Endometriosis (endometriosis) is divided into four types according to clinicopathology.
(1) peritoneal-type endometriosis.
(2) Ovarian-type endometriosis.
(3) deep infiltrative endometriosis.
(4) other sites of endometriosis (including gastrointestinal, urinary, and respiratory endometriosis, scar endometriosis, and other rare distant endometriosis, etc.) Koninckx first introduced the concept of deep-infiltrating endometriosis in 1992, and in 2006 [2], the specification for the diagnosis and treatment of endometriosis developed by the Collaborative Group on Endometriosis of the Chinese Medical Association’s Obstetrics and Gynecology Branch defined deep-infiltrating endometriosis as Endometriosis is defined as a lesion infiltrating to a depth of ≥5 mm, commonly found in the uterosacral ligament, the rectal recess, the vaginal fornix, and the rectovaginal septum. One is pseudovaginal-rectal septal endometriosis, in which the adhesions of the rectal fossa are closed and the lesion is located below the adhesions; the other is true rectovaginal septal endometriosis, in which the lesion is located outside the peritoneum, within the rectovaginal septum, with no obvious anatomic abnormalities in the recto-uterine sulcus. The above definitions actually refer to DIE in a narrow sense, while DIE in a broad sense refers to all endometriosis in which the lesions infiltrate to a depth of ≥5 mm below the peritoneum, and the lesions may be located in different parts of the pelvic and abdominal cavities, including endometriosis of the uterosacral ligament, utero-rectal sulcus, vaginal-rectal septum, endometriosis of the bladder and ureter, endometriosis of the rectum, sigmoid colon, and small intestine, endometriosis at the diaphragm and liver, etc. The clinical typing of DIE is confusing, and there is no universally accepted clinical typing so far.
Clinical symptoms of DIE.
Most DIE coexists with other types of ectopic disorders. Pain and infertility are the main symptoms of DIE. The site and nature of pain are related to the distribution and extent of the lesion, and other symptoms vary depending on the site and extent of the lesion. Pain can manifest as severe dysmenorrhea, deep intercourse pain, chronic pelvic pain, and painful defecation. The pain level is three to five times higher than that of the superficial peritoneal and ovarian types due to lesions invading the uterosacral ligament, vaginal vault, vaginal rectal septum, or rectum. Gastrointestinal and urinary tract endothelia can have corresponding symptoms. Endothelia lesions that attack and compress the rectum and colon can cause abdominal cramps, periodic constipation or diarrhea, flatulence, and a feeling of urgency; lesions that attack the intestinal mucosa can cause periodic blood in the stool; lesions that are severe can lead to intestinal obstruction, but not all patients with gastrointestinal endothelia will have gastrointestinal symptoms. Urinary tract endoheterosis can attack the urethra, bladder, ureter, and even involve the kidneys, and bladder and ureter endoheterosis are common. When the lesion invades the bladder, pain in the bladder area and urinary tract irritation symptoms related to the menstrual cycle will occur, such as frequent urination, urinary urgency, and difficulty in urination; if the lesion compresses the ureter, ureteral obstruction and hydronephrosis will occur, there may be pain in the affected side of the lower back and increased blood pressure; when the lesion invades the mucosa of the bladder and ureter, recurrent menstrual hematuria will occur; endo-ureteric disease of the kidney is relatively rare and the symptoms are the most insidious, with menstrual back pain and hematuria are predominant.
Signs of DIE.
During gynecologic examination, a purplish nodule is seen in the posterior fornix, which is a typical feature of DIE, but in some patients the lesion is not typical. Painful nodules may be palpated in the fornix on transvaginal duplex examination, and asymmetric thickening, stiffening and tenderness of the uterosacral ligament may also be palpable; if necessary, the presence of nodular lesions may be more clearly palpable on triple examination, but not all patients with DIE have positive gynecologic findings. The patient’s uterus is mostly posterior and poorly mobile. In patients with combined ovarian-type ectopic disease, a mass in the adnexal region may be palpable, with adhesions to the uterus and surrounding areas. Menstrual gynecological examination will improve the accuracy of the diagnosis of DIE, but menstrual gynecological examination can cause a medical source of disease and should only be performed with the patient’s knowledge when DIE is highly suspected and the diagnosis needs to be confirmed. The extra-intestinal wall mass or extra-mucosal mass can be palpated during rectal finger examination for lower-positioned intestinal wall endografts, which are obvious to palpation and have smooth and intact mucosa; lesions in higher positions, above the sigmoid colon, cannot be palpated during rectal finger examination. In endometriosis of the bladder, the mass can be palpated between the posterior bladder and the anterior wall of the uterus; in patients with endometriosis of the ureter, which is mostly found with endometriosis of the uterosacral ligament, the utero-rectal sink, and the vaginal rectal septum, asymmetric thickening, stiffening, and palpable nodules of the uterosacral ligament can be palpated; most endometriosis of specific sites cannot be palpated.
