Leeches: so common a tool in medical history that for part of the 1800's, France was importing about 33 million leeches annually. With so many to keep track of, one journal advised doctors to count their leeches before and after a bloodletting for gynecological conditions — because a leech lost in a woman's uterus would cause not only extreme physical pain but also undue mental stress.

Yes, you read that correctly. Internal bloodletting. Leeches up the vagina. Aren't you glad to live in the 21st century?

By now, modern medicine understands that endometriosis is an extremely painful gynecological condition where cells from the endometrium — that is, the innermost layer of the uterus — show up elsewhere in the body. These growths of endometrial cells, also called ectopic lesions, cause infertility in affected women as well as inflammation and scar tissue wherever they grow. That scar tissue can turn into adhesions, sticking abdominal organs together (ow). This condition affects about one in ten women, which means a conservative estimate would be over 15 million people suffering from endometriosis in the United States alone. The only sure diagnosis is through laparoscopic surgery (inserting a camera to get a clear view of the lesions), and the only current treatment of the root cause (the lesions) is through surgery (deep tissue excision or total hysterectomy, which doesn't always help). Symptoms can be treated with painkillers and hormone therapy, but that's the same broad treatment for most gynecological conditions. Even with so many women affected, progress in understanding this disease has been slow.

A basic description of endometriosis was first given around the fifth century B.C.

The writers of the Hippocratic Corpus, of the fourth and fifth centuries B.C., narrowed down the symptoms of a gynecological disease to four main factors: pain, infertility, menstrual dysfunction and temporary relief with pregnancy. Although there was some suggestion that social class may influence the condition (that it was somehow only a condition of the upper class), these four symptoms would form a common thread connecting various seemingly distinct conditions with various names that wouldn't be connected in the medical field for thousands of years. Though we now refer to the condition as endometriosis, its most popular name for centuries was "suffocation of the womb" first coined by the Greek philosopher Plato (375 B.C.). According to him, this suffocation occurs because a uterus left too long without pregnancy starts to wander around the young woman's body, hungry for motherhood. If it wanders too far, the tubes get tangled and it is unable to breathe. Women so afflicted in ancient Greece would be treated with succession, the practice of tying the patient upside down on a ladder and shaking them until the womb returns to its proper location. The best prevention method they could come up with was to have girls get married and pregnant as soon as possible after puberty so as to satisfy this hungry and animalistic organ. This method of thinking about gynecological conditions likely contributed to the culture of early marriage for women throughout history and is actually still used in some parts of the world.

After about 500 years of descriptions of extreme pelvic pain causing convulsive fits, persistent infertility, organ adhesions and ligaments infiltrated with endometrial tissue, in the second century A.D., Galen of Pergamon concluded that on one hand, suffocation of the womb might be caused by menstrual blood flowing backwards and becoming anchored in the wrong organs (a theory still used today, called retrograde menstruation theory), and on the other hand, the condition is also likely psychological in nature because young widows simply must go mad after "their loss of sexual fulfillment."

Given centuries of medical research on this kind of pain... Meh, it's all in her head.

This was the first time that gynepathology was authoritatively linked with psychology (though the Hippocratic Corpus also vaguely suggested a link), and it was far from the last. From this seed of thought, the idea that women in chronic, invisible pain are just crazy would persist for millennia. Women would be labeled hysterical, blamed for their conditions, locked in madhouses that civilians visited for entertainment, and treated with shock therapy.

But that's up to the 19th century — let's not get ahead of ourselves. We wouldn't want to miss witchcraft and demonic possession, right?

She's a witch, and she's a witch, and she's a witch...

During the Middle Ages — or the Dark Ages of Europe — the supernatural found its way into the scientific scene. Whether a convulsive fit of pain was blamed on the woman herself being possessed, who was then exorcised, or was blamed on the neighbor across the street, who was then sent to the pillory or executed on charges of witchcraft, women got the worst of this new companionship between the mystic and the medical. Despite new observations on the anatomy of suffocation of the womb, such as an association with ulcers, treatments developed during the Middle Ages included those such as "shouting therapy" and other painful or torturous prescriptions with the idea that a malady like invisible pelvic pain is caused somehow by the woman's bad behavior, so the treatment must be karmic in response. We have to look elsewhere in the world for a bit of level-headedness. For example, it was Avicenna, the Persian polymath, who finally determined that pain was solely biologic and had zero medical benefits. Yet, with no cause of the chronic pelvic pain in sight, ideas of demons and magic as a cause of suffocation of the womb persisted through the Middle Ages and into the Renaissance. Occasionally, a physician would be called in as a witness during witchcraft trials, and it's known that Dutch physician Johannes Weyer and English physician Edward Jorden defended the women accused of witchcraft, insisting that the allegedly supernatural symptoms were in fact entirely natural conditions of the uterus.

