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Diagnostic Options

Diagnostic options for endometriosis are traditionally a significant challenge that typically causes delays of about 4-11 years from the onset of symptoms. However, some exciting new potential options are emerging that could transform the difficult journey many women take. The current estimates are that endometriosis affects:

  • Around 10-15% of women
  • 35-50% of the women who don’t get pregnant within two years of trying (infertile)
  • The condition reduces monthly conception rates by 50% 

The journey to an endometriosis diagnosis is long and fraught for many women, and the main challenge is that the gold standard for diagnosis is an invasive surgical procedure. While the symptoms of endometriosis are personal and varied, experienced researchers have suggested a remedy to the delays in diagnosis by providing: i

  • Better patient education
  • Quicker referral to healthcare providers
  • A different approach by physicians

Their suggestion is that the diagnosis should focus on the chronic, systemic and inflammatory nature of the disease that involves pelvic pain and infertility, rather than the current focus that relies almost exclusively on the results of surgery and lesion biopsies. 

Diagnostic options for endometriosis are further complicated by there being three distinct types of endometriosis:

  1. Superficial peritoneal lesions
  2. Cysts that create “endometriomas”, which are often in or on ovaries 
  3. Deep infiltrating endometriosis (DIE)


The lesions that form endometriosis can grow in a variety of locations, and the additional challenges that complicate a possible diagnosis include:

  1. The different types of endometriosis have distinct symptoms and appearance
  2. The location of the endometriosis affects the ease of diagnosis
  3. The severity and extent of endometriosis lesions have little bearing on the pain and other symptoms connected to the condition
  4. The endometriosis that’s typically seen in adolescent girls often differs from adults, and this naturally affects diagnosis rates


Some techniques can diagnose some types of endometriosis accurately but can’t detect other types at all. Several avenues are currently being explored to find non-invasive and accurate tests that can be easily accessible.  iii

Diagnostic methods

  1. Surgery
  2. Imaging
  3. Blood tests
  4. The microbiome
  5. Symptoms 

1. Surgery 

Surgery is the only definitive option currently available to diagnose endometriosis, and laparoscopic “keyhole” surgery is the “gold standard” option. The visual diagnosis is usually confirmed by analysis of tissue removed from the pelvis, but relying on laparoscopy is a problem because it’s:

  • Expensive
  • Invasive
  • Traumatic and can cause disease
  • Not universally available
  • Considered a “last resort” option for many
  • Heavily reliant on the skill and experience of the operator

The fundamental issues of access, costs, accuracy, and side effects mean surgery is usually only considered when the woman has clear signs of endometriosis, or the couple has unexplained infertility.

2. Imaging

Two different non-invasive modalities are routinely used to make a presumptive diagnosis of endometriosis:

  1. Transvaginal ultrasound (TVUS) 
  2. Magnetic resonance imaging (MRI) 

These are both accurate options for endometriosis when it forms recognisable structures in high-risk areas. Although they’re not 100% accurate and don’t have the confirmation of a biopsy, they’re excellent for two of the forms. 

However, endometriosis lesions vary in appearance, and they can distort anatomy, which complicates the interpretation of images. Being able to distinguish endometriosis from other potential diseases is crucial when medics need to decide on treatment options.

Transvaginal ultrasound is a relatively low expense, low invasion and easy access option. It’s almost as accurate as MRI for endometriomas and deep infiltrating endometriosis, but it’s highly operator-dependent, and user experience and quality of equipment are major factors affecting TVUS accuracy.  iv

While transvaginal ultrasound is around 93% accurate in diagnosing endometriomas, neither it nor MRI can detect superficial endometriosis. v

Magnetic Resonance Imaging (MRI) is the best imaging technique for mapping deep infiltrating endometriosis (DIE) as it provides a more reliable map of the disease than physical examination or TVUS. While it’s less operator-dependent than TVUS, it’s less accessible, more invasive and more expensive. MRI use is usually reserved for complex cases that need greater clarity than TVUS can provide, and in preoperative planning. vi

3. Blood tests

Blood serum hormone levels are not diagnostic for endometriosis, but AMH and FSH levels are significantly altered in women with endometriosis. If these sex hormone levels are normal, it means endometriosis is much less likely.

