The presence of endometrial tissue, including the stroma and glands outside the uterus, is called endometriosis. Due to the association of the disease with estrogen in the body, endometriosis is mainly observed in women of childbearing age and sometimes in adolescents and postmenopausal women undergoing hormone replacement therapy (1, 2, 3, 4). About 10% of women of childbearing age suffer from endometriosis, which causes dysmenorrhea, dyspa-reunia, chronic pelvic pain, and infertility (5, 6, 7). Endometriosis is a benign disease of women that often presents with pelvic pain and infertility (7, 8).
About 17 to 44% of patients with endometriosis have ovarian endometrioma (5, 7, 8). Ovarian endometrioma is one of the most common causes of pelvic pain and one of the most common ovarian cysts that we encounter during surgery (8, 9, 10). There is much speculation about the pathogenesis of endometriosis, but most studies support the theory that the disease is caused by the implantation of endometrial cells returned from the fallopian tubes into the abdominal cavity (11, 13).
One of the diagnostic methods of endometriosis is to use laparoscopy and see endometriotic areas and finally histological examination of these areas. Sur-geons and patients are more inclined to laparoscopic treatment rather than open surgery because it is a faster and less invasive procedure. Laparoscopic treatments include endometrioma aspiration, laparoscopic cystic-tomy, cyst drainage, and catheterization or laser, and even more radical treatments such as removal of part or all of the ovary and sometimes with uterine appendages (12, 13).
Although laparoscopy is the standard diagnostic method for endometriosis, possible complications in laparoscopic treatment include possible damage to other organs by laparoscopic devices, while the risk of infection, bleeding, postoperative illness, long-term hospitalization, ileus, deep vein thrombosis and other medical problems following laparotomy are common (14, 15, 16) . Laparoscopic treatment is also expensive and carries the risk of surgery (17).
Visual examination of the pelvis, as well as limitations such as the diagnosis of posterior pelvic, intestinal, and bladder involvement in endometriosis have led to the significant use of imaging techniques to treat and diagnose the disease. The advantages of using imaging techniques in the diagnosis of endometriosis include greater availability and acceptance for women and quick and cost-effective conclusions compared to surgical procedures. However, imaging methods depend on the skill of the operator and the extent of access to proper radiology facilities (18, 19).
Transvaginal ultrasound and MRI imaging are widely used in the diagnosis of deep lesions and recto-sigmoid involvement. Transvaginal ultrasound is useful in the diagnosis of ovarian endometrioma if the diameter is larger than 2 cm (18, 20). MRI and US ima-ging (including transabdominal, transvaginal, and transrectal) are the most common diagnostic methods for endometriosis (21, 22, 23). Transvaginal ultrasound is more useful in diagnosing endometriosis than other ovarian cysts (24, 25).
MRI imaging is used in the diagnosis of deep endometriosis lesions and is more effective than other methods in the diagnosis of small lesions (18, 20). Due to the importance of pelvic endometriosis, its comp-lications such as pain and infertility (26) and the limited number of studies on this disease in Iran, in this study, we have evaluated the diagnostic value of TVS (Tran-svaginal sonography) in the diagnosis of pelvic endometriosis compared with laparoscopic evaluation in patients referred to the imaging center of Imam Khomeini Hospital and Yas Hospital of Tehran in 2018.

Table 1. Comparison of the frequency of DIE based on the location of ultrasound and laparoscopy in patients

In the anterior compartment, 15.9% of the bladder base, 1.4% of the bladder dome, 2.9% of the distal ureter; In the posterior compartment, 8.7% of the rectovaginal septum, 42% of the uterosacral ligament, 4.3% of the posterior vaginal fornix, 29% of the torus uterinus, 8.7% of the lower rectum, 18.8% of the upper rectum, 26.1% of the rectosigmoid; in 4.3% of cases peritoneal cysts were seen. The frequency distribution of the site of involvement as DIE nodules in laparoscopy was reported in 63.8% of patients, which are as follows; In the anterior compartment 2.9% of the bladder trigone, 20.9% of the bladder base, 11.6% of the blad-der dome, 14.5% of the distal ureter; In the posterior compartment 10.1% rectovaginal septal involvement, 47.8% uterosacral ligament, 5.8% posterior vaginal fornix, 24.6% torus uterinus, 8.7% lower rectum, 11.6% upper rectum, 58% rectosigmoid, 1.4% of the sigmoid colon and 18.8% of peritoneal cysts were reported.
The mean size of endometriotic nodules varied from 12.7 to 25.6 mm in the patients examined based on ultrasound.
Regarding various findings (Table 2) in patients, the sensitivity and specificity of ultrasound in the diag-nosis of adhesion based on the sliding sign were:  in the anterior compartment 33.3% and 53%, and in the posterior compartment 7.1% and 92.7% (including 71.4% and 65.5% in retro cervix And 60% and 86.4% in posterior fundus). Also, the sensitivity and specificity of sonography in diagnosing unilateral endometrium was 83.3% and 90.2%, bilateral endometrium 93.3% and 76.9%, decreased left ovarian mobility 50% and 92.3%, fixed left ovarian mobility 88.5% and 74.4%, decreased right ovarian mobility 100% and 89.6%, fixed right ovarian mobility 84% and 72.7%, diffuse pelvic adhesion 90.2% and 55.6%, and Kissing ovaries 81.8% and 74.5%.
 

Table 2. Comparison of ultrasound and laparoscopic results of patients

Ultrasonic and laparoscopic consistency in the diagnosis of adhesions is as follows, in the anterior compartment 52.2%, in the posterior compartment 75.4% (including 66.7% in the retro cervix, 82.6% in posterior fundus), unilateral endometrium 82.6%, bilateral endometrium 84.1%, decreased left ovarian mobility 89.6%, fixed left ovarian mobility 79.7%, decreased right ovarian mobility 89.6%, fixed right ovarian mobility 76.8%, diffuse pelvic adhesion 81.2% and 76.8% was related to kissing ovaries.
In this study, the sensitivity and specificity of ultra-sound in the case of DIE detection (Table 3) as nodules were 88.6% and 60%, single involvement 52.2% and 71.7%, multiple involvement 54.3% and 76.5%, anterior compartment involvement including bladder base 64.3% and 96.4%, bladder dome 87.5% and 100%, distal ureter 10% and 98.3% and posterior compartment involvement including rectovaginal septum 42.9% and 95.2%, uterosacral ligament 75.8% and 88.9%, posterior vaginal fornix 25% and 96.9%, Torus uterinus 94.1% and 92.3%, Lower rectum 50% and 95.2%, Upper rectum 62.5% and 86.9%, Rectosigmoid 42.5% and 96.6%, accompanying findings such as peritoneal cyst 23.1% and 100% and tubal involvement were 43.8% and 67.6%. Ultrasound has indefinite sensitivity in the diagnosis of bladder trigone and sigmoid colon involvement but has 100% specificity.

 Table 3. Comparison of involvement site in ultrasound and laparoscopy of patients

Ultrasonic and laparoscopic compatibility of DIE detection as nodules were 78.3%, single involvement 65.2%, multiple involvement 65.2%, anterior compartment involvement including bladder trigone 97.1%, bladder base 89.9%, bladder dome 89.9%, distal ureter 85.5 %, Posterior compartment involvement including rectovaginal septum 89.9%, uterosacral ligament 82.6%, posterior vaginal fornix 92.7%, torus uterinus 92.7%, lower rectum 91.3%, upper rectum 84.1%, rectosigmoid 65.2%, sigmoid colon 98.6%. Accompanying findings such as peritoneal cyst was 85.5% and tubular involvement was 56.5%.