The accuracy of ultrasound compared to magnetic resonance imaging in the diagnosis of deep infiltrating endometriosis: A narrative review

Endometriosis is defined as the presence of endometrium-like epithelial cells and/or stroma located outside the uterus, generally with associated inflammatory response. Commonly located on the ovaries and peritoneum, endometriosis can also infiltrate the retroperitoneal space and pelvic organs, known as deep endometriosis (DE). This narrative review aims to compare the accuracy of transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI) for detecting deep endometriosis. A literature search was performed mid-2021 and again in December 2022 using PubMed, SAGE and Wiley databases, and limited to studies published between 2011 and 2021. Key words deep infiltrating endometriosis, transvaginal ultrasound, magnetic resonance imaging and diagnostic accuracy identified 16 studies which addressed the aim. The authenticity and reliability were determined by the Standards for Reporting of Diagnostic Accuracy. When the studies were analysed, the diagnosis of DE mean sensitivity values ranged from 40% to 100% for TVUS and 50% to 100% for MRI. Mean specificity values ranged from 81.5% to 99.9% and 84.4% to 97.5%, respectively. This indicates that both MRI and TVUS have similarly accurate performance in the detection of DE. Endometriosis detection is possible with TVUS and MRI, however accuracy is dependent on the location and severity as well as limitations due to operator and image interpretation reliability. In the presence of a correctly performed dynamic TVUS examination for the diagnosis of DE, MRI adds little diagnostic value. Further research is recommended using a standardised protocol in a wider study of affected patients, including accurate clinical assessments for each location of endometriosis to inform the choice of imaging for that region.