Diagnosis of DIE.
The lesions of DIE are mostly diffuse, without clear boundaries between them and normal tissues, and with different morphology, which increases the difficulty of DIE diagnosis, and the rate of leakage and misdiagnosis is also high. It is necessary to make a clinical diagnosis by combining the results of medical history, gynecological examination and auxiliary examinations, etc. There is no uniform clinical diagnostic standard yet, but when the above examination results suggest that the depth of invasion of endometriosis lesions is ≥5 mm, the diagnosis of DIE is considered. Confirmation of the diagnosis of DIE requires surgical and postoperative pathological histological findings.
The patient’s medical history is very important. The patient’s pain (dysmenorrhea p chronic pelvic pain p painful intercourse, etc.) and the degree of dysmenorrhea are mostly related to the degree of lesion, and the degree of pain in patients with DIE is three to five times higher than that in superficial peritoneal and ovarian types. The patient’s menstrual history should also not be ignored. Most patients with DIE have concomitant adenomyosis, and patients also have shortened menstrual cycles, prolonged periods, increased menstrual bleeding and secondary anemia as a result, and patients tend to have severe dysmenorrhea, or lower abdominal pain that worsens during menstruation. The patient’s past history also plays a very important role in the diagnosis of DIE. If the patient has a history of previous endo surgery, or if previous ultrasound repeatedly indicates the presence of ovarian ectopic cysts, or if repeated gynecologic examinations highly suspect the presence of pelvic endo, the combination of gynecologic examinations suggests the presence of DIE.
Careful gynecologic examination is essential in the diagnosis of DIE. Vaginal lesions are mostly present in the posterior fornix, posterior to the cervix, and vaginal lesions are easily missed because of the wide range of DIE lesions and the poor mobility of the uterus. Gynecologic examination (double and triple examination) plays an important role in determining the presence of lesions, understanding the extent of lesions and judging the size of lesions. The main manifestations are painful nodules in the fornix, uterosacral ligament, etc.; endometriosis of the bladder can be palpated in the anterior uterus and posterior bladder; patients with endometriosis of the ureter are mostly found with endometriosis of the uterosacral ligament, uterine rectal sink, and vaginal rectal septum, manifesting as nodules of the uterosacral ligament; other special areas of endometriosis are mostly undetectable and need to be determined by ancillary examinations.
The most commonly used clinical method is transvaginal ultrasonography, pelvic CT and MRI will improve the accuracy of clinical diagnosis of DIE, and for DIE in special areas, relevant special examination will be useful, but there is a lack of a specific DIE auxiliary examination method, and vaginal ultrasonography combined with MRI can improve the detection rate of DIE. The pros and cons of the adjuvant examination methods are analyzed as follows.
1. B-mode ultrasonography.
It is a relatively inexpensive and efficient examination method, including transabdominal ultrasound (TAS), transvaginal ultrasound (TVS), transrectal ultrasound (TRS) and rectal endoscopic ultrasound (EUS). Transvaginal sonography (TVS): A commonly used adjunctive diagnostic method for endorectal disease, DIE presents as an irregular hypoechoic mass with or without a strong echogenic spot reflection. TVS can detect the entire pelvic organs, including the bladder, uterus and its ligaments, rectal trap, both ovaries, vaginal-rectal septum and colorectum. In the absence of sexual intercourse or rectal ectopia, rectal ultrasound (TRS) can be performed, and TRS is superior to TVS in the diagnosis of rectal ectopia. “A small amount of streaky blood flow signal is seen within the mass, which is a low velocity, low resistance arterial spectrum. Ureteral ectasia ultrasound may show only ureteral stenosis, separated and dilated renal pelvis, and hydronephrosis, but no stone echogenicity.
Renal endometriosis ultrasound shows renal occupancy, renal cystic lesions, and hydronephrosis. Rectal endoscopic uhrasonography (RES): It allows direct observation of the morphology of the rectal lumen and simultaneous ultrasound scanning to obtain ultrasound images of the features of the intestinal wall at all levels and the surrounding adjacent organs, compensating for the disadvantage that simple endoscopy can only describe the surface morphology. Ultrasound endoscopy-guided fine-needle aspiration technique can be applied to rectal ectopic biopsy. Abdominal wall incisional ectopia and abdominal lesions need to be identified by abdominal ultrasound (TAS). The sensitivity and specificity of TVS in the diagnosis of DIE were 0.799 and 0.944, TRS was 0.925 and 0.986, and EUS was 0.635 and 0.928, respectively, as shown in the Meta-analysis by Xiufeng Huang et al. The shortcomings of TVS are that it is difficult to assess lesions above the junction of the rectum and sigmoid colon, and the depth of infiltration of the rectal wall cannot be accurately determined; TRUS is less well studied and cannot be better compared with the other two methods; EUS requires bowel preparation and anesthesia and is relatively expensive. In addition, ultrasound results depend on the experience of the ultrasonographer is their common disadvantage.
