Does Endometriosis Show Up on Ultrasound? A Guide to Ultrasound, MRI and Laparoscopy
Key Takeaways
Yes — some forms of endometriosis can be seen on ultrasound, especially ovarian endometriomas and many deep lesions, when an experienced operator uses the four-step IDEA protocol. Superficial peritoneal disease may still be missed, so a normal scan does not rule the condition out. MRI helps when ultrasound is inconclusive. CA-125 is not for screening or routine monitoring. Laparoscopy is no longer an automatic first step under ESHRE 2022 and NICE 2024.
Key evidence: ESHRE guideline: endometriosis (2022) NICE NG73 — endometriosis diagnosis (updated 2024) IDEA protocol — Guerriero et al., 2016
On this page
- Does endometriosis show up on ultrasound?
- Diagnosis starts before the scan: symptoms and examination
- When to seek prompt assessment
- Transvaginal ultrasound following the IDEA protocol
- Pelvic MRI: When and Why
- CA-125: Not for Screening or Routine Monitoring
- The New Place of Laparoscopy
- Does Suspected Endometriosis Change the Infertility Work-Up?
- Pitfalls and Limits to Keep in Mind
- In Practice
- FAQ
- Clinical Note
Does endometriosis show up on ultrasound?
Yes — specific forms of endometriosis can be identified on ultrasound. Ovarian endometriomas and deep infiltrating lesions often show up clearly when evaluated using structured scanning protocols. However, superficial peritoneal lesions usually remain invisible. A normal ultrasound scan does not rule out endometriosis.
Historically, diagnostic laparoscopy was viewed as the only definitive diagnostic tool. Waiting for surgery contributed to significant diagnostic delays, alongside normalized period pain and delayed specialist referrals. Diagnostic delay remains common worldwide across different health systems.
The ESHRE 2022 guideline established high-resolution imaging as the primary diagnostic step, reserving surgery for cases where it directly alters treatment. The objective is clear:
- Shorten time to diagnosis.
- Avoid unnecessary surgical procedures.
- Initiate symptom-focused care earlier.
- Tailor pathways specifically for pain management or fertility goals.
For comprehensive details, review the complete endometriosis guide, endometriosis and infertility, and endometriosis symptoms.
Diagnosis starts before the scan: symptoms and examination
Specialist imaging complements clinical evaluation and symptom history.
Key clinical indicators include:
- Progressive or worsening period pain (dysmenorrhea).
- Deep pelvic pain during intercourse (dyspareunia).
- Cyclic bowel pain or painful bowel movements (dyschezia).
- Cyclic urinary pain or blood in urine (dysuria/hematuria).
- Chronic pelvic pain and chronic fatigue.
- Unexplained infertility or a family history of endometriosis.
Clinical examination may reveal a fixed retroverted uterus, tenderness in the posterior fornix, or palpable adnexal masses. A normal pelvic examination does not exclude disease. NICE recommendations advise offering pelvic ultrasound whenever endometriosis is clinically suspected.
When to seek prompt assessment
Immediate medical evaluation is necessary if any of the following acute symptoms occur:
- Sudden severe unilateral pelvic pain.
- Fainting, dizziness, or signs of internal bleeding.
- Pelvic pain accompanied by a positive pregnancy test.
- High fever or signs of acute pelvic infection.
- Rapidly enlarging ovarian mass or postmenopausal pelvic bleeding.
- Symptoms of acute bowel obstruction or severe urinary blockage.
Transvaginal ultrasound following the IDEA protocol
The IDEA protocol (International Deep Endometriosis Analysis), developed by Guerriero et al. in 2016, structures pelvic ultrasound into four systematic steps. Imaging findings can also be mapped using the #Enzian classification system.
If transvaginal ultrasound is not clinically appropriate or accepted, transabdominal ultrasound is performed first, followed by MRI if needed.
Step 1 — Uterus and Adnexa
The examiner assesses:
- Uterine mobility: Evaluation of uterine flexibility and retroversion.
- Adenomyosis markers: Asymmetric wall thickening, myometrial cysts, and subendometrial lines.
- Ovarian endometriomas: Identification of “ground-glass” fluid-filled ovarian cysts.
