The Asymmetry Distribution of Endometriotic Lesions: Italian Multicenter Study

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.

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Key information

Conditions

Analyze the Laterality of Endometriotic Lesions and Endometriosis-related Tumors Endometriosis Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Genital Diseases Genital Diseases, Female Urogenital Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Observational

Primary location

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

Milan, 20122, Italy

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Surgery

Procedure

All patients enrolled in the study underwent surgery for endometriosis between 2013 and 2023.

Primary outcomes

Asymmetric distribution of endometriotic lesions on paired pelvic organs

Time frame: At the time of index surgery

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.

Secondary outcomes

Asymmetric distribution of malignant ovarian lesions related to endometriosis

Time frame: At the time of index surgery

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.

Sponsors and collaborators

Lead sponsor

Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico

Other

Registry information

Official study title

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

Acronym: NICCHIENDO

Important dates

Study start: 2024
Primary completion: 2025
Study completion: 2025
First posted: Dec 26, 2025
Registry last updated: Dec 26, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed