Ultrasound Characteristics and Scanning Techniques of Uterosacral Ligaments for the Diagnosis of Endometriosis: A Systematic Review

Ultrasound of the uterosacral ligaments: A reliability study for diagnosing endometriosis in Australian non-specialised medical imaging and radiology settings

Introduction/Background

Uterosacral ligaments (USL) are the most common sites of endometriosis. Transvaginal ultrasound (TVS) demonstrates high diagnostic accuracy for endometriosis of the USLs using standardised technique and characterisations. While high accuracy and reproducibility is established with these techniques by well-trained professionals, the question still remains if these techniques are reproducible in general settings. This study aims to assess the intra and interobserver agreement of TVS characteristics of USLs, between experienced and less experienced examiners in an Australian general ultrasound imaging practice, where sonographers are required to perform ultrasound for endometriosis.

Methods

Forty-two patients, with and without known endometriosis, underwent ultrasound imaging of the USLs. Images were obtained of uterosacral ligaments and collated for interobserver survey. Six professional observers independently reviewed the images, classifying characteristics such as echogenicity, echotexture, contour, thickness, and presence of nodules. Interobserver reliability was assessed using Gwet's agreement coefficients (AC1), and the correlation between USL thickness and endometriosis was analyzed using Spearman's correlation.

Results

Interobserver agreement for detecting USL endometriosis was substantial (AC1 = 0.63), with an overall agreement of (0.65) for the seven USL characteristics. Intraobserver agreement ranged from moderate (0.60) to almost perfect (0.96). Experience did not significantly affect intraobserver reliability. A strong positive correlation was found between USL thickness and endometriosis (r = 0.7965, P < 0.01).

Conclusion

This study demonstrates high inter and intraobserver agreement among sonographers and radiologists in a general imaging department for identifying USL characteristics and diagnosing USL endometriosis. Both experienced and less experienced operators can reliably assess USLs Consistency was shown in identifying thickened uterosacral ligaments however, there is no consensus on where uterosacral ligament be measured. Even so, a thickened USL can prompt further extension of the pelvic scan to look for other endometriosis markers.

Clues to revising the conventional diagnostic algorithm for endometriosis

Endometriosis is a complex gynecologic disorder characterized primarily by symptoms of pelvic pain, infertility, and altered quality of life. National and international guidelines highlight the diagnostic difficulties and lack of conclusive diagnostic tools for endometriosis. Furthermore, guidelines are becoming questionable at an increasingly rapid rate as new diagnostic techniques emerge. This work aims to provide a knowledge synthesis of the relevance of various diagnostic tools and to assess areas of improvement of conventional algorithms. MEDLINE and Cochrane Library databases were searched from January 2021 to December 2023 using relevant key words. Articles evaluating the diagnostic relevance and performance of various tools were included and independently reviewed by the authors for eligibility. Included studies were assessed using the GRADE and QUADAS-2 tools. Of the 4204 retrieved articles, 26 were included. While anamnesis and clinical examination do contribute to diagnostic accuracy, their level of evidence and impact on the diagnostic process remains limited. Although imaging techniques are recommended to investigate endometriosis, ultrasonography remains highly operator dependent. Magnetic resonance imaging appears to exhibit higher sensitivities than ultrasound. However, concerns persist with regards to the terminology, anatomical definition of lesions, and accuracies of both ultrasound and magnetic resonance imaging. Recently, several biological markers have been studied and cumulative evidence supports the contribution of noncoding RNAs to the diagnosis of endometriosis. Marginal improvements have been suggested for anamnesis, clinical examination, and imaging examinations. Conversely, some biomarkers, including the saliva microRNA signature for endometriosis, have emerged as diagnostic tools which inspire reflection on the revision of conventional diagnostic algorithms.

Douglas Pouch Fluid Improves the Accuracy of Transvaginal Ultrasound in the Diagnosis of Uterosacral Ligaments Deep Infiltration Endometriosis: A Prospective Study

OBJECTIVES

To compare the accuracy of transvaginal ultrasound (TVUS) with laparoscopy in detecting and characterizing uterosacral ligament (USL) nodules of deep infiltrative endometriosis (DIE) between patients with and without pouch of Douglas (POD) fluid.

METHODS

This prospective study was conducted between June 2021 and July 2023. We included patients from the Second People's Hospital of Shenzhen with two TVUS tests: no POD fluid on the first TVUS test and POD fluid on the second TVUS test. POD fluid was obtained in two ways: naturally occurring fluid during the luteal phase of the menstrual cycle and SonoPODography. Laparoscopic results are the gold standard. To compare the diagnostic performance of TVUS in the diagnosis of DIE on USLs with and without POD fluid.

RESULTS

We included 42 patients with a mean age of 36.4 ± 5.4 years. The maximum length diameter for DIE nodules on USLs with and without POD fluid was 13.3 ± 3.3 mm and 10.2 ± 2.5 mm (P < .001), respectively, while the depth of infiltration was 8.1 ± 2.4 mm and 6.1 ± 1.4 mm (P < .001), respectively. When compared to laparoscopic findings, TVUS findings with and without POD fluid resulted in a sensitivity, specificity, accuracy, positive predictive value, negative predictive value area under the curve, and Cohen kappa of 92.3%, 93.8%, 92.9%, 96.0%, 88.2%, 0.930, and 0.850 and 61.5%, 93.8%, 73.8%, 94.1%, 50.0%, 0.766, and 0.499, respectively. Laparoscopy showed USL involvement in up to 59.5% of patients. With or without fluid, the most common ultrasound features of DIE lesions were USL thickening, irregular morphology, clear boundaries, low echo, and no blood flow signal.

