International survey finds majority of gynecologists are not aware of and do not utilize ultrasound techniques to diagnose and map endometriosis

Transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) have been demonstrated to have a high diagnostic accuracy for ovarian endometriomas (OE), deep endometriosis (DE) and pouch of Douglas (POD) obliteration when performed and reported by experts1. With the exception of recognizing superficial endometriosis, non-invasive imaging can play an important role in surgical planning2, 3. In the case of bowel DE and POD obliteration, imaging can negate the need for a two-step surgical process (diagnostic followed by therapeutic) and is also cost-saving4. Overall, ultrasound technology is more accessible and less expensive than MRI and is considered the first-line imaging modality for gynecological health concerns, and, thus, is the focus of this article. The International Deep Endometriosis Analysis (IDEA) group formulated a consensus opinion on the terms, definitions and measurement methods that may be used to describe the ultrasound features of the different phenotypes of endometriosis5. For the purpose of this article, we consider and have defined TVS as recommended by the IDEA group as advanced TVS. Briefly, this involves assessment of the uterus for adenomyosis, the ovaries for endometriomas and immobility, deep endometriosis throughout the pelvis (bladder, ureters, bowel, uterosacral ligaments, vagina, rectovaginal septum (RVS)) and the POD for obliteration. In contrast, a basic TVS examination is limited in scope and follows the current recommendations of many ultrasound organizations internationally. For example, in North America, the American Institute of Ultrasound in Medicine (AIUM), the Canadian Association of Radiologists (CAR) and the Society of Obstetricians and Gynaecologists of Canada (SOGC) recommend that a female pelvic ultrasound examination (i.e. basic TVS) consist of assessment of the uterus, ovaries and POD (for ‘free fluid or a mass’ only)6, 7. The Society & College of Radiographers (SCoR) and the British Medical Ultrasound Society (BMUS) in the UK recommend the same, but to additionally assess the bladder and vagina8. The assessment of DE is almost entirely absent in these recommendations. Much of the evidence to support the IDEA consensus opinion and the advancement of ultrasound has originated from highly specialized gynecological ultrasound units, not necessarily representing the norm in clinical practice worldwide. In order to work toward the goal of global non-invasive ultrasound investigation of endometriosis as per the IDEA group, we surveyed obstetrician-gynecologists (OBGYNs) on how they think of and use advanced TVS in the diagnosis and management of endometriosis (Appendices S1 and S2). Beginning to understand the awareness of OBGYNs outside of highly specialized gynecological ultrasound units is the first step in advocating for and implementing advancement in the diagnostic and therapeutic care elements that patients with endometriosis deserve. The target potential respondents of the survey were OBGYNs holding membership with the general obstetrics/gynecology societies of Australia and New Zealand (Royal Australian New Zealand College of Obstetricians and Gynaecologists (RANZCOG)), Canada (SOGC) and the USA (American College of Obstetricians and Gynecologists (ACOG)) and the UK's endoscopy society (British Society of Gynaecological Endoscopy (BSGE)). This survey provided an appreciation of the current poor awareness and underutilization of advanced TVS by OBGYNs (n = 1140 respondents: Australia and New Zealand n = 449; Canada n = 156; UK n = 95; USA n = 440) in the evaluation of patients with suspected or confirmed endometriosis. There was an appropriate distribution of OBGYNs across age, practice location (community vs academic), fellowship training and surgical skill set (Tables S1 and S2). Fewer than 50% of respondents in all regions described using advanced TVS for most or all of their patients, and there were large differences noted between regions (Table 1). Some respondents stated that advanced TVS is unavailable in their area, with the highest (14%) report of unavailability being in Canada. Significant variations in the use of diagnostic laparoscopy and MRI were also noted. For respondents in Australia and New Zealand and the UK, it does not appear that the greater rate of use of advanced TVS (relative to other regions) necessarily limits the use of diagnostic laparoscopy, which we would expect as those with OE, DE or POD obliteration on TVS would not require diagnostic laparoscopy. Despite the present state of use of advanced TVS, it seems that OBGYNs may be learning of its promise. For all sites of DE, adhesions (POD obliteration and ovarian fixation) and adenomyosis, respondents had higher rates of belief in the potential of advanced TVS compared to what they expect from a TVS examination in their center (Figure 1). Unfortunately, the belief that advanced TVS can detect the two most common sites of DE (bowel and uterosacral ligament) is still lower than 50% in Canada, UK and USA and just above 50% in Australia and New Zealand, which indicates that current research has not yet reached most OBGYNs. Of course, the rates of utilization and expectation/belief of the potential of advanced TVS may be artificially inflated due to bias from respondents, who may have been drawn to survey completion because they are more engaged with endometriosis care and/or imaging. Therefore, awareness and utilization of advanced TVS may be lower than thought based on the survey results. Finally, respondents varied in their answer on what they believed is the most important piece of information about a patient's potential endometriosis before making surgical treatment suggestions. This demonstrates inconsistency in aspects such as training and regional nomenclature. In both Australia and New Zealand and Canada, respondents stated that bowel DE is the most important, compared to the UK and USA respondents, who stated RVS DE and endometriomas are the most important, respectively (Figure S1). We believe that the limited knowledge and integration and variations in adoption of advanced TVS is multifactorial, including factors such as suboptimal practice guidelines and educational differences in core and fellowship training programs. In Australia and New Zealand, a