The Asymmetry Distribution of Endometriotic Lesions: Italian Multicenter Study (NICCHIENDO)

The Asymmetry of Endometriotic Lesions as Demonstration of the Theory of Menstrual Reflux and Anatomical Niches: Italian Multicenter Study by the ETIC Group

This study aims to understand whether endometriosis lesions - and tumors that can arise in association with endometriosis - occur more often on one side of the pelvis than the other.

During surgery, doctors will record the exact location of each lesion to see if there is a consistent right- or left-sided pattern.

Understanding these patterns may help improve knowledge about how endometriosis develops (pathogenesis), and thus improve its treatment.

Study Overview

• Status: Completed
• Conditions: Endometriosis; Analyze the Laterality of Endometriotic Lesions and Endometriosis-related Tumors
• Intervention / Treatment: Procedure: surgery

• Study Type: Observational
• Enrollment (Actual): 2000

Contacts and Locations

Study Locations

• Italy
  • Milan, Italy, 20122
    • Gynecology Unit, IRCCS Fondazione Ca' Granda Ospedale Maggiore Policlinico, Milan

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

All patients with histological diagnosis of endometriosis and endometriosis associated with endometrioid carcinoma, clear cell carcinoma and seromucinous borderline tumor operated at the Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and at the centers participating in the study from 01/2013 to 12/2023 will be recruited.

Data relating to histological diagnosis will be collected from medical records.

In particular, in addition to tumours associated with endometriosis, data will be collected from patients with a histological diagnosis of:

1. ovarian endometriosis
2. intestinal endometriosis
3. ureteral endometriosis
4. sciatic nerve endometriosis
5. inguinal-round ligament endometriosis
6. uterosacral ligament endometriosis
7. peritoneal endometriosis
8. diaphragmatic endometriosis
9. pleural and pulmonary endometriosis
10. umbilical endometriosis (associated with right hemidiaphragm and/or left hemidiaphragm)

Description

Inclusion Criteria:

• age ≥18 years at the time of histological diagnosis of endometriosis
• patients undergoing surgery with endometriotic lesions or patients with endometriotic lesions associated with endometrioid or clear cell ovarian cancer (Stage I-II) or borderline seromucinous ovarian cancer
• first operation for endometriosis in the reference center (if recurrence consider only if both operations were performed at the reference center).

Exclusion Criteria:

• age <18 years
• patients affected by Stage I-II endometrioid or clear cell carcinoma or seromucinous borderline ovarian cancer not associated with endometriosis or in a more advanced stage of disease
• women with an ultrasound diagnosis of endometriosis who have not undergone surgery
• previous operations for endometriosis performed at another center

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Asymmetric distribution of endometriotic lesions on paired pelvic organs	Proportion of patients presenting an asymmetric (right- or left-sided) distribution of endometriotic lesions on even and symmetrical pelvic organs (e.g., ovaries, uterosacral ligaments), based on the laterality observed and described during the index surgical procedure. Side-specific frequencies (right vs left) will be reported as number and percentage.	At the time of index surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Asymmetric distribution of malignant ovarian lesions related to endometriosis	Proportion of patients presenting an asymmetric (right- or left-sided) distribution of malignant lesions related to endometriosis-specifically endometrioid ovarian carcinoma, clear cell ovarian carcinoma, and seromucinous borderline tumors-based on the laterality observed and described during the index surgical procedure. Side-specific frequencies (right vs left) will be reported as number and percentage.	At the time of index surgery

Collaborators and Investigators

• Sponsor: Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2024
• Primary Completion (Actual): May 1, 2025
• Study Completion (Actual): July 1, 2025

Study Registration Dates

• First Submitted: August 19, 2024
• First Submitted That Met QC Criteria: December 12, 2025
• First Posted (Actual): December 26, 2025

Study Record Updates

• Last Update Posted (Actual): December 26, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: October 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Genital Diseases, Female; Endometriosis; Surgical Procedures, Operative
• Other Study ID Numbers: 0029787 U; NICCHIENDO (Other Identifier: IRCCS Fondazione Ca' Granda, Ospedale Maggiore, Policlinico, Milan)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No