- Antral Follicle Count (AFC): Measured when fertility planning is required.
An endometrioma finding does not automatically require surgical removal. Age, AMH levels, symptoms, and IVF plans must be reviewed first.
Step 2 — Soft Markers
Two indirect physical signs are evaluated:
- Site-specific tenderness: Pain triggered by light probe pressure over ovaries or pelvic structures.
- Ovarian fixation: Absence of normal sliding movement between the ovary and pelvic sidewall.
Step 3 — Sliding Sign
Dynamic abdominal pressure checks whether the uterus glides smoothly over the rectum in the Pouch of Douglas.
- Positive sliding sign: Normal gliding motion indicating the Pouch of Douglas is open.
- Negative sliding sign: Restricted movement indicating partial or total pouch obliteration.
Step 4 — Anterior and Posterior Compartments
Systematic evaluation for deep hypoechoic nodules:
- Anterior compartment: Bladder wall and vesico-uterine pouch.
- Posterior compartment: Uterosacral ligaments, rectovaginal septum, and rectosigmoid colon.
Diagnostic Performance
Transvaginal ultrasound is highly accurate for ovarian endometriomas, and expert scanning identifies rectosigmoid deep lesions with high precision. However, superficial peritoneal lesions remain invisible on routine scans. Normal imaging cannot rule out superficial disease.
Pelvic MRI: When and Why
Pelvic MRI is indicated under specific circumstances:
- Ultrasound results are inconclusive despite persistent symptoms.
- Deep lesions require precise surgical mapping involving the bowel, bladder, or ureters.
- Discrepancies exist between clinical examination and ultrasound findings.
- Transvaginal imaging is not clinically appropriate.
Specialist MRI and expert ultrasound are complementary diagnostic tools. Both are limited in detecting superficial peritoneal implants.
CA-125: Not for Screening or Routine Monitoring
CA-125 is a non-specific blood biomarker. It may rise in endometriosis, but it also increases during menstruation, pregnancy, pelvic infections, fibroids, or functional cysts.
ESHRE 2022 guidelines recommend against using CA-125 for screening, diagnosis, or routine monitoring of endometriosis.
The New Place of Laparoscopy
Diagnostic laparoscopy is no longer the mandatory first-line diagnostic step. ESHRE guidelines no longer classify it as an automatic default.
When Laparoscopy Is Considered
- Normal imaging results in patients with severe pain unresponsive to medical therapy.
- Surgical intervention is required to remove painful lesions or excise deep nodules.
- Specific, complex infertility scenarios require direct surgical evaluation.
When Laparoscopy Is Not Indicated
- As a mandatory requirement prior to starting medical pain management.
- As a routine screening tool in asymptomatic patients.
- As a reflex response to pelvic pain before non-invasive options are explored.
Empirical Treatment: For Pain — Not While Trying to Conceive
Empirical medical therapy (analgesics, combined hormonal contraceptives, or progestins) can be initiated when imaging is normal and pain relief is the primary goal.
If pregnancy is desired: Empirical hormonal suppression blocks ovulation and does not improve fertility. If actively trying to conceive, age, ovarian reserve, tubal patency, and male factor parameters must be evaluated without delay.
Does Suspected Endometriosis Change the Infertility Work-Up?
AMH and antral follicle counts assess ovarian reserve, not endometriosis diagnosis. Basic fertility evaluations—including tubal testing and semen analysis—should proceed without delay.
Diagnostic laparoscopy is not routinely performed for infertility if imaging and tubal testing are normal. Decisions depend on age, ovarian reserve, pain severity, duration of infertility, and whether IVF is indicated.
Clinical Note
Surgery should be recommended only if findings directly alter the pathway to pregnancy.
In younger patients with good ovarian reserve and significant pain, surgery may support spontaneous conception.
In older patients or those with low reserve, diagnostic surgery can cause unnecessary delay.
Dr. Senai Aksoy
Pitfalls and Limits to Keep in Mind
- Invisible superficial disease: Normal scans do not rule out peritoneal implants.
- Normal exam limits: Physical examination can be normal in early or superficial disease.