proportion of OBGYNs complete the RANZCOG-accredited Certification in Obstetrical and Gynaecological Ultrasound (COGU) fellowship, becoming experts in this specific area. The acquisition of ultrasound expertise in addition to clinical expertise in obstetrics/gynecology likely contributes to the more advanced nature of gynecological TVS in Australia and New Zealand. In North America, general radiology manages the bulk of obstetric/gynecological ultrasound, which exists in a sea of other imaging modalities and imaging of all other pathologies. Sonographers are generally the ones performing ultrasound and, as yet, there has been little or no attempt to introduce advanced TVS concepts for endometriosis into their education9. Though the rate of MRI utilization in the USA was low, there is a disproportionate amount of literature on MRI, compared to advanced TVS, for endometriosis being produced in the USA10-12. The rate of utilization of MRI in the UK (Table 1) may permit the BSGE respondents to manage their patients appropriately, but it may also be limiting the necessity to increase accessibility and adoption of advanced TVS, which is equally useful and cheaper and easier to facilitate. Nonetheless, the 2017 National Institute for Health and Care Excellence (NICE) guideline and the 2010 ACOG Practice Bulletin state that DE ‘involving the bowel, bladder or ureter’13 or ‘the rectum or RVS’14, respectively, can be assessed using ultrasound. Conversely, the most recent SOGC guideline states that rectal ultrasonography can be used, but there is no mention of advanced techniques using pelvic TVS15. The significant difference between what respondents expect from the TVS examinations in their regions and what they believe can potentially be identified may stem from delayed adoption of novel techniques, limitations in practice guidelines and/or cynicism if clinicians have yet to witness the true potential of advanced TVS for themselves. Beyond clinical practice, practice guidelines indirectly drive national educational standards for residency training programs. Not surprisingly, gynecological ultrasound education differs between the regions studied16. In particular, Canada is lagging behind the other regions in its required graduating standards for gynecological ultrasound17, which may contribute to the lowest rate of utilization of advanced TVS. Improvements in gynecological ultrasound training in residency programs is recommended. In curriculum planning, there are now a number of learning-curve studies for detecting DE using TVS to use as guidance18-20. The other glaring difference between regions is which endometriosis feature respondents considered to be the most important of which to be aware preoperatively (Figure S1). Based on our own clinical practice, we agree with the respondents from Australia and New Zealand and Canada that DE of the bowel is probably the most important in this regard. The main reason for this is that the vast majority of gynecologists do not have the training to manage bowel disease21. As the goal in endometriosis surgery is generally to achieve complete excision and avoid abandonment/complication in the first surgery, preparation by requesting the preoperative work-up and presence of a colorectal surgeon intraoperatively when bowel DE is present is key22. We question whether the UK respondents were potentially grouping together all disease of the posterior compartment or ‘rectovaginal area’, hence their selection of RVS DE as the most important feature23. It has been, and remains to be, unfortunately common to use the term ‘rectovaginal endometriosis’24-27. Isolated endometriosis of the RVS is very rare5 and so to state this is the most important site of DE of which to be aware preoperatively is difficult to justify. We highlight this point because standardized nomenclature amongst surgeons and between sonologists/radiologists and surgeons is paramount. The IDEA consensus opinion was born out of this heterogeneity noted in the literature on the diagnostic accuracy of advanced TVS for endometriosis5. We believe that using terms such as uterosacral ligament, torus uterinus, posterior vaginal fornix, rectum/rectosigmoid junction/sigmoid colon and RVS, rather than the generic term ‘rectovaginal endometriosis’, optimizes our understanding of the disease (including possible etiology, progression and symptomatology) and a surgeon's ability to excise disease with negative margins. Endometriomas were identified as the most important feature amongst respondents in the USA, and ranked in the top three for all regions. We believe this is a practical response in light of to what most gynecological surgeons have access in terms of imaging capabilities (i.e. broad accessibility to basic TVS). Some of the above-noted differences in guidelines and surgical and ultrasound educational standards may also provide an explanation. Across all regions, it may be that respondents do not readily acknowledge more serious forms of disease such as bowel DE and/or POD obliteration preoperatively because these states necessitate skill beyond that of most gynecologists. In those without fellowship-level training, preoperative knowledge of advanced stages of endometriosis surgery may demand relinquishment of their patients' management, resulting in lost income. We are of the opinion that it is time that the majority of endometriosis surgical care is grouped in centers of expertise, though advanced TVS needs to be widely accessible to assist in triaging and resource allocation28. There are variations in availability and utilization of advanced TVS for endometriosis, nomenclature, education and culture of OBGYNs across various regions of the world. While a large collective of international sonology experts has published the IDEA group consensus opinion on ultrasound for endometriosis5, classification of endometriosis surgically has been controversial29 since the concept of standardized classification originated. We advocate for the unification of those in the worlds of imaging and surgery, which could be possible with collaboration and standardization by organizations such as the International Society of Ultrasound in Obstetrics and Gynecology and the International Society for Gynecologic Endoscopy, in addition to national governing bodies in both obstetrics/gynecology and radiology. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.