Around 10% of premenopausal women live with endometriosis, representing nearly 190 million people worldwide. This proportion reaches up to 50% among women seeking care for infertility. Yet the disease remains one of the most underdiagnosed conditions in gynecology: an average of 7 to 9 years elapses between the first symptoms and diagnosis, up to 12 years in some cases, and most patients consult at least three clinicians before their pain is given a name.
This diagnostic delay comes at a considerable cost: disease progression, impaired quality of life, and professional, sexual and psychological repercussions. It is partly explained by a long-dominant paradigm that made surgery the mandatory route to diagnosis. Today, this paradigm is being challenged by advances in ultrasound and MRI.
Can imaging truly shorten the patient journey? And how can non-invasive diagnosis, medical treatment and surgery be combined in such a heterogeneous disease?
A chronic, inflammatory and profoundly heterogeneous disease
Endometriosis is a chronic, inflammatory gynecological disease whose progression depends on estrogens (female hormones). It is characterized by the presence of endometrial-like tissue outside the uterine cavity: ovaries, fallopian tubes, peritoneum and, more rarely, distant organs. Although non-cancerous, it shares with malignant tumors a capacity for tissue invasion and dissemination, clonal development and the frequent presence of mutations usually described in oncology.
Menstrual reflux through the fallopian tubes is widely accepted as a contributing factor, but it occurs in almost all women, whereas only a minority develop the disease. A more recent hypothesis proposes that each lesion is a clone arising from a cell that has accumulated genetic alterations, promoted in particular by chemical aggression of the cells (oxidative stress). This heterogeneity may explain why some lesions are able to produce estrogens themselves or are insensitive to progesterone, and therefore respond variably to hormonal treatments. Heritability, estimated at around 50%, also confirms a strong genetic component.
Four subtypes are distinguished, which may coexist:
Superficial peritoneal endometriosis, with lesions on the surface of the peritoneum or of the outer lining of the pelvic organs.
Ovarian endometriosis, in the form of endometriomas (ovarian cysts).
Deep endometriosis, infiltrating more than 5 mm beneath the peritoneal surface and potentially reaching the muscular layer of the rectum, bladder or ureters.
Extrapelvic endometriosis, rare, described in the diaphragm, the thorax, the abdominal wall and even the brain.
A complex clinical diagnosis
About 90% of patients report pelvic pain: painful periods, pain outside menstruation and deep pain during sexual intercourse. Additional symptoms include painful bowel movements, cyclical urinary symptoms, moderate to severe fatigue in one in two patients, and infertility in about a quarter of them.
Diagnosis nonetheless remains complex, because symptom intensity does not correlate with the actual extent of the lesions: the number, location or type of lesions poorly predict pain. Conversely, many superficial lesions remain painless, and the disease is sometimes discovered incidentally, for instance during an infertility workup. This dissociation is explained by the coexistence of three pain mechanisms: pain related to inflammation around the lesions; nerve pain, when lesions affect or irritate the nerves; and pain sustained by the central nervous system, which amplifies pain signals. This last mechanism explains why pain can persist, or even return without any new lesion.
The overlap with other conditions (adenomyosis, fibroids, irritable bowel syndrome, interstitial cystitis, pelvic floor myalgia) further complicates the diagnostic workup. A normal clinical examination does not rule out the disease. As for biological tests (blood, saliva, urine), none has been validated: serum CA-125 testing is not reliable enough, and small circulating genetic molecules (microRNAs), although promising, still await validation in large patient cohorts.
Imaging, the cornerstone of non-invasive diagnosis
Long considered the gold standard, laparoscopy with histological confirmation is no longer a systematic prerequisite. International guidelines now accept a diagnosis based on strong clinical suspicion, grounded in symptoms, clinical examination and imaging, so as not to delay treatment.
Transvaginal ultrasound is the first-line examination. Its sensitivity reaches 93% and its specificity 96% for endometriomas, but sensitivity drops to 79% for deep endometriosis and to around 65% for superficial lesions. Augmented pelvic ultrasound, which assesses the relative position of the ovaries (“kissing ovaries” sign) and the dynamic sliding of the uterus against the rectosigmoid, achieves a sensitivity of nearly 88% for deep endometriosis.
Pelvic MRI, most often performed without contrast injection, is preferred when bowel, bladder or ureteral involvement is suspected, and for surgical planning. With a dedicated protocol and expert interpretation, it achieves a sensitivity of 91% to 93.5% and a specificity of 86% to 87.5% for deep and ovarian forms. It also assesses the other pelvic organs, looks for signs of malignancy when ultrasound is inconclusive, and detects extrapelvic locations.
Emerging techniques complement the diagnostic arsenal. One of them is an ultrasound technique that measures tissue stiffness (elastosonography), highlighting the fibrotic areas of deep endometriosis. PET-CT, which visualizes cellular activity using a weakly radioactive tracer, has confirmed lesions, although tracer uptake was inconsistent; new radiotracers such as 18F-fluoroestradiol are under investigation.
One limitation remains: no modality is 100% sensitive, and normal imaging does not rule out the diagnosis. Predictive value also depends on prevalence and on the size, location and depth of the lesions, which are rarely stratified in studies. It is therefore the expert integration of symptoms, clinical findings and imaging signs that guides decision-making.
Management: relieving symptoms, limiting recurrence, preserving fertility
There is no curative treatment. The strategy is individualized according to symptoms, patient preferences and pregnancy plans, which may change over time.
Pharmacological treatments
Nonsteroidal anti-inflammatory drugs are often offered, although evidence of their specific efficacy remains insufficient. The mainstay is hormonal therapy: combined contraceptive pills, preferably taken continuously to suppress menstruation, or progestin-only contraceptives. These treatments reduce pain to a clinically significant degree, with no clear superiority of one over another. As second-line options, drugs that put the ovaries at rest (GnRH agonists and antagonists) are combined with a low-dose compensatory hormonal supplement to protect bone; drugs that block estrogen production (aromatase inhibitors) are reserved for forms resistant to other treatments. Nevertheless, 11% to 19% of patients do not respond, and 25% to 34% see their pain return within a year of stopping treatment.
Surgery
Laparoscopy remains the reference surgical approach, both diagnostic and therapeutic, when medical treatment is ineffective, contraindicated or poorly tolerated. For endometriomas, cystectomy offers a lower recurrence rate than drainage or ablation (approximately 9% vs 37%), at the cost of a roughly 38% decrease in anti-Müllerian hormone (AMH), a marker of ovarian reserve. Deep endometriosis involving the bowel or urinary tract requires experienced multidisciplinary teams because of the risk of complications. Above all, surgery is not curative: symptoms recur in 40% to 45% of patients, and up to 30% undergo repeat surgery within five years. Postoperative hormonal treatment markedly reduces this risk.
Complementary approaches. Pelvic floor rehabilitation, psychological support, mindfulness, physical activity and dietary changes are being evaluated in clinical trials. Care involving several professionals is essential, particularly when pain is sustained by the nervous system itself.
Conclusion: earlier diagnosis, personalized management
Endometriosis is not a single disease but a spectrum of presentations with diverse mechanisms. Its management has changed profoundly: diagnosis no longer systematically requires surgery, and imaging, led by transvaginal ultrasound and MRI, is emerging as the cornerstone of earlier non-invasive diagnosis. Nevertheless, negative imaging should never end the diagnostic process when the clinical picture is suggestive.
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