Several classifications exist to describe peri-operative complications including the Clavien-Dindo classification which is easily applicable to laparoscopic removal of endometriosis in all stages and is widely recommended for the evaluation of outcomes of endometriosis surgery. The most widely used staging system is the one reviewed by the American Society of Reproductive Medicine (rASRM) which, however, does not study DIE. In contrast, the ENZIAN score studies the anterior, posterior and lateral compartment of the pelvis and provides more reliable information on the extent of lesions. On the other hand, the rASRM and ENZIAN classification systems expressing the disease burden only indirectly correlate with the risk of postoperative complications and are not good predictors of post-surgical complications [19].

There are no studies in the literature evaluating the association of these complications with aspects such as the technical difficulty of surgical removal of endometriosis in relation to the extent of the disease.

The study of perioperative complications is essential in endometriosis surgery, so having a classification system capable of predicting complications on the basis of surgical complexity could guide clinical practice and post-operative management of patients with DIE.

This study could provide useful elements not only to improve the post-operative outcome of the operated patients, but also to identify preoperatively those pictures of DIE for which the surgeon will have to pay more attention because they have a higher risk of perioperative adverse events.

Endometriosis is a benign chronic inflammatory disease associated with pelvic pain and subfertility, characterised by endometrial tissue located outside the uterus. Deep endometriosis (deep infiltrating endometriosis, DIE), the most severe form of endometriosis, can be defined as the involvement of anatomical organs and tissues by endometriotic lesions, regardless of the depth of infiltration.

The first therapeutic approach for deep endometriosis is hormone therapy; surgery should be limited to patients who have not responded or have intolerance to medical therapy, infertile patients with failed attempts at assisted reproductive technologies, or patients with critical ureteral or intestinal stenosis. Although complete removal of the disease has proven effective in reducing pain and improving fertility results, surgical complications can occur in 3% to 22% of cases and can drastically reduce patients' quality of life.

Several intraoperative staging systems for endometriosis have been proposed. However, there is a lack of a scoring system that accurately describes the disease burden. Recently, the American Association of Gynecologic Laparoscopists (AAGL) has developed and validated an anatomy-based grading system for intraoperative scoring of surgical complexity, using a qualitative index scale as a reference that identifies a score and also allows the assignment of a surgical complexity stage.

There are no studies in the literature evaluating the association of these complications with aspects such as the technical difficulty of surgical removal of endometriosis in relation to the extent of the disease. The study of perioperative complications is imperative in endometriosis surgery, so having a classification system capable of predicting complications on the basis of surgical complexity could guide clinical practice and post-operative management of patients with DIE.

This study could provide useful elements not only to improve the post-operative outcome of operated patients but also to identify preoperatively those DIE pictures for which the surgeon will have to pay more attention because they have a higher risk of perioperative adverse events.

Inclusion Criteria:

• 18 years to 55 years;
• Pelvic ultrasound and/or radiological (MRI/ CT scan with rectal insufflation) diagnosis of endometriosis and surgery;
• At least 90 days of follow-up after surgery;
• Acquisition of informed consent for participation in the study and processing of data

Exclusion Criteria:

• Gynaecological oncology;
• Incomplete resection of macroscopic endometriotic lesions

Women of childbearing age with endometriosis undergoing complete laparoscopic removal of endometriotic lesions between January 2018 and December 2023 consecutively