Mild endometriosis of the uterosacral ligaments: a retrospective study of magnetic resonance imaging performance for diagnosis.

ABSTRACT

RESEARCH QUESTION What are the diagnostic performances of magnetic resonance imaging (MRI) scans when used to identify mild endometriosis of the uterosacral ligaments (USL)? DESIGN: Monocentric retrospective study of patients who underwent a pelvic MRI followed by laparoscopy for determination of endometriosis between January 2016 and December 2020. Patients were included whether endometriosis of USL was suspected or not, but patients presenting large lesions that left no doubt as to their endometriotic nature on the MRI were excluded. Six criteria for the description of USL on MRI were studied to determine their diagnostic performances in predicting the presence of endometriosis on laparoscopy as follows asymmetry, thickening, irregularity, straightness, the presence of a nodule or a hypersignal T1 spot. RESULTS: Seventy-seven patients were included. Among the criteria, 'asymmetry' and 'thickening' had the highest sensitivities (0.69 [95% confidence interval 0.54-0.80] and 0.51 [0.40-0.63], respectively) but moderate specificities (0.52 [0.31-0.73] and 0.62 [0.50-0.72]). Conversely, 'irregularity', 'nodule', 'straightness' and 'hypersignal T1 spot' were associated with high specificities (0.81 [0.70-0.89], 0.96 [0.89-0.99], 0.95 [0.87-0.99] and 0.99 [0.93-1.00], respectively) but poor sensitivities (0.22 [0.14-0.33], 0.12 [0.06-0.21], 0.08 [0.03-0.16] and 0.08 [0.03-0.16], respectively). The presence of at least one criterion for the description of the USL was associated with good sensitivity (0.80 [0.66-0.89]) but poor specificity (0.35 [0.16-0.57]). CONCLUSIONS: The results suggest that the identification of minimal changes in the normal appearance of USL should not automatically lead to a conclusion of mild endometriosis at this location.