Endometriosis Classifications – rASRM, ENZIAN and #ENZIAN
Anyone who has ever had an endometriosis surgery report in their hand will come across these two classifications. At first glance, it may seem like a jumble of letters, but in just a few characters, it describes the location and extent of endometriosis found.
The revised American Society of Reproductive Medicine (rASRM) score is used to describe the location of endometriosis, but may not cover deeply infiltrating endometriosis comprehensively. For this purpose, the ENZIAN score is also utilized.
rASRM – Degree of Spread of Endometriosis
The rASRM score, developed by the American Society for Reproductive Medicine, is currently the most widely used classification system for endometriosis. According to guidelines by DGGG (Deutsche Gesellschaft für Gynäkologie und Geburtshilfe – German Society for Gynecology and Obstetrics), the rASRM score is recommended for every operation involving suspected endometriosis, making it an essential component of every operative report and doctor’s letter after an endometriosis procedure.
It primarily evaluates the extent of endometriosis spread to the ovaries and peritoneum. The peritoneum is the lining that covers the internal organs within the abdominal and pelvic cavity. The assessment also includes adhesions on the ovaries, fallopian tubes, and throughout the pelvic region. Points are assigned based on the degree of involvement, and the cumulative score determines the overall stage of endometriosis. This is used to determine the stage.
The stages are as follows:
|Stage I = rASRM I||1-5||Minimal Endometriosis|
|Stage II = rASRM II||6-15||Medium Endometriosis|
|StageIII = rASRM III||16-40||Moderate Endometriosis|
|Stage IV = rASRM IV||more than 40||Severe Endometriosis|
Accurate Calculation of the rASRM Score
Part I Endometriosis foci
|Localization||Depth||< 0,39 inch||0.39–1,18 inch||> 1,18 inch|
Part 2 Adhesions
|Obliteration (Occlusion due to Adhesions)
of the Douglas-Space
|Localization||Adhesion Consistency||< 1/3||1/3–2/3||> 2/3|
| depending on the size of the endometriosis lesions;
 with complete inclusion of the fimbriae-occupied end of the fallopian tube 16 points;
ENZIAN Classifies Deep Infiltrating Endometriosis
The ENZIAN classification accurately describes the location and size of deep infiltrating endometriosis. In contrast, the rASRM classification does not account for it. Large deep infiltrating foci, such as those growing in depth within the pelvic walls or on the bowel, do not result in a significant increase in the rASRM score, as it primarily measures size at the peritoneum. Therefore, the ENZIAN score complements the assessment by covering this aspect.
Depending on the specific location of deep infiltrating endometriosis, a letter combination is assigned in the ENZIAN classifications. For letters A to C there is an additional number describing the size. The detailed classification can be found in the tables and the figure.
|Localization||Septum rectovaginale = Between rectum and vagina/cervix||Deeply infiltrating into the lateral pelvic walls, lateral uterine ligaments, or around the ureter||deeply infiltrating the rectum / rectal cavity|
less than 0,39 inch
0,39 -1,18 inch
more than 1,18 inch
|FA||Adenomyosis – endometriosis in the uterus|
|FB||Endometriosis on the bladder|
|FU||Ureter intrinsic = growing into the ureter|
|FI||Other parts of the intestine except the rectum (rectum is classified as C). For example, small intestine, remaining colon or appendix.|
|FO||all other localizations (Other): Lung, Diaphragm, Brain, etc.|
The #ENZIAN classification has expanded beyond deep infiltrating endometriosis to encompass all areas and manifestations of endometriosis, allowing for a comprehensive description of the entire condition in one classification.
The original ENZIAN classification, which remains unchanged, includes the following letter and number combinations:
Letters A to C with additional numbers describing the size and localization.
The additional areas in the ENZIAN classification are as follows:
P – the peritoneum (the peritoneum): This can be classified as level P1 (under 3 cm), P2 (3-7 cm), or P3 (over 7 cm), based on the affected surface area. In the ENZIAN classification, “centimeter” refers to the diameter of a circle that can be placed over the endometriosis focus. For instance, an area as large as a 1 Euro coin would be classified as P1, and a focal area approximately as large as 5 cm in diameter would be categorized as P2.
O – the ovary (the ovary): Here, each side is designated individually as right or left, with divisions into O1, O2, and O3 based on the size of findings, determined by the diameter of the sum of endometriosis cysts on each side. “Om” indicates a missing ovary.
T – the tube/ tuboovarian complex (tube = fallopian tube, tuboovarian = at the fallopian tube and ovary): The letter T is used to describe adhesions or connections involving the fallopian tube/ovary caused by endometriosis lesion, which can affect their mobility and function. T1 denotes adhesions extending to the pelvic wall. In T2, the complex also “adheres” to the uterus, and in T3, additional structures like the intestine or the wider connective tissue, such as the uterosacral ligament, are involved. Each side is individually assessed and described as right or left.
Furthermore, under area T, one can describe fallopian tube patency testing. A positive tubal patency test is noted as T+, while a negative test for non-patency ovaries is described as T-.
Another notable innovation is the classification’s versatility, as it can be applied both during surgery and before surgery using ultrasound or MRI, indicated by small bracketed letters:
(u) – ultrasound
(s) – surgery
(m) – MRI
While not all areas may be fully visualized by ultrasound or MRI, any findings detected can now be accurately described in the #ENZIAN classification. In cases where an aspect cannot be assessed, it is marked with an (x), ensuring a comprehensive and precise classification of endometriosis findings.
An overview is available here;
What Is the Significance of the Classification – and What Is Not?
These two classifications serve as highly accurate tools for describing the surgical outcomes and anatomical spread of endometriosis. They are routinely used in operative reports, enabling other practitioners to quickly grasp the situation. The inclusion of these classifications is also mandatory for endometriosis center certification.
However, it is crucial to understand that the classifications provide a snapshot of the condition, and the situation may vary in subsequent operations. Additionally, there can be differences in assessments between surgeons. 
High Stage = Severe Pain?
One notable point to consider is that these classifications do not take into account the specific symptoms experienced by the individual. While statistically a higher rASRM / ENZIAN stage is associated with more severe pain on average , one cannot directly draw conclusions about symptoms based solely on the stage. Some women with endometriosis rASRM stage IV may experience no pain, while others with stage I can suffer from significant discomfort.
Stage and Fertility
Furthermore, fertility is not definitively considered in these scores. To assess fertility, fertility centers employ the endometriosis fertility index, which incorporates the rASRM and other scores, along with general factors like age and previous fertility problems. [2,3]
Stage and Prognosis
Experts also agree that these classifications say little about the prognosis of the disease or response to therapy.  Instead, factors such as the completeness of removal, prior symptoms, and other relevant factors play a more critical role in determining the outlook and response to treatment.
rASRM and ENZIAN are indeed essential and accurate scores for describing endometriosis, providing valuable insights into the anatomical spread and surgical outcomes. However, it is important to note that they offer indirect information on symptoms, therapy prognosis, and fertility. To obtain a comprehensive understanding of both superficial and, if present, deep infiltrating endometriosis, these scores should always be used together in combination.
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