Endometriosis is a common, complex gynecological condition characterized by the presence of tissue similar to the lining of the uterus growing outside the uterine cavity. This misplaced tissue causes chronic inflammation, pain, and often leads to the formation of scar tissue and adhesions. The condition affects millions worldwide and has a long, confusing history of recognition. Its true nature remained obscured until significant advances in pathology and surgical technology occurred. The journey from recognizing the symptoms to formally identifying the disease spans centuries of medical observation and discovery.
Defining Endometriosis
Endometriosis is defined by the presence of endometrial-like glands and stroma located outside the uterus, most commonly in the pelvic cavity. This tissue is often found on organs such as the ovaries, fallopian tubes, and the lining of the pelvis (peritoneum). Unlike the normal endometrium, this misplaced tissue has no way to exit the body during menstruation, leading to internal bleeding, inflammation, and scarring. The condition is highly dependent on the hormone estrogen for its growth.
This chronic disease affects an estimated 10% of reproductive-age women globally, often causing debilitating symptoms. Primary complaints include severe pain during menstruation (dysmenorrhea), chronic pelvic pain, painful intercourse, and pain with bowel movements or urination. Approximately 30% to 50% of women with endometriosis also experience infertility.
Early Historical Descriptions
While the condition was not formally named until the 20th century, symptoms strongly suggestive of the disease have been documented for thousands of years. Ancient Egyptian papyrus documents contain references to menstrual pain and discomfort that align with modern descriptions. Similarly, Hippocratic physicians in ancient Greece described an endometriosis-like condition they termed “strangulation of the womb,” recognizing it as an organic disorder causing chronic pelvic pain.
In the absence of modern surgical or microscopic techniques, these historical accounts focused solely on external manifestations and symptom clusters. They were often vaguely attributed to general female ailments or “hysteria.” Physicians in the 17th and 18th centuries began documenting cases with lesions and cysts in the pelvic cavity, along with reports of heavy menstrual bleeding. These observations marked an important step toward recognizing a distinct disease entity separate from malignancies.
Formal Identification and Naming
The shift from describing symptoms to pathological identification began in the mid-19th century, driven by advancements in histology. The German pathologist Karl von Rokitansky is credited with the first microscopic description of ectopic endometrial tissue in 1860. Rokitansky identified endometrial glands and stroma outside the myometrial wall, though he initially mislabeled the finding as “cystosarcoma.”
In 1899, W.W. Russell published the first clear mention of an “ovary containing uterine mucosa,” furthering microscopic understanding. The microscopic features were defined more precisely in the early 1900s by Thomas Cullen, who described endometrial glands surrounded by mucosal stroma outside the uterine cavity.
The formal term “endometriosis” was coined by American gynecologist John A. Sampson, who used it in his publications around 1921 to 1925. Sampson systematically studied the condition, described its clinical manifestations, and proposed the theory of retrograde menstruation in 1927. This theory suggested that menstrual tissue flowed backward through the fallopian tubes to implant in the pelvis.
Evolution of Diagnostic Understanding
The 20th century brought a revolution in how endometriosis was diagnosed and visualized, moving past reliance on autopsy and major surgery. The introduction of laparoscopy in the early 1960s fundamentally changed the understanding of the disease, providing a minimally invasive way to visually identify and treat the lesions. Laparoscopy, which involves a small camera inserted into the abdomen, allowed clinicians to see the extent of the disease and confirm the diagnosis through targeted tissue biopsy. This ability to directly visualize the lesions led to a significant increase in diagnoses and a clearer picture of the disease’s prevalence.
Before laparoscopy, diagnosis often required a major abdominal operation or was only confirmed years later during a hysterectomy or autopsy. The new technology revealed a wide range of lesion appearances, from subtle white or red spots to the classic dark blue or black “powder burn” spots. The development of standardized classification systems, such as the revised American Fertility Society (AFS) staging in the 1970s and 1980s, helped categorize the disease based on the location, size, and depth of the implants. Although non-surgical methods like ultrasound and MRI are used, laparoscopy with biopsy remains the most accurate way to definitively diagnose endometriosis.