Endometriosis Classifications – rASRM, ENZIAN and #ENZIAN

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;

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. [1]

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 [4], 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. [2] 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.