2. MRI.
MRI imaging features vary depending on the type of lesion, and are more sensitive for the diagnosis of ectopic foci with deep infiltration below the peritoneum and invasion of organs such as the bladder and intestine, but lack sensitivity for the diagnosis of extensive pelvic lesions.MRI shows that DIE lesions rely on hemoglobin in the hemorrhagic foci, and the presence of methemoglobin significantly shortens the T1 time of the fluid, making the tissue high signal in T1-weighted images and high signal in T2-weighted images. MRI is a better adjunct to TVS, TRS and physical examination in determining DIE lesions. MRI is difficult to identify DIE lesions when the hemorrhagic sac is small, or when there is no hemorrhagic sac. In addition, MRI is difficult to identify intestinal nodules with endoheterosis that are more than 8 cm from the anus. Although MRI cannot replace laparoscopy in the final diagnosis and staging of endo-intestinal disease, it has strong advantages in the selection of preoperative laparoscopic procedures and postoperative disease monitoring. Some scholars have reported that the sensitivity and specificity of MRI examination after ultrasound plasma placement in the vagina and rectum can reach 94.11% and 100%, respectively.
3. CT.
Simple CT or the use of intravenous contrast agents often cannot clearly show the morphology of the intestinal canal, especially those without obvious occupying lesions, so the combined application of water enema to distend the intestinal canal is more appropriate. This approach allows the acquisition of multiple enhancement-displayed thin-section images of the colon, with intestinal endometriosis appearing as positively enhanced solid nodules adjacent to or penetrating the thickened bowel wall depending on size and depth of infiltration. Multi-segment CT combined with liquid colon distension (muhislice computed tomography combined with colon distension by water enteroclysis, MSCYe) examination has a sensitivity of 98.7%, specificity of 100%, positive predictive value was 100% and negative predictive value was 95.7%.
4. laparoscopy.
Laparoscopy is currently the “gold standard” for the diagnosis of endometriosis, which allows direct observation of the lesion, staging of r-AFS, and biopsy. However, laparoscopic exploration is limited for diagnostic purposes because deep endometriosis lesions are concealed by adhesions or localized in the subperitoneal space.
5. Other relevant examinations.
(1) Rectosigmoidoscopy can detect whether there is stenosis of the rectum and/or colon and whether the mucosa is invaded. If the mucosa is invaded, a biopsy can be taken for pathological examination to clarify the diagnosis;
(2) Dual air-barium imaging: It can show the morphological changes caused by the outward to inward compression of the intestine, but it does not show the thickness of the intestinal canal itself and the infiltrated lesions, the actual size of the compression lesions, and cannot be distinguished from other occupying lesions;
(3) Cystoscopy can be performed simultaneously with biopsy to exclude the possibility of bladder tumors;
(4) Ureteroscopy can also be performed simultaneously with biopsy, which is more significant for the diagnosis of intraluminal ureteral ectopia;
(5) Intravenous pyelogram can clarify the site of ureteral obstruction;
(6) Renal hemogram can assess the renal function.
6.Serological examination.
(1) CA125 determination.
CA125 is expressed to varying degrees in normal or pathological tissues of Mullerian duct origin, and is especially highly expressed in epithelial ovarian tumors, but its elevated serum levels can also be seen in other benign and malignant diseases or physiological states such as endometriosis, inflammatory reactions and pregnancy states, lacking specificity. The determination of serum CA125 has some clinical significance for the diagnosis of endometriosis. The determination of serum CA125 value of DIE may be elevated, but it is non-specific and can be used to monitor the efficacy of treatment and determine the recurrence of the disease with more clinical value than the diagnosis.
(2) Anti-endometrial antibodies (EMAb).
The incidence of EMAb in patients with endometriosis was found to be 78%~80%, while EMAb was rarely found in the serum or peritoneal fluid of normal women of childbearing age without endometriosis, and its value as an auxiliary diagnostic marker for endometriosis is under further study.
To improve the diagnosis of this disease, it is crucial to enhance the awareness of the disease. Careful medical history should be taken, and the disease should be considered if there is an aggravation of symptoms during menstruation along with pelvic endometriosis. Ultrasound, CT, MRI, etc. done at different times of the menstrual cycle with different manifestations or changes in the lesion will help in the diagnosis.