Uniformity, Standardization in the Sonographic Assessment
In Europe, as in the United States, transvaginal sonography (TVS) is the first-line imaging tool for the diagnosis and management of endometriosis. In Europe, many ob.gyns. perform ultrasound themselves, as do treating surgeons. When diagnostic findings are negative but clinical suspicion is high, MRI is often utilized. Laparoscopy may then be considered in patients with negative imaging results.
Efforts to standardize terms, definitions, measurements, and sonographic features of different types of endometriosis have been made to make it easier for physicians to share data and communicate with each other. A lack of uniformity has contributed to variability in the reported diagnostic accuracy of TVS.
About 10 years ago, in one such effort, we assessed the accuracy of TVS for DIE by comparing TVS results with laparoscopic/histologic findings, and developed an ultrasound mapping system to accurately record the location, size and depth of lesions visualized by TVS. The accuracy of TVS ranged from 76% for the diagnosis of vaginal endometriosis to 97% for the diagnosis of bladder lesions and posterior cul-de-sac obliteration. Accuracy was 93% and 91% for detecting ureteral involvement (right and left); 87% for uterosacral ligament endometriotic lesions; and 87% for parametrial involvement.6
Shortly after, with a focus on DIE, expert sonographers and physician-sonographers from across Europe — as well as some experts from Australia, Japan, Brazil, Chile, and the United States (Y. Osuga from Brigham and Women’s Hospital and Harvard Medical School) — came together to agree on a uniform approach to the sonographic evaluation for suspected endometriosis and a standardization of terminology.
The consensus opinion from the International Deep Endometriosis Analysis (IDEA) group details four steps for examining women with suspected DIE: 1) Evaluation of the uterus and adnexa, 2) evaluation of transvaginal sonographic “soft markers” (ie. site-specific tenderness and ovarian mobility), 3) assessment of the status of the posterior cul-de-sac using real-time ultrasound-based “sliding sign,” and 4) assessment for DIE nodules in the anterior and posterior compartments.7
Our paper describing a mapping system and the IDEA paper describe how to detect deep endometriosis in the pelvis by utilizing an ultrasound view of normal anatomy and pelvic organ structure to provide landmarks for accurately defining the site of DIE lesions (Figure 2).
Dr. Exacoustos
Figure 2: Posterior deep infiltrating endometriosis (DIE)
(A. Ultrasound appearance of a small DIE lesion of the retrocervical area [white arrows], which involved the torus uterinum and the right uterosacral ligament [USL]. The lesion appears as hypoechoic tissue with irregular margins caused by the fibrosis induced by the DIE. B. TVS appearance of small nodules of DIE of the left USL. Note the small retrocervical DIE lesion [white arrows], which appears hypoechoic due to the infiltration of the hyperechoic USL. C) Ultrasound appearance of a DIE nodule of the recto-sigmoid wall. Note the hypoechoic thickening of the muscular layers of the bowel wall attached to the corpus of the uterus and the adenomyosis of the posterior wall. The retrocervical area is free. D. TVS appearance of nodules of DIE of the lower rectal wall. Note the hypoechoic lesion [white arrows] of the rectum is attached to a retrocervical DIE fibrosis of the torus and USL [white dotted line]).
So-called rectovaginal endometriosis can be well assessed, for instance, since the involvement of the rectum, sigmoid colon, vaginal wall, rectovaginal septum, and posterior cul-de-sac uterosacral ligament can be seen by ultrasound as a single structure, making the location, size, and depth of any lesions discernible.
Again, this evaluation of the extent of disease is important for presurgical assessment so the surgeon can organize the right team and time of surgery and so the patient can be counseled on the advantages and possible complications of the treatment.
Notably, an accurate ultrasound description of pelvic endometriosis is helpful for accurate classification of disease. Endometriosis classification systems such as that of the American Association of Gynecologic Laparoscopists (AAGL)8 and the American Society of Reproductive Medicine (ASRM),9 as well as the #Enzian surgical description system,10 have been adapted to cover findings from ultrasound as well as MRI imaging.
A Systematic Evaluation
In keeping with the IDEA consensus opinion and based on our years of experience at the University of Rome, I advise that patients with typical pain symptoms of endometriosis or infertility undergo an accurate sonographic assessment of the pelvis with particular evaluation not only of the uterus and ovaries but of all pelvic retroperitoneal spaces.
The TVS examination should start with a slightly filled bladder, which permits a better evaluation of the bladder walls and the presence of endometriotic nodules. These nodules appear as hyperechoic linear or spherical lesions bulging toward the lumen and involving the serosa, muscularis, or (sub)mucosa of the bladder.
Then, an accurate evaluation of the uterus in 2D and 3D permits the diagnosis of adenomyosis. 3D sonographic evaluation of the myometrium and of the junctional zone are important; alteration and infiltration of the junctional zone and the presence of small adenomyotic cysts in the inner or outer myometrium are direct, specific signs of adenomyosis and should be ruled out in patients with dysmenorrhea, heavy menstrual bleeding, infertility, and pregnancy complications.
Endometriomas of the ovaries can be easily detected as having the typical appearance of a cyst with ground glass content. Adhesions of the ovaries and the uterus also should be evaluated with a dynamic ultrasound approach that utilizes the sliding sign and mobilization by palpation of the organs during the TVS scan.
Finally, the posterior and lateral retroperitoneal compartments should be carefully evaluated, with symptoms guiding the TVS examination whenever possible. Deep endometriotic nodules of the rectum appear as hypoechoic lesions or linear or nodular retroperitoneal thickening with irregular borders, penetrating into the intestinal wall and distorting its normal structure. In young patients, it seems very important to assess for small lesions below the peritoneum between the vagina and rectum, and in the parametria and around the ureter and nerves — lesions that, notably, would not be seen by diagnostic laparoscopy.