Uterine adhesions (IUA) refer to the adhesions of the cavities of the uterus, including the uterine cavity, the isthmus and the cervical canal, caused by surgical operations on the uterine cavity or by radiation or infection.
Etiology
Any factor that causes endometrial destruction can lead to adhesions of the anterior and posterior walls of the uterus. They can be divided into causative factors and pathogenic factors.
1.Predisposing factors
(1) Factors related to pregnancy.
(1) Pregnancy Pregnant uterus is a highly susceptible factor for adhesions to occur. Pregnancy makes the uterus soft, and it is difficult to control the depth when scraping the uterus, which may damage the basal endometrium that has the ability to regenerate.
②Audited abortion Endometrial fibrosis may be associated with placental remnants and villi components who contribute to increased fibroblast activity and collagen formation prior to endometrial regeneration, which may underlie the formation of IUA after curettage for audited abortion. Studies have shown that at least in some patients with endometrial fibrosis, there is an occlusive injury of the uterine artery vasculature, which, while causing a lack of endometrium, also makes the endometrium unresponsive to estrogenic stimulation.
(2) Infection : Infection, especially subacute infection, is the main causative factor for uterine adhesions.
(3) Physical factors : In addition to the above mentioned susceptibility factors, there are individual differences, because after undergoing the same surgical operation, some patients form severe IUA, while others do not form IUA.
2.Causal factors
(1) scraping: 66.7% of IUA reported so far is caused by scraping after abortion or spontaneous abortion, another factor is postpartum hemorrhage scraping, cesarean section and gravida clearance can also cause IUA, but the proportion is very small, so the scraping of the pregnant uterus is considered the main causative factor, if the second to fourth week after delivery, the incidence of IUA is high. If the trauma occurs within 1 week after delivery or after 4 weeks, the incidence of IUA is lower, and adhesions rarely occur when the uterus is scraped within 48 hours after delivery.
(2) Genital tuberculosis Chronic tuberculosis infection of the endometrium is usually caused by systemic transmission of extra-genital tuberculosis or by direct spread of tubal tuberculosis. Severe tuberculosis infection may result in complete loss of the endometrium, with the ultimate consequence of severe IUA, often leading to complete uterine occlusion.
Diagnosis
The diagnosis of uterine adhesions can be clarified by the following methods in addition to the medical history and clinical manifestations.
1.Uterine exploratory surgery
Patients with high suspicion of IUA can be examined with a probe after sterilization. If there are adhesions in the cervical canal or the endometrium, the probe can encounter resistance after entering the cervical canal for 3cm-5cm and it is difficult to penetrate into the uterine cavity; if there is IUA, there can be narrowing and asymmetry when the probe examines the uterine cavity. Since this procedure requires high surgical skills and experience, it is a “blind probe” with poor repeatability and intuitiveness, and its reliability varies from person to person, so it is generally not used as a routine diagnostic tool in clinical practice.
2. Hysterosalpingography with iodine (HSG)
Before the introduction of hysteroscopy, the diagnosis and localization of IUA mainly relied on HSG. Positive radiographic signs can be obtained for most IUA, including filling defects with irregular margins, uterine cavity deformation or irregularity, etc. Filling defects can appear anywhere in the uterine cavity, sometimes crescent-shaped, sometimes oddly shaped, and usually the filling defects do not change with increasing pressure and amount of contrast, but sometimes during HSG procedure may separate the fibrous membrane-like adhesions. In addition, HSG often fails in cases of complete uterine atresia or cervical isthmus adhesions, because in these patients the uterine orifice disappears or becomes pinhole-sized and cannot be passed even with the thinnest probes.
3. Vaginal ultrasound (TVS)
It is a simple and easy non-invasive diagnostic technique that saves time, is painless and does not require anesthesia, and has been gradually accepted by health care professionals. In recent years, the clinical use of TVS to diagnose uterine cavity diseases has made great progress, because the ultrasound probe is closer to the female internal genitalia, and thus the images obtained are clearer than traditional transabdominal ultrasound.
4.Hysteroscopy
Hysteroscopy has greatly improved the ability to diagnose IUA. Hysteroscopy can observe the presence of uterine adhesions as well as the location, type and degree of uterine adhesions under direct vision, so hysteroscopy is more accurate in the diagnosis of IUA compared with HSG.
Types of IUA Hysteroscopy can classify IUA into simple cervical adhesions, cervical and uterine cavity adhesions and uterine cavity adhesions according to the site of adhesions, and the latter can be divided into central, peripheral and mixed types according to the location of the adhesions.
(1) Central adhesions: The adhesion zone is located between the anterior and posterior walls of the uterus, which partially adheres to the uterine cavity, and this type of adhesions should be distinguished from longitudinal uterine septum.
(2) Peripheral adhesions: the adhesion zone is located at the bottom of the uterus or in the lateral wall of the uterus, and the peripheral part of the uterine cavity is adhered, especially in the uterine horn, so that the horn of the uterus is occluded and the mouth of the fallopian tube cannot be seen.
(3) Mixed adhesions: central type plus peripheral type adhesions.
5. Hysterosonography (SHSG)
Due to the lack of intrauterine contrast in TVS and the lack of specificity for some intrauterine lesions, the ultrasonographic method of injecting liquid (usually saline) into the cavity has been used. Due to the injection of liquid, the uterine cavity is dilated and the control is increased so that the intrauterine structures can be observed more clearly. However, SHSG examination cannot be used in patients with complete intrauterine adhesions, as injection of medium into the uterine cavity of patients with complete adhesions is not possible.
6.Intrauterine ultrasound (IUS) with high-frequency microprobe
The use of IUS to diagnose intrauterine lesions can obtain a higher definition than TVS and can clearly describe the cyclically changing endometrium, endometrial polyps, uterine adhesions and uterine longitudinal septum, etc. However, the beam penetration depth of this high-frequency probe is only 2-3 mm, so the use of IUS can only be limited to close to the abnormal area or inside the area, while this invasive procedure requires aseptic conditions, and therefore This invasive procedure requires aseptic conditions and therefore can only be used as an important addition to the diagnosis of gynecological diseases.
In conclusion, scraping of the pregnant uterus is the main causative factor of IUA, especially after an abortion, and the influence of genital tuberculosis on uterine adhesions is certain, while other types of trauma, infections and individual differences play a role in the aetiology of IUA. The exact pathogenesis of IUA is still not fully understood and further clinical and laboratory studies are needed. In addition to detailed medical history and physical examination, the traditional methods of diagnosis of IUA are mainly based on hysteropexy and hysterosalpingography with iodine oil. The diagnostic methods have been greatly improved, providing clinical workers with a variety of perfect tests and diagnostic methods, bringing the gospel to the majority of patients.