The women were found guilty.

Women like them were found to be witches while, at the same time, physicians searched for a medically treatable cause of their ailment. There were two paths of research happening in parallel — some physicians, such as Thomas Sydenham, began to flesh out theories of a psychological cause of "hysteria," while others, like William Harvey and Johannes Vesling, looked to autopsies for a physical source of suffocation of the womb. Both of these paths would develop into the 20th century, and it appears that the treatment a woman got depended on whether she was recommended to a physician or a psychologist for her symptoms.

Physicians and psychologists gave wildly different treatments, but both would appear to have hundreds of years of research backing up their conclusions.

Women diagnosed with hysteria were held in the worst of mental institutions, including the infamous St. Bethlehem Hospital (commonly known as Bedlam), where they were physically restrained with chains and straitjackets. In France, many were held at Salpêtrière outside of Paris. The "hystero-epileptic" ward was entirely comprised of young women, the vast majority complaining of ovarian pain, yet even when the famous French psychiatrist Jean-Martin Charcot visited and made note of this common thread that should have pointed to a gynapathological condition, he concluded that the condition was psychiatric in nature. There was no reason, it seemed, to stop sending these "hysterical" women to the worst of prisons: mental institutions of the 19th century.

Meanwhile, physical signs of endometriosis were noticed most clearly in 1852 by Edward Tilt and in 1858 by Armand Trousseau, who identified the lesions on a macroscopic scale, and named the disease "catamenial hematoceles." It was finally in 1860 that Karl von Rokitansky discovered microscopic signs of endometriosis. Looking at strange tissue growths and uterine polyps, he noticed striking similarities between the growths and the characteristics of endometrial tissue, specifically the presence of glands that should only be present on the tissue inside of the uterus. These findings would be confirmed (or re-discovered) in 1921 by John Sampson, who would then coin the term "endometriosis" in 1927. Importantly, in 1887, Franz Wickel was the first to realize that it was women with very small endometriotic lesions who were most likely to be diagnosed with hysteria and sent to mental institutions, as the lesions were virtually undetectable.

20th century progress (mostly).

In the 1900's, a woman with pelvic pain but no clear cause could still be referred to psychiatrists, but progress in treatment and public awareness was rapidly increasing. Hysterectomy and specific nodule removal surgeries became more advanced with the introduction of non-video laparoscopy in the 1940's. In the 1950's, pelvic exams, previously considered a vulgar suggestion in the United States, became a common procedure with the rising awareness of cervical cancer and the introduction of the Pap smear. It was also in the 1950's that, with the vision of Margaret Sanger, the funding of Katharine McCormick, and the science of George Pinkus that the hormonal contraceptive pill was first introduced, and women with endometriosis were some of its earliest recipients. Unfortunately, the pill at that time used such high doses of estrogen that its side effects included cancers. Research didn't always move forward, though. In 1949, an investigator brought back theories from ancient Greece when he asked, "Is endometriosis principally a disease of the higher social and economic levels of society?"

Video-assisted laparoscopy was developed in the 1970's, and over time the cameras became smaller and the surgeries more precise. While surgical precision and awareness of rampant misdiagnosis have increased in the last few decades, there is still much confusion over the best treatment options for endometriosis. With only laparoscopy as a diagnostic, there is an average of seven years between the onset of symptoms and a diagnosis of the condition. Treatments now include full hysterectomy, deep tissue excision and hormone treatments — none of which tend to work on the first try. This leads women to get multiple surgeries in attempts to treat their chronic pain. Even as recently as 1995, reports have shown that over 50 percent of women complaining of chronic pelvic pain were told there was no "organic" basis for their complaints, thus leaving them forever untreated, or labeling them mentally unstable, or they're even recommended pregnancy as a treatment — the same archaic conclusion as thousands of years ago.

After thousands of years of ambiguity and belittling, it's clear that more information is needed about endometriosis.

Frustratingly, some recent researchers purport to quantify the relative attractiveness of women with endometriosis, or characterize personality traits of women with pelvic pain.

However, many researchers are taking steps in useful, foundational research, working out the molecular markers of the condition, some of which might be treatable with prescription drugs or be useful as a diagnostic red flag as an alternative to laparoscopy.