Copenhagen, Denmark 19 - 22 June 2005

Recurrence rate of endometriosis decrease after vaginal delivery C Bulletti [1], D De Ziegler [3], M Stefanetti [1], M Balducci [1], C Flamigni [2] [1] Rimini’s General Hospital Physiopathology of Reproduction Rimini, Italy [2] University of Bologna Physiopathology of Reproduction Bologna, Italy [3] General Hospital Obstetrics and Gynecology Geneve, Switzerland

Introduction
Recurrence of endometriosis is due to an abnormal uterine contractility (UC) which produces a retrograde transport of endometrial debris into the pelvic cavity. Differences in time and frequency of recurrences are possibly related to both magnitude of UCs abnormalities and parity. Several studies reported data on UCs in non-pregnant uterus, while very few data are available in literature on the importance of the enlargement of internal os after vaginal delivery in relationship with recurrence of endometriosis. The present study is undertaken to establish the role of the size of internal os in determining recurrences of endometriosis.

Materials and methods
One hundred and eight women (age 21–37), with laparoscopical diagnosis of endometriosis (stage III-IV ASRM classification), were divided in two groups of 61 and 47 women according the diameter of internal measured by ultrasound (US): <5mm (group A) and >5mm (Group B). Dysmenorrhea (visual score: 1–10) and a second laparoscopy were used to detect the recurrence of endometriosis in 22 patients of group A and 36 patients of group B.

The laparoscopical and histological diagnosis of endometriotic implants in the pelvic cavity were used to establish the recurrence of the disease at any stage. Analysis of data was performed by using unpaired Student’s t-tests and linear regression analyses.

Results
Eight of 22 (36%) patients in group A had recurrence of the disease versus 31 of 36 (86%) in group B (p<0.002). When the entire sample of 58 patients who participated in at the study was analyzed, we found an inverse correlation from the recurrence rate of endometriosis and the size of internal os
(p<0.005).

Conclusions
The present study confirms the hypothesis that the displacement of uterine content into the pelvic cavity is the main cause of recurrence of endometriosis and emphasizes the role of the internal os in determining this recurrence. The internal os enlarges as recurrence rate of endometriosis decreases.

Enlargement of the diameter of internal os causes an increase of discharge endometrial debris into the vagina instead of into the abdomen through the tubes thus limiting the recurrence of the disease.

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