Researchers from the Ashford and St. Peter’s Hospitals NHS Foundation Trust have been working on a new classification system that accurately describes the extent and severity of endometriosis, particularly intraoperative findings, and is inviting endometriosis surgeons to join them in further refining the system.

A small review of the currently used classification systems and a description of the novel system, Visual Numeric Endometriosis Surgical Stating (VNESS), have been published in the Journal of Reproduction and Infertility in the study, “Endometriosis Classification – The Quest for the Holy Grail?”

Endometriosis is a disease that affects approximately 6–10 percent of women worldwide, characterized by growth of the endometrium outside the uterus, which leads to infertility and pain. Although important advances have been made in recent decades, lack of a widely accepted and accurate classification system has hampered a greater evolution and a better understanding of the disease.

To date, a number of systems that aim at classifying or staging endometriosis have been proposed. However, endometriosis is a complex disease and it is difficult to develop a system that describes the surgical findings, correlating them with symptoms and predicting fertility outcomes.

The revised American Society for Reproductive Medicine (rASRM) is now the most commonly used system. But it is widely criticized by physicians because of its lack of correlation with symptoms, poor reproducibility, and arbitrary point system.

Another system that attempted to address some of rASRM’s problems, the Enzian system, was too complex and failed to gain wide acceptance. Endometriosis Fertility Index (EFI) is the only system validated to predict surgical outcomes and has shown promising results in pregnancy prediction. Although EFI is not able to measure surgical complexity or to correlate with symptoms, its success is mostly derived from the fact that it does not try to solve all problems at the same time.

Led by Dr. Shaheen Khazali, the team has been developing a system for the past two years that limits to describing the surgical findings, but does not attempt to correlate them with fertility outcomes or symptoms. VNESS uses eight numbers that correspond to a specific compartment in the pelvis to help the surgeons describe the surgical findings. In each compartment, the disease severity is evaluated from 0 (no disease) to 4 (visceral invasion).  To assist VNESS in measuring the surgical outcome and complication rates, a “complexity score” ranging from 0 to 10 is employed.

Since endometriosis is of highly complex nature, trying to address surgical findings, predict surgical outcome, fertility outcomes, and correlate the disease staging with symptoms all in one classification system may not be feasible. A classification system may be easily accepted when designed for simplicity, practicality and flexibility, and the solution might be on addressing one problem at a time.

The researchers are forming an international collaborative group to redefine VNESS, and invites endometriosis surgeons to join them.