Let's Talk About Ultrasound for Endo and Adeno
By Dannielle Stewart
If you’re a person with pelvic pain, there’s a good chance you’ve been introduced to the transabdominal and/or transvaginal ultrasound. It’s an essential form of imaging in gynaecology, as well as other specialities, and can tell clinicians a great deal what’s happening in the pelvis when diagnosing episodes of pain or bleeding from sources such as ovarian cysts, torsion or fibroids. When it comes to endometriosis and adenomyosis, however, ultrasound can be a contentious subject among clinicians and patients. For many of us, our first dismissal by a clinician came from the humble ultrasound - being told we were fine because a scan showed nothing, only to find out months or years later that endometriosis was covering our insides when visualised at laparoscopy. One of the first things many of us learnt when becoming “endo literate” was that ultrasound cannot rule out endometriosis, and that a scan is not a substitute for the gold standard - a diagnostic laparoscopy by an experienced excision specialist. Imaging technology has come a long way in recent years, particularly transvaginal ultrasound, and in the right hands it can actually prove itself a useful tool in the diagnosis and management of endometriosis and adenomyosis. So what is the role of this scan? What can it see, what can it tell us, and can we in fact diagnose endometriosis on a scan? Let’s talk about ultrasounds.
What is an ultrasound?
Let’s start with the basics. An ultrasound creates an image by sending high frequency sound waves into the area of examination and receiving echoes returning from those tissues. A pelvic ultrasound is performed either transabdominally (TA) (with the transducer on the abdomen) or transvaginally (TVS), with a transducer placed internally in the vagina. The latter method provides a clearer, more comprehensive view of pelvic organs because the transducer is closer to the target tissues. A regular pelvic ultrasound tends to look for abnormalities of the ovaries and fallopian tubes (e.g cysts or ectopic pregnancy), lining of the uterus (e.g. in the case of abnormal or dysfunctional uterine bleeding), and pelvis. This is typically performed by a sonographer and viewed by a radiologist who then writes a report for a referring doctor. This general type of scan is typically the one we’re referring to when we say ultrasound doesn’t typically see endometriosis - it’s your standard scan.
What are some basic things you can see on an ultrasound?
Uterus: size, orientation (anteverted vs retroverted), layers: myometrium, endometrium and junctional zone. Assessing the muscle wall of the uterus (myometrium) is particularly relevant in adenomyosis.
Ovaries: size and volume of the ovary, follicles (these signs may be relevant for PCOS or for diagnosing an acute problem such as ovarian torsion where the ovary may be enlarged), presence of cysts or masses.
Presence of free fluid (e.g. due to cyst rupture or torsion)
Doppler - looks at blood flow and vascularity within the pelvis. This is useful when diagnosing acute conditions such as ovarian torsion, or, in skilled hands, doppler imaging of the uterus may contribute to a diagnosis of adenomyosis
Tertiary Scanners and Endometriosis Scans
A tertiary scanner is a gynaecologist who has undertaken further study to become a subspecialist in obstetrics and gynaecology ultrasound (RANZCOG recognised subspeciality), and is considered an expert in their field in scanning a pelvis. They often perform the scan as well as interpreting it, and in fact consider the imaging a form of clinical examination. It’s not simply something done to rule a condition in or out, it’s a dynamic assessment of the pelvis. Additionally, the scanner is experienced in visualising diseases such as endometriosis and adenomyosis via ultrasound, and is more likely to either make a diagnosis or provide support for a diagnosis that is then confirmed via laparoscopy. This kind of scan also has a role in helping surgeons plan a laparoscopy, particularly where there is the potential for deep infiltrating endometriosis, or an endometrioma.
So can a tertiary scanner see endometriosis on a scan? Yes, but not all endometriosis, and not in every case. Let’s take a quick refresher on the types of endometriosis found within the body
Superficial Endometriosis: lesions within the pelvis less than 5 mm in depth
Deep Infiltrating Endometriosis: lesions that infiltrate the peritoneum by more than 5 mm, also characterized by nodules that infiltrate pelvic structures such as the cul-de-sac, bowel, bladder, uterosacral ligaments and the rectovaginal area (space between rectum and vagina)
Ovarian Endometrioma: an endometrioma is an ovarian cyst that contains thick, tar like fluid, and hence contributes to the name “chocolate cyst”.
Superficial endometriosis is not typically seen on ultrasound, even by a tertiary scanner, and thus not finding endometriosis on an ultrasound does not exclude the diagnosis. However, deep endometriosis and endometriomas can be seen on an ultrasound when examined by a specialist who knows what to look for. An ultrasound can therefore help identify deep endometriosis lesions prior to surgery and help the surgeon establish if other doctors (e.g. colorectal, urology) may be required to safely excise lesions, plan the surgery, and visualise areas that may be a challenge to see during laparoscopy (such as the rectovaginal septum).
