Before we do what you came here for and demystify endometriosis stages, let’s just take a moment to acknowledge that this condition can make your life hell in a lot of ways. Perhaps you spent countless hours in doctor’s offices before getting a diagnosis, shelling out for appointment fees even though you usually left with more questions than answers. Maybe even now that you know you have endometriosis and are trying to treat it, you’re still wracked with excruciating pain every time your period rolls around. But even some people who have dealt with this condition for years don’t know about endometriosis stages and what they might mean.
Here’s a look at what endometriosis is to begin with (since there’s still some confusion), how each stage may differ from the next, and what that can mean for treatment.
The basics of endometriosis
Anyone who’s heard even a bit about endometriosis has probably learned that the disease happens when tissue from the uterine lining (also known as the endometrium, or the stuff you shed when you have your period) grows outside of the uterus, usually elsewhere in the pelvis.
But many experts now describe the cause of endometriosis as wayward “endometrial-like tissue” because it can be genetically and hormonally different than the tissue found in the endometrium, Tamer Seckin, M.D., founder of the Seckin Endometriosis Center in New York City and co-founder of the Endometriosis Foundation of America, tells SELF. If this piques your interest, here’s a SELF investigation on the subject.
No matter exactly what this tissue is, its hormone-sensitive and inflammatory nature means it can lead to a host of problems including scar tissue, organ dysfunction that causes infertility, and, of course, pain.
Most of the time, endometriosis is diagnosed through laparoscopic surgery, which uses a thin, lit tube inserted through small abdominal incisions to view the internal organs, according to the American College of Obstetricians and Gynecologists (ACOG). Even with treatment like laparoscopic excision of endo lesions, endometriosis symptoms can linger.
The stages of endometriosis
There are a couple of different ways experts stage or categorize endometriosis during diagnosis or excision.
The American Society for Reproductive Medicine (ASRM), which offers the most widely used endometriosis classification system, segments the disease into four distinct stages. These stages quantify how much endometriosis is present and how much anatomical distortion the disease has caused, Mark Hornstein, M.D., director of the reproductive endocrinology division at Brigham and Women’s Hospital and a professor at Harvard Medical School, tells SELF.
More or less, by knowing the stage of disease you have per this classification system, you and your doctor know how much the disease has impacted your body, how big your endometriosis lesions are, and the extent of scar tissue your endometriosis has caused.
The ASRM’s staging protocol is based on a point system. The more advanced your endometriosis per this system, the more points you’ll have:
- Stage I (1 to 5 points): This is known as minimal disease, meaning there are a few spots of surface-level endometrial-like tissue outside of the uterus.
- Stage II (6 to 15 points): Also known as mild disease, this is categorized by an increased amount of deeper lesions.
- Stage III (16 to 40 points): This stage, otherwise known as moderate disease, includes a mix of multiple deep endometriosis lesions, small endometriomas (endometriosis-induced ovarian cysts), as well as scar tissue (also called filmy adhesions).
- Stage IV (>40 points): With severe disease, you’d have many deep endo implants as well as significant scarring and large cysts on one or both ovaries.
- Category I: This is known as peritoneal endometriosis. It describes endometriosis that impacts the peritoneum (the fancy name for the membrane encasing your abdominal wall and most of your abdominal organs), but not in a deep and pervasive way. This is the first category because endometriosis often involves the peritoneum as a baseline characteristic.
- Category II: This stage is marked by those ovarian endometriomas we mentioned above, which are also called chocolate cysts because they’re full of old blood.
- Category III: The Endometriosis Foundation of America describes this as deep infiltrating endometriosis I (DIE I). It means that endometriosis lesions have seeped more than 5 millimeters into peritoneal tissue on pelvic organs, Dr. Seckin explains. “The concept of deep endometriosis is clinically significant because of the major operational requirements it may call for,” says Dr. Seckin.
- Category IV: Also known as deep infiltrating endometriosis II (DIE II), this most severe stage involves organs inside the pelvic cavity, like the appendix, along with some outside of it, like the lungs.
The biggest problem with trying to stage or categorize endometriosis is that the extent of the disease doesn’t necessarily correlate with pain, the most notorious endo calling card. “Individuals may have high-stage disease but low pain levels, and often we see individuals with low-stage disease who have severe pain,” says Dr. Hornstein.