Testosterone level  Low
Luteinizing hormone (LH) level Low
Follicle-stimulating hormone (FSH) level High
Anti-Mullerian hormone (AMH) level  Low
GnRH secretions from the hypothalamus Low 


MicroRNAs are a class of small RNA molecules that play a major role in regulating protein expression in normal and diseased cells. A potential breakthrough in diagnosis involves analysing combinations of blood serum microRNAs involved in endometriosis. Recent research has shown they can be very accurate diagnostic biomarkers of endometriosis. vii

This testing technology is currently in its infancy as far as “point of care” is concerned. The particles are tiny, and the differences in miRNA sequences can be fractional, which makes precision design essential. While many techniques and strategies for miRNA detection have been developed, their use was still experimental in 2019. ix

4. The Microbiome

There’s a close connection between the flora in the gut, the peritoneal fluid and endometriosis, and analysis of the microbiome of patients with endometriosis have shown they have significantly:

  • Lower levels of Lachnospiraceae Ruminococcus in the gut
  • Higher levels of Pseudomonadaceae Pseudomonas in the peritoneal cavity

These findings could potentially provide opportunities for non-invasive diagnosis and therapies in the future. x The research is a reminder of the close connection between general health, diet and endometriosis. It reinforces our recommendation that anyone who suspects they have endometriosis follow the advice for their PFP alongside diet and supplement advice for the condition.

5. Symptoms

Diagnosing endometriosis by symptomology is not possible because the strength of symptoms doesn’t connect well to the severity of the condition. However, symptoms are a core issue, especially with deep infiltrating endometriosis and generally involve abnormal pain: 

  • Period pains that can be disabling and can extend into the lower back and legs
  • Pelvic pain throughout the month
  • Pain during and after sex
  • Pain at ovulation
  • Abdominal pain when exercising or moving
  • Urinary pain, urgency and frequency
  • Pain with opening the bowels

Two unfortunate aspects of endometriosis increase the pain experience:

  • Endometriosis lesions have a rich nerve supply to transport the pain experience
  • The condition is driven by high estrogen and low testosterone levels, which significantly increase a person’s sensitivity to pain

Photo by Hush Naidoo Jade Photography on Unsplash

i Sanjay K. Agarwal, et al., Clinical diagnosis of endometriosis: a call to action, American Journal of Obstetrics and Gynecology, Volume 220, Issue 4, 2019, Pages 354.e1-354.e12, ISSN 0002-9378, https://doi.org/10.1016/j.ajog.2018.12.039.
ii By BruceBlaus. Medical gallery of Blausen Medical 2014 WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436
iii L. Kiesel & M. Sourouni (2019) Diagnosis of endometriosis in the 21st century, Climacteric, 22:3, 296-302, DOI: 10.1080/13697137.2019.1578743
iv Noventa, M.; et al. Imaging Modalities for Diagnosis of Deep Pelvic Endometriosis: Comparison between Trans-Vaginal Sonography, Rectal Endoscopy Sonography and Magnetic Resonance Imaging. A Head-to-Head Meta-Analysis. Diagnostics 2019, 9, 225. https://doi.org/10.3390/diagnostics9040225
v L. Kiesel & M. Sourouni (2019) Diagnosis of endometriosis in the 21st century, Climacteric, 22:3, 296-302, DOI: 10.1080/13697137.2019.1578743
vi Celli V, Ciulla S, Dolciami M, et al. Magnetic Resonance Imaging in endometriosis-associated pain. Minerva Obstetrics and Gynecology. 2021 Oct;73(5):553-571. DOI: 10.23736/s2724-606x.21.04782-1. PMID: 33904689.
vii Romanski, P.A., Brady, P.C., Farland, L.V. et al. The effect of endometriosis on the antimüllerian hormone level in the infertile population. J Assist Reprod Genet 36, 1179–1184 (2019). https://doi.org/10.1007/s10815-019-01450-9
viii Sarah Moustafa, et al., Accurate diagnosis of endometriosis using serum microRNAs, American Journal of Obstetrics and Gynecology, Volume 223, Issue 4, 2020, Pages 557.e1-557.e11, ISSN 0002-9378, https://doi.org/10.1016/j.ajog.2020.02.050.
ix Dave, V.P., Ngo, T.A., Pernestig, AK. et al. MicroRNA amplification and detection technologies: opportunities and challenges for point of care diagnostics. Lab Invest 99, 452–469 (2019). https://doi.org/10.1038/s41374-018-0143-3
x Huang Liujing, et al. Gut Microbiota Exceeds Cervical Microbiota for Early Diagnosis of Endometriosis. Frontiers in Cellular and Infection Microbiology. VOL.11, 2021, https://www.frontiersin.org/article/10.3389/fcimb.2021.788836