Endometriosis Diagnosis and Management

Endometriosis is the growth of endometrial tissue, the lining that normally sits only inside the uterus, at sites outside it: the ovaries, tubes, pelvic lining, bowel, bladder and occasionally the navel, a surgical scar or the chest. Endometriosis diagnosis rests mainly on the history and examination, supported by transvaginal ultrasound, and management follows a step-up sequence of hormonal medicines and, where needed, minimally invasive surgery.

Dr. Tripti Sharan, Senior Director - Obstetrics & Gynaecology and Head – High Risk Pregnancy, BLK-Max Super Speciality Hospital, New Delhi, India, built her approach to endometriosis around three ideas. The clinical examination comes before any scan. Medicine comes before the scalpel for most women. And every patient is different: "what works in one doesn't work in other." This guide sets out that approach end to end, and links to deeper articles on diagnosis, treatment and fertility.

What endometriosis is, and why it behaves the way it does

The endometrium has one job. Each cycle it thickens to prepare a bed for an embryo; if no pregnancy follows, it is shed as menstrual flow. Endometriotic tissue outside the uterus follows the same monthly rhythm. It responds to the same hormones, swells and bleeds at the time of the period, and that cyclical bleeding into tissues that cannot shed it is what produces pain, inflammation, scarring and cysts.

Because the tissue is, in Dr. Sharan's words, "after all, blood", and blood sticks readily to neighbouring structures, endometriosis tends to glue organs together. Tubes and ovaries become fixed to the back of the uterus or to the bowel. These adhesions explain much of the pain, much of the infertility and much of the difficulty surgeons face when they operate.

Why it happens: retrograde menstruation and the other theories

Dr. Sharan described reverse flow, or retrograde menstruation, as the most common and most plausible explanation. Menstrual blood normally flows forward from the uterus through the cervix and vagina. In retrograde menstruation part of it flows backwards through the fallopian tubes into the abdominal cavity, carrying endometrial cells onto the ovaries and other pelvic organs, where they implant and grow.

Retrograde menstruation alone cannot be the whole story, since it occurs in most women who menstruate. Several other mechanisms are thought to contribute:

• Coelomic metaplasia. Tissues that share an embryological origin with the endometrium (the coelomic epithelium) can transform into endometrial-type tissue.
• Vascular and lymphatic spread. Endometrial cells can travel along blood vessels and lymphatic channels to distant sites, which explains disease in the lungs or chest.
• Genetic predisposition. Endometriosis runs in families. "Everybody has uterus, tube and similar menstrual flow," Dr. Sharan noted, so the question is why only some women develop it.
• Immune factors. In affected women, the immune mechanisms that should clear refluxed endometrial cells fail to do so, allowing the tissue to survive and grow.
• Inflammation. An inflammatory environment in the pelvis sustains the lesions once they are established.

When a doctor in the session asked why only a minority of women with retrograde menstruation develop clinically significant disease, Dr. Sharan was candid that no textbook has a definitive answer: "till date, one has not been able to pinpoint as to what is exactly causing it."

Where endometriosis is found

Endometriosis is found most often in the pelvis, with the ovary the most common site, but it can also occur well beyond it. Dr. Sharan divides the disease by location, because location determines symptoms, investigations and the risks of treatment.

• Pelvic endometriosis involves the uterus, tubes, ovaries and the peritoneum, the thin lining of the pelvis.
• Extra-pelvic endometriosis lies beyond the pelvis: on the bowel, in the urinary tract, at the umbilicus, in the abdominal wall or a surgical scar, and occasionally in the chest and lungs.

Within these sites the disease takes several forms. Superficial peritoneal implants look like small spots or scarring on the pelvic lining. Ovarian endometriomas, known as chocolate cysts, are blood-filled cysts whose altered, dark brown contents give them their name. Deep infiltrating endometriosis grows into the ligaments, cervix, bowel wall or ureters, and is the hardest form to treat safely. Adenomyosis, endometrial tissue growing within the muscular wall of the uterus itself, is closely related: Dr. Sharan regards it as a type of endometriosis and estimated that around 50 to 60% of women with endometriosis have a degree of adenomyosis as well, while stressing that she could not give an exact rate.

The symptoms that point to endometriosis

Pain is the most common presenting symptom, and the character of the pain matters more than its presence. Period pain is common. Endometriosis pain is severe, lasts through all four or five days of the period rather than one or two, and needs repeated painkillers. Other symptoms follow the site of disease: deep pain during intercourse, pain on passing urine or stools around the period, abnormal bleeding patterns when the ovaries are involved, and cyclical swelling and bleeding at the navel or a caesarean scar.

