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

Endometriosis is a common and painful gynaecological condition that takes an average of 6.4years to diagnose. While laparoscopic surgery is the recommend gold standard in diagnosis of endometriosis, transvaginal ultrasound (TVS) is able to assist surgeons in the planning and management of patients, especially when there is limited visualisation in the posterior compartment. Uterosacral ligaments (USL) are located in the posterior compartment and are one of the first and most common places that endometriosis deposits, The International Deep Endometriosis Analysis (IDEA) group consensus, which are the current guidelines for DE imaging, recommends a thorough ultrasound assessment to identify endometriotic disease. This includes an assessment of anatomic structures in the posterior compartment including the USLs. However, IDEA does not explicitly articulate specifics of USL imaging and measurements on ultrasound. The primary aim of this review is to determine is to identify ultrasound techniques and characteristics of USLs in the diagnosis of deep infiltrative endometriosis (DE). The secondary aim is to describe and summarise these findings into normal and pathological findings. A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A population, interventions, comparator, and outcome framework was used to define a search strategy. Articles were screened using Covidence review management system, and data was extracted by two authors using a standardised and piolet-tested form. Quality assessment was conducted using the Critical Appraisal Skills Programme (CASP). Medline, Embase and Scopus and Google Scholar were searched yielding 250 articles, with 22 being included in the review. Analysis of the data demonstrated inconsistent reporting of ultrasound techniques and characteristics of USLs. Most (20/22) papers described abnormal criteria of USLs, only 5/22 papers determined what the normal USL appearance is or what techniques (11/22) were applied. Even though reporting was heterogeneous, there was a high level of tertiary centre participation with gynaecological experienced operators, therefore was a high level of agreement. Through review of the current literature, this study has investigated ultrasound techniques and characteristics of USLs for the diagnosis of DE. All papers included in this review reported presence of pathological sonographic findings of the USLs when DE was presented therefore it is recommended that USL examination become a part of TVS exams when DE is clinically suspected. This study also demonstrated that there was lack of data and no agreement when it comes to measuring USLs with DE. Even so, the current evidence demonstrates that scanning the USLs, and locating, identifying, and describing USL thickening and endometriotic nodules in the various locations using the described techniques and characteristics in this review has clinical value in early diagnosis.