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Classification of Endometriosis Question: Dr. Cook, can you please explain the endometriosis classification system? Answer: Sure, but first, let's clear up some terminology. The word classification is defined as an "arrangement according to some systematic division into classes or groups." Stage is defined as "the level or degree in a process of development, growth or change.” The purpose of a classification system is to identify the relative severity of a disease process. The more severe the disease, the greater the health risk to the patient. Mild disease would be less serious than severe disease. When used in staging cancer, the ramifications of increasing disease severity are obvious: The more severe the stage, the more likely that the disease has spread, and the less likely the patient will survive. The endometriosis classification system contains four stages (Stage I, Stage II, Stage III, and Stage IV) of disease severity. Endometriosis is not a cancer, and it does not threaten your physical survival. But those of you who have personally dealt with endometriosis (either yourself or others in your life) understand the toll it can take in so many different ways. Women with endometriosis experience two primary problems: infertility and pelvic pain. An ideal endometriosis classification system would determine the severity of the disease, based upon the degree of infertility or pelvic pain, and would predict the probability of success of any given treatment. The difficulty arises in the fact that we, as a medical profession, do not have a sufficient level of understanding of this disease to know how to measure these parameters. If we knew exactly how endometriosis affected fertility, then we could create a test that would measure the amount of such a change. The same goal applies to endometriosis-related pelvic pain: This approach would determine the severity of endometriosis as it relates to infertility or pelvic pain. The current classification system was created with the goal of predicting a patient’s future fertility, based on the stage of her endometriosis. Unfortunately, at this time the current endometriosis classification system does not predict a woman's chance of pregnancy. Additionally, this classification system was not intended to, nor is it successful in, predicting the amount of pain a woman experiences. Finally, it does not predict the chance of pain relief following treatment. History of the Endometriosis Classification System During the 1970s multiple endometriosis classification systems were proposed, leading to confusion and a lack of consensus. This prompted the American Fertility Society (AFS) to appoint a committee with representatives from many of the previous classification systems, with the intent of creating a uniformly acceptable endometriosis classification system. The original AFS classification system was published in 1979. The stated goal of this system was to predict the chance of conception (pregnancy) after the treatment of endometriosis. But this system was never intended to predict the amount of pain a patient experienced as a result of endometriosis, nor the chance of pain relief after treatment for endometriosis. The AFS classification system used a point system for staging endometriosis. A certain number of points were assigned in various categories. These included the size and depth of endometriosis present on the ovaries and peritoneum, amount of scar tissue around the ovaries and fallopian tubes and if there is obliteration of the cul-de-sac. The cumulative number of points determined the stage (mild, moderate, severe, or extensive) of endometriosis. In the early 1980s, Dr. John Rock and his colleagues published a couple of studies that evaluated the AFS classification system, which they felt presented two major limitations: First, they were concerned that the weighting of the various categories did not correctly reflect the impact of endometriosis on fertility. Second, the cutoff points of the total AFS score for each stage were arbitrarily assigned. Rock and his colleagues felt that these factors limited the ability of the AFS classification system to predict the chance of pregnancy after the treatment of endometriosis. The revised AFS (R-AFS) classification was approved in 1985, and included changes that attempted to correct the limitations of the initial classification system. This is a more detailed system that recognized the difference between superficial and invasive disease, and changed the terminology of the four stages to minimal, mild, moderate and severe. In 1995 the American Fertility Society was renamed the American Society for Reproductive Medicine (ASRM). The ASRM's Endometriosis Classification for Infertility Subcommittee collected data from several centers to evaluate the R-AFS classification system and pregnancy rates, and published their study in the May 1997 issue of Fertility and Sterility. The authors concluded that there was no correlation between the stages of endometriosis, as determined by the R-AFS classification system, and pregnancy rates. The last sentence of the article states, "At the very least, our results suggest that fine-grained distinctions between patients with respect to point scores, although useful for documentation, are not clinically useful with respect to the prognosis" (chance of pregnancy). At the same time there was data accumulating that suggested that the appearance of endometrial implants might correlate with their biologic activity, and thus, pregnancy rates. An additional recommendation to record the appearance of endometrial implants was made in 1996. Current Endometriosis Classification System Figure 1. Revised American Society for Reproductive Medicine Classification System: 1996 Reprinted by permission from the American Society for Reproductive Medicine (Fertility and Sterility, 1997, Vol. 67, No. 5, Page 819) Figure 2. Examples and Guidelines for the R-ASRM 1996 Endometriosis Classification System: Reprinted by permission from the American Society for Reproductive Medicine (Fertility and Sterility, 1997, Vol. 67, No. 5, Page 820) This classification system is basically the R-AFS system based upon the size, location, depth of invasion of endometrial implants, and the amount of scar tissue involving the ovaries and fallopian tubes. In addition, the appearance of the endometrial implants is classified as red, white and black. The red lesion category includes red, red-pink and clear lesions. The white lesion category includes white, peritoneal defect, and yellow-brown lesions. The black lesion category includes both black and blue lesions. Perhaps, the addition of the physical appearance of the endometriotic lesions will help improve the accuracy of the classification system in predicting the chance of pregnancy following treatment of endometriosis. Still, the classification system does not apply to patients with endometriosis-related pain. As the mechanisms by which endometriosis causes infertility and pain are better understood, a more refined and useful classification system will be possible. Until that time, the classification system provides a means to concisely document the surgical findings. For all patients who are undergoing laparoscopic evaluation and treatment, a videotape of the surgery should be included as a part of their medical record to provide the most accurate findings. This will allow for the "re-staging" of a patient's endometriosis as the current classification system is refined, and future classification systems are created. |