Dynamic Scanning and Soft Signs
While one may not always be able to see superficial endometriosis lesions, or even deep endometriosis, on a scan, the current body of clinical literature also suggests that expert, dynamic ultrasound (where the ultrasound is used as part of an overall examination of the pelvis) can identify soft markers of endometriosis that suggest the presence of disease (but still require a laparoscopy to confirm and treat it). While a “hard marker” refers to something like an endometrioma, where the scanner can clearly see and identify the abnormality, soft markers are more subtle and tend to act as a clue that something is there, rather than identifying the thing itself. Some of these markers include reduced ovarian mobility (e.g. from adhesions that fix the ovaries in place, or adhere it to other organs such as the bowel), specific point pelvic tenderness, presence of localised peritoneal fluid in the pelvis, and a negative sliding sign.
A sliding sign is the radiological terminology for assessing whether the rectum and colon glide freely (as they’re supposed to) over the uterine wall. This means that if that normal movement isn’t seen (a negative sliding sign) when using gentle pressure with the ultrasound transducer, there may be quite severe disease present in the pelvis preventing this normal movement from happening. The sliding sign has been found to be highly accurate for predicting, in particular, severe disease and adhesions in the Pouch of Douglas.
Dr Steven Goldstein presented the value of dynamic scanning at the December 2020 ISGE conference, highlighting that soft markers such as those outlined above, could help identify even early/superficial endometriosis using ultrasound in the right hands, and that this is an emerging and exciting field in endometriosis diagnostics. Ultrasound has been identified in the literature as being an important adjunct to surgery in predicting the complexity of the procedure, and guiding the surgical plan. Expert ultrasound can therefore be an important tool for identifying more severe disease, and thus limiting the need for multiple surgeries (if you know you’ll need a complex surgery, you can find the right surgeon for you in the first instance, rather than having a less experienced surgeon do part one, and a specialist do part 2 etc). It can also point your surgeon in the direction of a diagnosis based on soft markers, providing a rationale for surgical treatment.
Current consensus? You can’t rule out endometriosis from a scan alone, laparoscopy remains the gold standard, but expert scanning can be used to predict the complexity of laparoscopic surgery, and triage those awaiting a diagnosis to ensure they receive the best care for their clinical picture!
What About Adenomyosis?
MRI, ultrasound or laparoscopy? How should we go about looking for adenomyosis? All three play a role in the diagnosis, with MRI typically used to support a diagnosis of adenomyosis based on symptoms or visual signs at laparoscopy (you can read more about MRI and adenomyosis diagnosis, as well as those laparoscopy signs here). Like endometriosis, ultrasound cannot definitively rule out adenomyosis, but a tertiary scanner may be able to identify the following four diagnostic criteria to support a diagnosis of adenomyosis:
Loss of clarity of the endometrial/myometrial junction (remember that adenomyosis is a condition where the endometrium grows into the myometrium, or the muscle wall of the uterus, so not being able to clearly see that distinction can be a red flag!)
Glands in the myometrium within the area of suspicion
Increased vascularity in the region of interest as shown on Doppler (remember the Doppler ultrasound looks at blood flow, increased blood flow in that muscle wall of the uterus can point to adeno)
Thickening of the myometrium, one side may be thicker than the other
Though these criteria may point to a diagnosis of adenomyosis, it’s not 100% definitive, some people with adenomyosis may have all, or only some of these, and the scanner’s experience also plays a major part. However, a tertiary scanner can play an important role in illuminating and contributing to the overall clinical picture when considering a diagnosis of adenomyosis.
What’s our takeaway? Ultrasound can play an essential role in supporting a diagnosis of endometriosis and adenomyosis, particularly with regards to laparoscopy planning, however the expertise of the scanner and reviewer plays a major role - so ask your doctor about a tertiary scanner or specialist gynaecology ultrasound centre where scans for endometriosis and adenomyosis are done regularly.
As always, talk through any concerns and questions with your specialist or GP, and check out the QENDO Referral List at qendo.org.au/membership to find an endo friendly professional near you.
References
Fererro, S., Barra, F., Scala, C., & Condous, G. (2021). Ultrasonography for bowel endometriosis. Best Practice & Research Clinical Obstetrics and Gynaecology, 71, 38-50.
Menakaya, U., Reid, S., Lu, C., Bassem, G., Infante, F., & Condous, G. (2016). Performance of ultrasound‐based endometriosis staging system (UBESS) for predicting level of complexity of laparoscopic surgery for endometriosis. Ultrasound in Obstetrics & Gynecology, 48(6), 786-795.
Peterson, N. (2020). Diagnosis. Retrieved from, https://nancysnookendo.com/learning-library/diagnosis/lessons/ultrasound-use-with-endometriosis/
Queensland Xray. (2021). Endometriosis Ultrasound.
Tronc, G. (2018). MRI and the diagnosis of adenomyosis. Retrieved from, https://www.qendo.org.au/blog/mri-and-the-diagnosis-of-adenomyosis?rq=MRI
Zhou, Y., Su., Y., Liu, H., Wu, H., Xu, J., & Dong, F. (2021). Accuracy of transvaginal ultrasound for diagnosis of deep infiltrating endometriosis in the uterosacral ligaments: Systematic review and meta-analysis. Journal of Gynecology, Obstetrics and Human Reproduction, 50.
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