CONCLUSIONS

For patients with clinical suspicion of DIE, TVUS with POD fluid has a higher accuracy for diagnosing USL DIE than TVUS without POD fluid.

Relationship Between Ultrasound Diagnosis, Symptoms and Pain Scale Score on Examination in Patients with Uterosacral Ligament Endometriosis

Background/Objectives: This study investigated patient pain descriptors for transvaginal ultrasound (TVS) diagnostic evaluation of endometriosis for uterosacral ligaments (USLs), including correlation between USL thickness and site-specific tenderness (SST). It further investigated if SST could positively assist diagnosing endometriosis on TVS. Methods: TVS images and SST pain descriptors were collected from 42 patients. SST was evaluated by applying sonopalpation during TVS. The images were presented to six observers for diagnosis based on established USL criteria. Following this, they were given the SST pain scores and asked to reevaluate their diagnosis to assess if the pain scores impacted their decision. Results: An independent t-test showed that the patients with an endometriosis history had higher pain scores overall (7.2 ± 0.59) compared to the patients with no history (0.34 ± 0.12), t (40) = 8.8673. Spearman's correlation showed a strong correlation to the pain scale score for clinical symptoms (r = 0.74), endometriosis diagnosis (r = 0.78), USL thickness (r = 0.74), and when USL nodules were identified (r = 0.70). Paired t-tests showed that the observers demonstrated a higher ability to correctly identify endometriosis with the pain scale information (33 ± 8.83) as opposed to not having this information (29.67 ± 6.31), which was a statistically significant change of 3.33, t (5) = 2.7735. Conclusions: Patients with an endometriosis history have significantly higher pain scores on TVS compared to patients with no endometriosis history. A strong correlation was shown between SST pain scores and patient symptoms, USL thickness, and USL nodules. Inclusion of SST alongside TVS imaging shows promise, with these results demonstrating a higher ability to diagnose endometriosis with additional SST pain scale information.

Society of Radiologists in Ultrasound Consensus on Routine Pelvic US for Endometriosis

Endometriosis is a prevalent and potentially debilitating condition that mostly affects individuals of reproductive age, and often has a substantial diagnostic delay. US is usually the first-line imaging modality used when patients report chronic pelvic pain or have issues of infertility, both common symptoms of endometriosis. Other than the visualization of an endometrioma, sonologists frequently do not appreciate endometriosis on routine transvaginal US images. Given a substantial body of literature describing techniques to depict endometriosis at US, the Society of Radiologists in Ultrasound convened a multidisciplinary panel of experts to make recommendations aimed at improving the screening process for endometriosis. The panel was composed of experts in the imaging and management of endometriosis, including radiologists, sonographers, gynecologists, reproductive endocrinologists, and minimally invasive gynecologic surgeons. A comprehensive literature review combined with a modified Delphi technique achieved a consensus. This statement defines the targeted screening population, describes techniques for augmenting pelvic US, establishes direct and indirect observations for endometriosis at US, creates an observational grading and reporting system, and makes recommendations for additional imaging and patient management. The panel recommends transvaginal US of the posterior compartment, observation of the relative positioning of the uterus and ovaries, and the uterine sliding sign maneuver to improve the detection of endometriosis. These additional techniques can be performed in 5 minutes or less and could ultimately decrease the delay of an endometriosis diagnosis in at-risk patients.

Prospective diagnostic test accuracy of transvaginal ultrasound posterior approach for uterosacral ligament and torus uterinus deep endometriosis

OBJECTIVE

To determine the diagnostic test accuracy of transvaginal ultrasound (TVS) using a standardized technique for the diagnosis of deep endometriosis (DE) of the uterosacral ligaments (USLs) and adjacent torus uterinus (TU).

METHODS

This was a prospective diagnostic test accuracy study conducted at the McMaster University Medical Center Tertiary Endometriosis Clinic, Hamilton, ON, Canada. Consecutive participants were enrolled if they successfully underwent TVS and surgery by our team from 10 August 2020 to 31 October 2021. The index test was TVS using a standardized posterior approach performed and interpreted by an expert sonologist. The reference standard included direct surgical visualization on laparoscopy by the same person who performed and interpreted the ultrasound scans. Accuracy, sensitivity, specificity, positive and negative predictive values (PPV and NPV) and positive and negative likelihood ratios were calculated for the TVS posterior approach for each location using the reference standard.

RESULTS

There were 54 consecutive participants included upon completion of laparoscopy and histological assessment. The prevalence of DE for the left USL, right USL and TU was 42.6%, 22.2% and 14.8%, respectively. Based on surgical visualization as the reference standard, TVS demonstrated an accuracy of 92.6% (95% CI, 82.1-97.9%), sensitivity of 82.6% (95% CI, 61.2-95.1%), specificity of 100% (95% CI, 88.8-100%), PPV of 100% and NPV of 88.6% (95% CI, 76.1-95.0%) for diagnosing DE in the left USL. For DE of the right USL, TVS demonstrated an accuracy of 94.4% (95% CI, 84.6-98.8%), sensitivity of 75.0% (95% CI, 42.8-94.5%), specificity of 100% (95% CI, 91.6-100%), PPV of 100% and NPV of 93.3% (95% CI, 84.0-97.4%). For DE of the TU, TVS demonstrated an accuracy of 100% (95% CI, 93.4-100%), sensitivity of 100% (95% CI, 63.1-100%), specificity of 100% (95% CI, 92.3-100%), PPV of 100% and NPV of 100%.

CONCLUSIONS

We observed high diagnostic test accuracy of the evaluated standardized TVS technique for assessing DE of the USLs and TU. Further studies evaluating this technique should be performed, particularly with less experienced observers, before considering this technique as the standard approach. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.