OP31.11: Follow‐up of MRI deep infiltrative endometriotic lesions before and after pregnancy: does it change something?

To compare with MRI, the size of the lesions of deep infiltrative endometriosis (DIE), endometriomas (OMA) and adenomyosis, and before and after pregnancy. Retrospective study in departments of obstetrics and gynecology of the Cochin-Port-Royal Hospital Paris V Rene Descartes, Paris, France. Between October 2015 and December 2016, 21 pregnant women affected with endometriosis diagnosed at MRI before pregnancy and who were offered pelvic MRI after pregnancy, were included. Two sets of 21 MRI (1,5T) examinations performed with an identical protocol, before and after pregnancy, were reviewed independently 1 month apart by the same experienced radiologist to avoid memory contamination and inter-operator variability. Volume of DIE lesions (uterosacral ligaments, vaginal posterior fornix, and bowel and bladder involvement) and endometriomas were assessed. Adenomyosis were evaluated by measuring the ratio between thickness of myometrium and junctional zone. Pre and post partum MRI were performed by the same radiologist who is considered as a referent practitioner for the diagnosis of endometriosis. The mean time interval between prepartum MRI and delivery was 561 ± 267 days and the mean time interval between delivery and post partum MRI was 272 ± 164 days. A statistically significant change of the overall initial volume was observed with a reduction of 46% for DIE lesions (238 ± 3258 mm3 vs. 1310 ± 3160 mm3, p < 0.01) and 34% for endometriomas size (10.3 ± 11.3 vs 6.8 ± 11.8, p = 0.03). A reduction of 22% for bowel lesions was observed (4245 ± 4579 mm3 vs. 3342 ± 5552, p = 0.06). No differences were observed for junctional zone, myometrium thickness and ZJ/M ratio. No increase of lesions volume was observed. Our data support that the size of DIE and OMA lesions decrease significantly after pregnancy.