Proposed technique to visualize and classify uterosacral ligament deep endometriosis with and without infiltration into parametrium or torus uterinus

Abstract

The uterosacral ligaments (USL) have been reported to be the most common site of deep endometriosis (DE) in the pelvis 1 . A nodule within the USL may infiltrate the parametrium, increasing the complexity of surgical resection, and larger nodules (≥ 17 mm) noted on transvaginal ultrasound (TVS) should raise suspicion of ureteral involvement 2 . Nodules may also invade the torus uterinus, which is the thickening between the insertion of the USL behind the posterior cervix. The diagnostic test accuracy of TVS for USL DE is only moderate, with sensitivity and specificity of 67% and 86%, respectively 3 , which may be related to the absence of a standardized technique for its assessment. We present a method that allows easier identification of normal and abnormal USL and classification of USL DE nodules.The proposed method for TVS assessment of USL is summarized in Videoclip S1 and consists of the following steps.1. Insert the TVS probe into the posterior vaginal fornix behind the cervix and uterus. 2. Decrease the penetration depth of field and position the focal point nearest to the probe. 3. Angle the probe toward the rectum in the midsagittal position ( Figure S1). Visualize the hypoechoic posterior vaginal fornix nearest to the probe; adjacent is the hyperechoic pouch of Douglas peritoneum. Follow this hyperechoic line closely in the next step. 4. To evaluate the right USL, simultaneously sweep the ultrasound beam to the patient's right ( Figure S1) and rotate clockwise (usually not more than 45 • ); the hyperechoic line (peritoneum) should begin to thicken. The USL should be evaluated at the thickest point of the hyperechoic line. For the left USL, follow the same procedure, but instead rotating the probe counterclockwise. 5. If a hypoechoic lesion is seen within the hyperechoic USL ( Figures S2 and S3), measure it in three orthogonal planes ( Figure S4). 6. Evaluate the portion of the nodule that is within the borders of the USL and characterize the lesion according to the proposed USL DE classification system (Table 1, Figures 1 and 2), in line with the leiomyoma subclassification of submucosal leiomyomas 4 . 7. Evaluation of the ureters should always be performed ( Figure S5). A ureter of ≥ 6 mm in diameter should be considered as dilated. The kidneys should be assessed for hydronephrosis 5 .We believe that the proposed USL DE classification system (Table 1) provides a simple and standardized approach to describe such lesions, which may assist sonographers and surgeons in predicting ureteral involvement and/or the need for ureterolysis. Corresponding surgical images of USL DE with parametrial involvement are shown in Figure S6. Of course, evaluation of the USL DE classification system for its utility in diagnosis and/or preoperative planning is required before clinical implementation is considered.

Diagnostic Accuracy of Ultrasound and MRI in the Mapping of Deep Pelvic Endometriosis Using the International Deep Endometriosis Analysis (IDEA) Consensus

“…Another factor to consider is generally difficult visualisation of USLs on the ultrasound, owing to their noncontrasting echogenicity and lack of standardised ultrasound technique. e latter was addressed in a recent communication by Leonardi et al [21], suggesting a systematic structured approach to visualising USLs.…”

A pictorial guide to the ultrasound identification and assessment of uterosacral ligaments in women with potential endometriosis

“…When a USL DE nodule is noted in our clinical practice, we evaluate whether the nodule is contained within the USL or extends into the parametrium and/or torus uterinus (defined as the thickening between the insertion of the USLs behind the posterior cervix; this area may also be known as the retrocervix). If there is infiltration into either of these structures, we document the proportion of the lesion that is within the USL versus the parametrium/torus uterinus, as per the recently published proposed USL DE classification system (Table ), which was inspired by the classification system of submucosal leiomyomas . This system has not yet been validated and does not have demonstrated reproducibility beyond our unit, so we suggest use with caution for now.…”

“…DE , Deep Endometriosis; USL , Uterosacral Ligament. Reprinted with Permission from Wiley Publishers …”

Differential Diagnosis of Endometriosis by Ultrasound: A Rising Challenge

“…Retroperitoneal endometriosis near the uterus (i.e., paracervical and parametrial) is common [ 17 , 41 ], and ultrasound is a valid tool to identify these lesions [ 11 , 42 , 43 , 44 , 45 ]. A DD that includes the spread of cervical cancer warrants attention [ 46 ].…”