Progression of deep infiltrating rectosigmoid endometriotic nodules

What is the risk of progression of deep endometriotic nodules infiltrating the rectosigmoid?

There is a risk of progression of deep endometriotic nodules infiltrating the rectosigmoid, particularly in menstruating women.

Currently, there is a lack of acceptance in the literature on the probability that deeply infiltrating rectosigmoid endometriotic nodules progress in size.

We conducted a monocentric case-control study between September 2016 and March 2018 at Rouen University Hospital. We enrolled 43 patients who were referred to our tertiary referral centre with deep endometriosis infiltrating the rectosigmoid, who had undergone two MRI examinations at least 12 months apart and had not undergone surgical treatment of rectosigmoid endometriosis during this interval.

MRI images were reinterpreted by a senior radiologist with experience and expertise in endometriosis, who measured the length and thickness of deep infiltrating colorectal lesions. Intra- and inter-observer reliability were tested on 30 randomly selected cases. We defined 'progression' of a nodule as an increase of ≥20% in length or in thickness and 'regression' of a lesion as a decrease of ≥20% in length or in thickness between two MRIs. Any nodule for which the variation in length and thickness was <20% was considered as 'stable'. Patients were divided into three groups based on evidence of progression, regression or stability of deep endometriotic nodules between their two MRI examinations. The total length of any period of amenorrhoea between the two MRI examinations, due to pregnancy, breastfeeding or hormonal treatment, was recorded. The total proportion of the time between MRIs where amenorrhoea occurred was compared between groups.

Eighty-six patients underwent at least two MRIs for deep endometriosis infiltrating the sigmoid or rectum between September 2016 and March 2018. Of these, we excluded 10 patients with an interval of <12 months between MRIs, 10 patients who underwent surgery between MRIs, 17 patients for whom at least 1 MRI was considered to be of poor quality and 6 patients for whom no deep colorectal lesion was found on repeat review of either MRI. This resulted in a total of 43 patients eligible for enrolment in the final analysis. Mean time (SD) between MRIs was 38.3 (22.1) months. About 60.5% of patients demonstrated stability of their colorectal lesions between the two MRIs, 27.9% of patients met the criteria for 'progression' of lesions and 11.6% met the criteria for 'regression' of lesions. There was no significant difference in time interval between MRIs for the three groups (P = 0.76). Median duration of amenorrhoea was significantly lower in women with progression of lesions (7.5 months) when compared to those with stability of lesions (8.5 months) or regression of lesions (21 months) (P < 0.001). Median duration of amenorrhoea (expressed as percentage of total time between two MRIs) was also found to be significantly lower in the group demonstrating progression (15.1%) when compared to the group demonstrating stability (19.2%) and the group demonstrating regression (94.1%; P = 0.006). Progression of rectosigmoid nodules was observed in 34% of patients without continuous amenorrhoea, in 39% who had never had amenorrhoea and in no patients with continuous amenorrhoea.

Due to a lack of universally accepted criteria for defining the progression or regression of deep endometriotic nodules on MRI, the values used in our study may be disputed. Due to the retrospective design of the study, there may be heterogeneity of interval between MRIs, MRI techniques used, reason for amenorrhoea and duration of amenorrhoea. The mean inter-MRI interval was of short duration and varied between patients. Our findings are reported for only deep endometriosis infiltrating the rectosigmoid and cannot be extrapolated, without caution, to nodules of other locations.

Patients with deeply infiltrating rectosigmoid endometriotic nodules, for which surgical management has not been performed, should undergo surveillance to allow detection of growth of nodules, particularly when continuous amenorrhoea has not been achieved. This recommendation is of importance to young patients with rectosigmoid nodules who wish to conceive, in whom first line ART is planned. There is a very low risk of progression of deep endometriotic nodules infiltrating the rectosigmoid in women with amenorrhoea induced by medical therapy, lactation or pregnancy.

No funding was received for this study. The authors declare no competing interests related to this study.