- Operator dependency: IDEA ultrasound accuracy depends heavily on specialized sonographer training.
- Coexisting adenomyosis: Frequently coexists with endometriosis and requires dedicated evaluation.
In Practice
- Start with detailed clinical history and an IDEA-protocol transvaginal ultrasound.
- Order pelvic MRI when deep disease mapping is required or ultrasound is inconclusive.
- Avoid ordering CA-125 for routine screening or monitoring.
- Prioritize fertility assessments over hormonal suppression when pregnancy is the goal.
- Reserve laparoscopy for therapeutic indications or selected complex cases.
FAQ
Does endometriosis show up on ultrasound?
Often yes — especially ovarian endometriomas and many deep lesions — when a trained operator uses the IDEA protocol. Ultrasound may miss superficial peritoneal lesions. A normal scan does not close the case if symptoms remain strong.
Does a normal ultrasound rule out endometriosis?
No. Ultrasound may miss superficial disease and early lesions. If symptoms remain suggestive, specialist imaging, a fertility-focused work-up, or — when pregnancy is not the goal — an empirical pain-control trial may be discussed before writing the problem off.
Should ultrasound be performed during menstruation?
No. An IDEA-protocol ultrasound can generally be performed at any stage of the menstrual cycle. There is no strict cycle window required for a reliable examination, although timing may be adjusted for comfort, bleeding or local practice.
Why is my doctor not ordering CA-125?
Because it does not usefully screen, confirm, exclude or routinely monitor endometriosis. It is often normal early on, and it rises in many unrelated situations. ESHRE 2022 advises against biomarkers such as CA-125 in this diagnostic context.
Is MRI systematic after ultrasound?
No. If IDEA ultrasound is conclusive — a clear endometrioma, clear deep signs, or a reassuring scan that fits the clinical picture — MRI is not mandatory. It helps when ultrasound is inconclusive, when deep disease is suspected, or when a multidisciplinary plan needs more detail.
Will I need a laparoscopy to confirm the diagnosis?
Not routinely. Guidelines avoid automatic diagnostic laparoscopy. It may still be considered if imaging is negative despite strong ongoing suspicion, if empirical treatment has failed or is unsuitable, or if surgery is independently needed for pain, deep disease or a selected infertility scenario.
How long does diagnosis take?
With a coordinated pathway — a clinician familiar with endometriosis, an experienced sonographer, MRI when needed — a working diagnosis can emerge within weeks. Delay remains a global problem. If symptoms persist, it is reasonable to ask for a systematic evaluation rather than waiting indefinitely.
Sources
- Becker CM, Bokor A, Heikinheimo O, et al. ESHRE guideline: endometriosis. Human Reproduction Open 2022;2022(2):hoac009.
- National Institute for Health and Care Excellence. Endometriosis: diagnosis and management (NG73). Updated 2024.
- Guerriero S, Condous G, van den Bosch T, et al. Systematic approach to sonographic evaluation of the pelvis in women with suspected endometriosis (IDEA consensus). Ultrasound Obstet Gynecol 2016;48:318–332.
- Kanti FS, Gorak Savard R, Bergeron F, et al. Transvaginal ultrasound and magnetic resonance imaging in the diagnosis of endometrioma: a systematic review and meta-analysis. J Obstet Gynaecol 2024;44(1):2311664.
- Xu Z, Li Y, Wang Y, Wan Y, Chen J. Transvaginal ultrasound and magnetic resonance imaging in detecting rectosigmoid deep infiltrating endometriosis: a comparative meta-analysis. Frontiers in Medicine 2025;12:1552185.
- Keckstein J, Saridogan E, Ulrich UA, et al. The #Enzian classification: A comprehensive non-invasive and surgical description system for endometriosis. Acta Obstet Gynecol Scand 2021;100:1165–1175.
- De Corte P, Klinghardt M, von Stockum S, Heinemann K. Time to Diagnose Endometriosis: Current Status, Challenges and Regional Characteristics — A Systematic Literature Review. BJOG 2025;132:118–130. doi:10.1111/1471-0528.17973.
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The content has been created by Dr. Senai Aksoy and medically approved.