Endometriosis Fertility Index Calculations

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Endometriosis Fertility Index

David Adamson's Endometriosis Fertility Index (EFI) is a clinical tool used to predict pregnancy rates after endometriosis surgery. It is the only system that is predictive of fertility, but is not a staging system. The EFI has 6 levels and uses the 1985 American Fertility Society (rAFS) staging system’s total and endometriosis sub-total score separately. The EFI is based 50% on history, 30% on surgical findings at the completion of surgery, and 20% on the rAFS scores.

The 1984 rAFS staging system was renamed the revised American Society of Reproductive Medicine (rASRM) staging system in 1996 after that organization changed their name. The 1996 rASRM endometriosis staging system is the same as the 1984 rAFS endometriosis staging system with additional examples.

The rAFS is the staging system most commonly used at surgery but is not predictive of fertility. It can be used to describe the appearance at surgery and is somewhat predictive of surgical difficulty. The rAFS has 150 points. A score 40 or higher is rAFS stage 4. The rAFS separates stage 4 into scores for 4A (40 to 70 points) and 4B (71 to 150 points). Scores of 71 and higher are generally seen only with severe adhesions. Adhesions, a type of scar tissue, can block the pathway that the eggs use to get to the tube. Canis (1992) also uses the rAFS score of >70 to be stage 5 for endometriosis.

Adamson GD & Pasta DJ. Endometriosis fertility index: the new, validated endometriosis staging system. Fertil Steril 2010;94(5):1609–15

Endometriosis Fertility Index Calculations

Based on Figure 1 in Endometriosis Fertility Index.

(1) Calculate your historical factors score using the sum of the 3 historical factors.


  • Through age 35 years2 Points
  • 36 to 39 years1 Point
  • 40 years or older0 Points

Years of Infertility

  • Infertility up to 3 years2 Points
  • Infertility greater than 3 years0 Points

Prior Pregnancy

  • Yes1 Point
  • No0 Points

(2) Calculate your Surgical Factors score by comparing your understanding of your surgery to the following possibilities. If you have more than one answer, use both your highest and lowest estimates to see how those change the pregnancy rate projection on the Estimated Percent Pregnancy figure below.

  • Mild endometriosis and healthy tubes with no adhesions5 Points
  • Moderate endometriosis with healthy tubes and with all endometriosis and all adhesions removed4 Points
  • Moderate endometriosis with mildly damaged tubes and all endometriosis and adhesions removed3 Points
  • Severe endometriosis with healthy tubes, no large endometriomas, and all adhesions removed2 Points
  • Severe endometriosis with large endometriomas, mildly damaged tubes and most adhesions removed1 Point
  • Severe endometriosis, severe tubal damage and large endometriomas with many adhesions remaining0 Points

(3) Add the totals for your historical factors score and your surgical factors score for a total. Compare the total with the estimated percent pregnancy below. Note that high scores are good.

EFI Score Pregnant at 1 Year Pregnant at 3 Years
9-10 67% 75%
7-8 39% 66%
6 30% 54%
5 27% 42%
4 15% 28%
0-3 10% 10%

Adamson GD & Pasta DJ. Endometriosis fertility index: the new, validated endometriosis staging system. Fertil Steril 2010;94(5):1609–15

American Fertility Society. Revised American Fertility Society classification of endometriosis 1985. Fertil Steril 43(3):351-352, 1985

American Society for Reproductive Medicine classification of endometriosis: 1996. Fertil Steril 67(5): 817-21, 1997

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Updated February 20, 2020