little like the lining inside it. It responds to the hormones of the menstrual cycle and it bleeds. Because that blood cannot drain, it causes inflammation, scarring and adhesions — bands of scar tissue that stick organs to one another.

Deposits are described by where they sit. Superficial disease lies on the pelvic lining. An endometrioma is a cyst of old blood inside an ovary, sometimes called a chocolate cyst. Deep infiltrating disease grows into tissue and can involve the bowel, bladder or the ligaments behind the uterus.

It is not an infection, it is not sexually transmitted, and it is not caused by anything you did. Several mechanisms are proposed, including retrograde menstruation and altered immune clearance, and none explains every case.

How common it is

Endometriosis affects roughly 10% of women and girls of reproductive age worldwide, according to the World Health Organization. Among women investigated for infertility the proportion is higher, and higher again among women with chronic pelvic pain.

Those are prevalence estimates from the published literature, not a prediction about you. Two women with the same extent of disease on a scan can have completely different symptoms and completely different fertility.

Symptoms, and why diagnosis is late

The classic pattern is pain that tracks the cycle: period pain starting before the bleeding and needing medication, pain during or after sex, pain on opening the bowels or passing urine around a period, and a deep ache in the pelvis, back or thighs.

Heavy or irregular bleeding, bowel symptoms that flare with the cycle, and fatigue are also common — and overlap with other menstrual disorders. Some women have no pain at all, and the condition is found only when they are investigated for not conceiving.

Diagnosis of endometriosis is delayed by years in most health systems. Severe period pain gets normalised, symptoms are mistaken for irritable bowel or urinary conditions, and a normal scan is wrongly taken as proof that nothing is wrong. The NHS overview of endometriosis is a useful plain-English starting point.

If pain stops you working, studying or sleeping, that is not normal and deserves investigation. Ask for a review rather than a stronger painkiller.

How endometriosis affects fertility

There are several routes, and more than one can operate at once. Adhesions distort the anatomy so the tube cannot pick up an egg from the ovary. Disease in or around a tube can block it outright.

Inflammation in the pelvic fluid appears to impair sperm function, fertilisation and early embryo development. Endometriomas reduce the volume of healthy ovarian tissue and may lower the number of eggs available. Some evidence suggests the lining of the uterus becomes less receptive.

What follows matters. Many women with endometriosis conceive with no help at all. Endometriosis lowers the monthly chance of conception on average; it does not make pregnancy impossible, and mild disease often needs no fertility treatment.

How endometriosis is diagnosed

Assessment starts with a careful history — where the pain is, when in the cycle it comes, how long it has been there — then an examination and a transvaginal pelvic ultrasound.

Ultrasound reliably shows endometriomas and can suggest deep disease in experienced hands, but it cannot see superficial deposits. A normal scan does not rule the condition out. MRI is used when deep disease involving bowel or bladder is suspected.

Laparoscopy — keyhole surgery with a camera — is still the only way to see superficial deposits directly. The ESHRE endometriosis guideline no longer requires laparoscopy before treating symptoms; a clinical diagnosis is accepted, which spares many women an operation.

Because fertility has two sides, both partners are evaluated before any plan is made. A semen analysis and ovarian reserve testing belong in the first round, alongside an assessment of whether the tubes are open.

Stages, and what they do not tell you

Surgeons record the extent of endometriosis as stage I to IV, from a few superficial spots to extensive disease with large endometriomas and dense adhesions.

Staging is useful shorthand between clinicians. It correlates poorly with pain — stage I can be agonising, stage IV silent — and predicts fertility only loosely. Treat the stage as a description of anatomy, not a prognosis.

Medical treatment

Hormonal treatment for endometriosis suppresses the cycle so deposits are not repeatedly stimulated. The combined pill, progestogens, the hormonal intrauterine system and GnRH analogues all reduce pain for many women.

The honest limitation: each works by preventing ovulation or thinning the lining, so none can be used while you are trying to conceive. Hormonal suppression does not improve natural fertility and should not be prescribed for that purpose.

Sequencing therefore matters. If pain is the priority, medical treatment is reasonable. If pregnancy is the priority now, the plan must be built from options compatible with conceiving. Those two aims sometimes pull in opposite directions, and that is worth saying out loud in the consultation.

Surgery

Laparoscopic surgery for endometriosis removes or destroys deposits, frees adhesions, and drains or excises endometriomas. For pain it helps most women, though symptoms return in a proportion of cases and repeat surgery gets progressively harder.

For fertility the picture is mixed. Surgery for minimal to mild disease gives a small improvement in the chance of natural conception. Removing an endometrioma can relieve pain and improve access to the ovary at egg collection, but it also removes normal ovarian tissue and may reduce the egg supply.

That trade-off is the central decision. Repeated ovarian surgery risks leaving too little ovarian tissue behind. If reserve is already low, or you are over 35, or one ovarian operation has already been done, moving to IVF is often wiser than operating again.

Fertility treatment with endometriosis

With mild disease, open tubes and a normal semen analysis, timed intercourse or intrauterine insemination with mild stimulation is a reasonable first step, for a defined number of cycles rather than indefinitely.

IVF bypasses the pelvis altogether. That is why it is used when tubes are damaged, when endometriosis is moderate or severe, when sperm quality is also affected, or when simpler treatment has not worked. Egg numbers may be lower where endometriomas are present.

Add-ons are offered selectively here, not routinely. The endometrial receptivity array is the example: it was used in more than 750 patients at this clinic and is no longer offered. Anything suggested to you should have to justify itself the same way.

What happens at a first consultation

The first appointment establishes what is actually happening, in both partners, before anything is recommended: full history, examination, pelvic scan, blood tests including ovarian reserve, an assessment of the tubes, and a semen analysis.

If the tubes need checking, that may be a hysterosalpingogram or a HyCoSy. If the uterine cavity looks abnormal, hysteroscopy may be added. Only then is a plan discussed, with its reasoning, its alternatives, and the option of waiting.

Questions patients ask

Can endometriosis come back after surgery? Yes. Return of symptoms over several years is well documented. Hormonal treatment afterwards reduces recurrence, but only while you are not trying to conceive.

Does pregnancy cure it? No. Symptoms often settle during pregnancy and breastfeeding because ovulation stops, and usually return when cycles do.

Is it hereditary? There is a familial tendency. A mother or sister with endometriosis raises your own likelihood, which is a good reason to mention family history early.

Can diet or exercise fix it? Neither removes deposits. Regular activity, sleep, pelvic floor physiotherapy and proper pain management genuinely improve quality of life, and none do harm.

Should I freeze eggs before endometriosis surgery? It is worth discussing if reserve is already reduced or surgery will be extensive. It is a decision to make before the operation, not after.

Written and medically reviewed by Dr. Vani Sundarapandian, MD, DGO, FRCOG (UK) — founder and Medical Director, Jananam Fertility Centre, Chennai.