Transvaginal Ultrasound in the Diagnosis and Assessment of Endometriosis-An Overview: How, Why, and When

Abstract

Endometriosis is a common gynaecological disease, causing symptoms such as pelvic pain and infertility. Accurate diagnosis and assessment are often challenging. Transvaginal ultrasound (TVS), along with magnetic resonance imaging (MRI), are the most common imaging modalities. In this narrative review, we present the evidence behind the role of TVS in the diagnosis and assessment of endometriosis. We recognize three forms of endometriosis: Ovarian endometriomas (OMAs) can be adequately assessed by transvaginal ultrasound. Superficial peritoneal endometriosis (SUP) is challenging to diagnose by either imaging modality. TVS, in the hands of appropriately trained clinicians, appears to be non-inferior to MRI in the diagnosis and assessment of deep infiltrating endometriosis (DIE). The IDEA consensus standardized the terminology and offered a structured approach in the assessment of endometriosis by ultrasound. TVS can be used in the non-invasive staging of endometriosis using the available classification systems (rASRM, #ENZIAN). Given its satisfactory overall diagnostic accuracy, wide availability, and low cost, it should be considered as the first-line imaging modality in the diagnosis and assessment of endometriosis. Modifications to the original ultrasound technique can be employed on a case-by-case basis. Improved training and future advances in ultrasound technology are likely to further increase its diagnostic performance.

Keywords: MRI; deep infiltrating endometriosis; endometriosis; ultrasound.

Figure 1

Typical ovarian endometrioma (OMA) with a ground-glass appearance.

Figure 2

Two small OMAs with typical appearance in the same ovary.

Figure 3

Atypical OMA with papillary projection (green arrow), likely representing a blood clot.

Figure 4

Deep infiltrating endometriosis (DIE) nodule of the bladder appearing as a protrusive nodule arising from the bladder base towards the lumen of the bladder.

Figure 5

Ultrasound image showing the distal part of the ureter (yellow arrows) before it enters the bladder.

Figure 6

In the sagittal plane, the stretched, normal uterosacral ligament (yellow arrow) appears as a thin white line. The presence of a small amount of free fluid (red arrow) facilitates the visualization.

Figure 7

DIE nodule (white arrow) of the uterosacral ligament, appearing as a hypoechoic lesion within the white stripe.

Figure 8

DIE nodule of the uterosacral ligament, visualized as a hypoechoic lesion (white arrow) in the sagittal plane.

Figure 9

DIE nodule of the torus uterinus, appearing as a hypoechoic lesion on the rectrocervical area (yellow arrow). Adjacent to it, a hematosalpinx can be visualized (white arrow).

Figure 10

The normal rectovaginal septum as a thin white line between the posterior vaginal wall and the anterior rectal wall. The black line (which passes just below the inferior limit of the cervix) demarcates the upper limit of the rectovaginal septum.

Figure 11

A small DIE nodule of the rectovaginal septum (yellow arrow), appearing as a hypoechoic lesion with no infiltration of the adjacent vaginal or rectal wall.

Figure 12

Deep endometriosis nodule of the anterior rectal wall, seen as an irregular hypoechoic lesion (white arrow).