Infertility, Dr. Sharan said, is now the most common presenting symptom after pain. The full symptom picture, the examination findings and the tests are covered in the diagnosis article.

Endometriosis diagnosis: examination before investigation

Dr. Sharan's first principle is that investigations never replace a careful history and examination: "Whatever investigation you do does not take away the importance of a good, thorough clinical checkup." Symptoms tied to the menstrual cycle, tenderness behind the uterus, nodules and a uterus that cannot be moved are often enough to make the diagnosis with confidence. That principle matters most in resource-limited hospitals, where advanced imaging is not available.

A transvaginal ultrasound, in which the scanning probe is placed in the vagina close to the pelvic organs, is the key supporting test; CA-125, a blood marker, is often raised; and laparoscopy, in which a telescope is passed into the abdomen, allows the surgeon to see the whole pelvis under magnification and treat lesions in the same sitting. Dr. Sharan described laparoscopy as the gold standard; how it fits alongside imaging under current guidance is covered in the diagnosis article.

Endometriosis management: from watchful waiting to surgery

Not every case needs treatment. Endometriosis found incidentally on a scan in a woman without symptoms can simply be watched with periodic ultrasound. Treatment begins when there are symptoms or infertility, and it proceeds in steps.

1. Medicines come first for most women. Combined oral contraceptive pills and progestogens are the mainstay; a hormone-releasing intrauterine device (Mirena), GnRH-based drugs (which switch off the ovaries' hormone production) and aromatase inhibitors follow when needed. The aim of all of them is to stop menstruation, because when the periods stop, the ectopic glands regress.
2. Minimally invasive surgery, laparoscopic or robotic, is used when medicines fail, when a woman needs to conceive and cannot wait one or two years, or when a cyst is large. Dr. Sharan's working threshold for removing an endometrioma is about 5 centimetres (see the cost of ovarian cystectomy).
3. Open surgery is now uncommon, reserved for very large lesions, repeated recurrence and failure of other treatment.
4. Removal of the ovaries, tubes and sometimes the uterus is a last resort for women with repeated recurrence who have completed their family and are older, because removing the ovaries at a young age brings on menopause.

Her advice on sequencing is practical: start with the commonest, most widely used drug and escalate only if needed, "because if you start from the top, then you cannot go down." The treatment article covers each drug, the surgical options and recurrence prevention in detail.

A recurring condition that needs a long-term plan

"Endometriosis is a tendency," Dr. Sharan told the audience. Removing a cyst does not remove the tendency that produced it, so cysts can form again. Women who keep their uterus and ovaries after surgery therefore usually continue with medical treatment afterwards, such as contraceptive pills, GnRH agonist injections or a Mirena, to prevent recurrence. Simple scheduling also helps: she times procedures such as hysterosalpingography (HSG, the X-ray dye test of tubal patency) and elective surgery for the days just after a period, when there is less endometrium to push into the abdomen and less bleeding.

Endometriosis and fertility

Endometriosis impairs fertility through several routes at once: tubes that are stuck and cannot pick up the egg, ovaries that fail to release eggs, an inflamed pelvis that is hostile to sperm, and an endometrium less able to accept an embryo. Ovarian reserve is not usually the main problem, but a large endometrioma can destroy ovarian tissue, and surgery on the ovary can destroy more. Dr. Sharan's caution about operating on young women who have not completed their family, her approach to women planning a pregnancy, and her view on egg freezing before extensive surgery are set out in the fertility article. For the separate question of which endometriosis and tubal problems to correct surgically before IVF, see endometriosis and tubal surgery before IVF from Dr. Shelly Singh's masterclass.

Cancer risk and the effect of menopause

Asked about malignant transformation, Dr. Sharan described the risk as very low and noted that there is little a clinician can do specifically to prevent it beyond treating the disease. Combined oral contraceptive pills, a mainstay of treatment, are themselves associated with a lower risk of ovarian cancer. Population studies do link endometriosis with a modestly higher risk of two ovarian cancer types (clear cell and endometrioid), but the absolute risk for an individual woman remains low. Because the disease depends on oestrogen, it usually subsides after menopause.

The clinical philosophy behind the approach

Dr. Sharan closed the session by describing endometriosis as distressing for patients and confusing for doctors: "even after seeing so many endometriosis patients, every patient is different." Some respond well to oral contraceptive pills, others to a Mirena, others to elagolix, an oral GnRH antagonist. The clinician's task is to know the options, start low, escalate deliberately and make an individual decision for each woman. All 19 questions the audience put to her, from GnRH suppression to urinary tract disease, are answered in the Live Discussion. More from the obstetrics and gynaecology specialty is collected on its hub page.