What are the imaging methods for detecting deep pelvic Endometriosis? Which is the best one?

The main imaging methods for the detection of deep pelvic endometriosis are Magnetic Resonance Imaging and transvaginal and abdominal Pelvic Ultrasound with intestinal preparation. Both methods are complementary and there is no better one, so although both present high sensitivity and specificity when performed in isolation, these indices increase when both methods are performed in combination. 

Is the diagnosis of pelvic Endometriosis done by imaging tests?

The diagnosis of pelvic endometriosis is not done by imaging exams but by clinical exams, especially in patients with severe menstrual cramps (dysmenorrhea), chronic pelvic pain, changes in bowel and urinary habits during menstrual periods, dyspareunia (pain during or after sexual intercourse) and infertility, among other symptoms.

Why performing imaging tests on clinical suspicion of pelvic Endometriosis?

Imaging tests, when performed in appropriate high resolution equipment and interpreted by specialized and experienced medical professionals, have high sensitivity and specificity (ranging from 85 to 99% in the literature) for the detection of deep pelvic endometriosis, ovarian endometrioma, pelvic adhesions and other pathologies that may be associated. On the other hand, they have low sensitivity for detecting the superficial form of endometriosis, and the normal examination does not exclude the possibility of the disease.

So we can say that:

• They assist in confirming the clinical suspicion of the disease.
• They allow the identification of patients with more severe disease conditions (deep endometriotic implants, ovarian endometriomas, pelvic adhesions) which may require a highly complex surgical treatment with a multidisciplinary team.
• They permit follow-up of the disease in patients who are undergoing clinical or postoperative treatment.
• They detect other pelvic pathologies that may be associated with endometriosis.

Why performing bowel preparation in imaging tests for the detection of deep pelvic Endometriosis?

Intestinal preparation performed for the imaging exams of the female pelvis (Magnetic Resonance and abdominal and transvaginal US) significantly increases the sensitivity for the detection of deep pelvic endometriosis.

This is because intestinal preparation significantly reduces the presence of fecal residues and intestinal gases that are limiting to imaging studies, generating artifacts and often preventing visualization of structures located adjacent to or behind the ultrasound method. This way, it allows a better evaluation of the walls of the intestinal loops, especially of the rectosigmoid (where about 80 to 90% of the deep intestinal implants of endometriosis are located), cecum, ileal loops and cecal appendix, as well as determining a better definition of the other structures of the pelvic cavity.

With the “clean” intestine, ultrasound examinations for screening deep pelvic endometriosis can be performed more easily, in less time, generating less discomfort to the patient and greater sensitivity in the various places where the disease may be present, especially the intestine.

For magnetic resonance imaging, in addition to preparing for intestinal cleaning, it is important to administer antispasmodic drugs intravenously before the beginning of the examination, which reduces the movement of the intestinal loops (peristalsis) that determine artifacts in the image (blurring of the contour of the intestinal loops and adjacent structures). In addition, we suggest the use of saline solution rectally to better define the intestinal contour, increasing sensitivity in the detection of deep intestinal endometriotic implants, which can range from a few millimeters to several centimeters.

Dr. Carlos Henrique Trippia (Brazil)

Female pelvic imaging specialist, Endometriosis specialist, Abdominal Radiologist.