Endometriosis lesions of any size can release varying levels of prostaglandins or cytokines (chemicals associated with pain), Dr. Hornstein says. These lesions can also have different colors, which may influence pain. They may be black, blue, clear, or red, for example, and it’s been suggested that clear or red lesions secrete more pain-related compounds, says Dr. Hornstein.
One other drawback of these endo classification systems is that they don’t totally indicate how endometriosis may impact fertility. There could be some correlation, of course, between more severe endometriosis stages and lowered chances of fertility, but it’s not a perfect science. The endometriosis fertility index (EFI) is a numbered scoring system that’s meant to be an answer to this problem. “It’s practical in estimating a woman’s chances for pregnancy,” says Dr. Seckin.
According to the Merck Manual, the EFI works to predict pregnancy odds by using factors such as:
- Your ASRM endometriosis stage
- Your age
- The amount of time you’ve been unable to conceive
- Any prior pregnancies you’ve had
- A “least function score” that describes how organs like your fallopian tubes, fimbria (the small, fingerlike projections at the end of your fallopian tubes), and ovaries seem to be working
“Overall, if the [ovaries], tubes, and fimbria look normal, the score is graded higher than six, and the outlook is positive for pregnancy,” says Dr. Seckin. “If the score is less than five, the outlook is not as good.”
Is endometriosis ever treated depending on its stage?
In short: It depends.
Doctors will only know what stage of endometriosis you have if you get laparoscopic surgery. As you may have experienced, people don’t always get laparoscopies before an endometriosis diagnosis. Sometimes, doctors are instead making an extremely educated guess based on a person’s symptoms. That would automatically mean they can’t treat you by stage, which can actually still work out OK. As Kristin Patzkowsky, M.D., assistant program director of the ob/gyn residency program at Johns Hopkins Hospital, puts it: If you’re doubled over in pain, does it matter if you have two tiny lesions or widespread scar tissue throughout your pelvic region?
To that end, doctors often treat endometriosis based on what brought a patient into their office. “If a woman has pain, then I’ll treat because she has pain,” says Dr. Hornstein. “If she’s trying to get pregnant, in general, one would help her get pregnant.”
First-line medications for endometriosis pain include nonsteroidal anti-inflammatory drugs (NSAIDs) along with hormonal therapy like birth control pills or IUDs, according to the Mayo Clinic. Hormonal therapy that contains estrogen (like combination birth control pills) can help stabilize hormone fluctuations and suppress ovulation, which can reduce how much endometriosis lesions bleed and cause pain. And hormonal therapy methods that have progestin (like all birth control pills and some IUDs) can thin the uterine lining so your periods aren’t as heavy or agonizing. Then there are still other forms of hormonal therapy, like elagolix, an oral gonadotropin-releasing hormone (Gn-RH) antagonist that’s FDA-approved to treat moderate to severe endo pain. That Gn-RH antagonist bit is a mouthful, but it essentially means elagolix lowers levels of hormones like estrogen that contribute to endometriosis. For people who are experiencing fertility problems due to endometriosis, doctors may recommend drugs to increase ovulation, according to the Mayo Clinic.
But sometimes these types of measures aren’t enough. “[Hormonal therapy can stop] ovulation and manage pain, but it doesn’t treat or eliminate endometriosis,” says Dr. Seckin. Or maybe your doctor thinks medications aren’t going to be sufficient to help you conceive.
Laparoscopic surgery to excise those troublesome lesions can help in these situations, and knowing the stage of endometriosis someone has may allow a surgeon to be more effective. Every single lesion can be a component of a person’s pain, Dr. Seckin says. “Like pixels of a TV screen, you need to really go after every small lesion,” he explains. This type of surgery can also target cysts and scar tissue. As another example, your endometriosis fertility index score could help you and your doctors decide whether or not to consider fertility treatments such as in vitro fertilization (IVF).
Ultimately, though, “[endometriosis staging] doesn’t matter so much from a patient perspective,” Dr. Patzkowsky says.
What does matter? Your lived experience with endometriosis, says Dr. Hornstein. Advocating for yourself as a patient can be exhausting (especially on top of dealing with a condition like endometriosis), but if your symptoms are too much to deal with, it’s important to seek answers about the best course of action for you.