Imaging In Practice

Role of imaging in endometriosis

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ABSTRACTEndometriosis—the presence of endometrial tissue outside the uterine cavity—is first suspected on the basis of its signs and symptoms. The diagnosis is confirmed by imaging and surgery. Imaging, particularly transvaginal ultrasonography and magnetic resonance imaging, is essential to confirm the diagnosis and guide surgical treatment.


  • The diagnostic evaluation should always start with transvaginal ultrasonography of the pelvic structures followed by magnetic resonance imaging, especially if deeply infiltrating endometriosis is suspected.
  • An inaccurate imaging evaluation may lead to an incomplete excision of lesions if the patient undergoes surgery.
  • Transvaginal ultrasonography and magnetic resonance imaging allow the assessment of the size, location, and extent of the lesions.
  • Given the multifocal nature of the disease, a thorough evaluation of all pelvic structures, including the bowel, the bladder, and the ureters, is always recommended.



A 32-year-old woman presents with a history of pelvic pain, dysmenorrhea, dyspareunia, dyschezia, and dysuria, with exacerbation of the symptoms during her menstrual cycles. Her menarche occurred at the age of 13 and her menses are regular. She has never undergone surgery and has no relevant pathologic processes. She also reports that for the past 18 months she has been unsuccessfully trying to conceive.

Two months ago, she went to the emergency department because of an acute episode of severe pelvic pain associated with abdominal cramps, vomiting, and dyschezia, occurring at the beginning of her menstrual cycle. At that time, her vital signs were within normal limits, but deep palpation of the right iliac fossa was painful. On that occasion, acute abdomen and bowel obstruction were excluded.

Now, vaginal examination reveals a bluish, painful, bulky induration in the posterior fornix. Digital rectal examination reveals a circular infiltrated area in the anterior rectal wall. Her cancer antigen 125 (CA 125) level is 230 U/mL (normal range 0–35 U/mL).


The diagnosis of endometriosis should be considered in the patient described above. Many of her signs and symptoms can be associated with several diseases. However, the diagnostic hypothesis points strongly toward endometriosis, since her symptoms recur at the beginning of every menstrual cycle.1

Endometriosis is the presence of endometrial tissue outside the uterine cavity. The affected organs usually include the ovaries, fallopian tubes,2 peritoneal surface, vagina, cervix, abdominal wall,3 scar tissue, pouch of Douglas, urinary tract, and bowel. However, any organ can be involved.

So-called deeply infiltrating endometriosis is an endometriotic lesion penetrating into the retroperitoneal space (most often affecting the uterosacral ligaments and the rectovaginal septum) or the pelvic-organ wall to a depth of at least 5 mm and involving structures such as the rectum, vagina, ureters, and bladder.4 Its clinical presentation is highly variable, ranging from no symptoms to severe pain and dysfunction of pelvic organs.

Endometriosis can be diagnosed with certainty only when the endometriotic lesions are observed by laparoscopy or laparotomy and after the histologic examination of surgically resected lesions (Figure 1).1 However, a presumptive diagnosis can be made on the basis of imaging findings, which can be useful in the differential diagnostic process (Table 1).

Figure 1. Diagnostic algorithm for endometriosis.


Knowing the history of the patient, along with a physical examination that includes speculum and bimanual vaginal and rectal examination, can be helpful in the diagnostic process even if nothing abnormal is found.

Pelvic examination has a poor predictive value, as demonstrated in a study conducted by Nezhat et al5 in 91 patients with surgically confirmed endometriosis, 47% of whom had a normal bimanual examination.

CA 125 is the serologic marker most often used for diagnosing endometriosis. Levels are usually high in the sera of patients with endometriosis, especially in the advanced stages.6 However, levels increase both in the physiologic menstrual cycle and in epithelial ovarian cancers.7 Thus, the diagnostic value of CA 125 is limited in terms of both sensitivity and specificity.

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