OC10.01: Rectal deep endometriosis: transrectal approach with transvaginal probe to assess the infiltration of rectal mucosa

The aim of this study was to evaluate in patients with pelvic deep infiltrating endometriosis (DIE) the accuracy of transrectal ultrasound examination using the transvaginal probe to assess grade of rectal wall infiltration in comparison with colonoscopic, surgical, and histological findings. Fifty-five patients with posterior DIE underwent sonographic evaluation of nodule invasiveness of the rectal wall prior to laparoscopic surgery. To evaluate the extension of the lesion in the rectal wall we use a transvaginal sectorial probe; first transvaginally, than transrectally (TRS). The rectal DIE was classified as: attached only to the rectal serosa, infiltrating the muscularis, or infiltrating the mucosa. Nodule diameters were also measured and correlated to the percentage of rectal stenosis at barium enema or histology. At TVS/TRS examination the DIE lesion infiltrated the rectal mucosa in 5 patients, in 39 patients the lesion infiltrated the muscularis, and in 11 patients the lesion was only adherent to the serosa. Surgery and histology confirmed sonographic findings in all case except in 3 of 11 where the lesion was deeper than sonographically seen, and in 2 of 38 in which the nodule was more superficial and did not invade the muscularis (accuracy 91%). Colonoscopy confirmed all 5 cases rectal mucosa lesions, and revealed only extrinsic compression of the mucosa in 12 of the 38 patients. Rectal stenosis of > 50% was observed in 5 patients who had a mean nodule maximum diameter of 49.2 ± 7.4 mm, this was significantly greater than those who had no or < 50% lumal stenosis (24.9 ± 11.6 mm). Most of the DIE lesions evaluated by TVS/TRS do not infiltrate the rectal mucosa and therefore colonoscopy seems unnecessary in these cases. Nodule dimension correlates to lumal stenosis and therefore barium enema would not be useful in the case of small nodule. TVS/TRS provides accurate information about the infiltration of the rectal wall and can help guide other adjunctive diagnostic testing.