Causes of Peritoneal Endometriosis

What is peritoneal endometriosis? It is a scar endometriosis formed on the abdominal wall after the endometrium and cesarean section. For this disease, female friends hope that they can detect the disease as soon as possible so that their bodies can be treated as soon as possible. Now, let the experts introduce us to the causes of peritoneal endometriosis. Only by understanding it clearly can we effectively prescribe the right medicine.

1. Causes

Implant theory (30%):

As early as 1921, some people believed that the occurrence of pelvic endometriosis was caused by the backflow of endometrial fragments with menstrual blood, entering the pelvic cavity through the fallopian tubes and implanting in the ovaries or other parts of the pelvic cavity. Clinically, during laparotomy during the menstrual period, menstrual blood can be found in the pelvic cavity, and endometrium can be found in the menstrual blood. The endometriosis of the abdominal wall scar formed after cesarean section is a good example of the implantation theory.

Serous membrane theory (25%):

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Immunology (25%):

In 1980, Weed et al. reported that there were lymphocytes and plasma cell infiltrations around the ectopic endometrium, and macrophages contained hemosiderin deposition and varying degrees of fibrosis. They believed that this was because the ectopic endometrial lesions acted as foreign bodies and activated the body's immune system. Since then, many scholars have explored the cause and pathogenesis of endometriosis from the aspects of cellular immunity and humoral immunity.

(I) Cellular immune function deficiency

(II) Humoral immune deficiency

There are other theories about the occurrence of endometriotic tissue: ① The lymphatic spread theory, which believes that the endometrium can spread through the lymphatic channels. Some people have found that the parametrial lymph nodes and internal iliac lymph nodes contain endometrial tissue, but the weakness of this theory is that endometrial tissue is rarely seen in the center of regional lymph nodes, and the common sites do not conform to normal lymphatic drainage; ② The blood flow spread theory. According to literature reports, ectopic endometrium has been found in veins, pleura, liver parenchyma, kidneys, upper arms, lower limbs, etc. Some scholars believe that the most likely possibility is that the endometrium spreads to the above-mentioned tissues and organs through the blood flow, and has caused experimental endometriosis in rabbit lungs. However, some people believe that although these situations may be caused by hematogenous spread, the factor of local metaplasia cannot be ruled out, because the pleura is also differentiated from the coelomic epithelium. When the germ and mesonephric duct are produced in the embryonic period, the coelomic epithelium may be ectopically located in them. In the future, the tissue may metaplasia and form endometriosis in these parts.

Regardless of the source of the ectopic endometrium, its growth is related to ovarian endocrine system. Clinical data show that this condition mostly occurs in women of childbearing age (over 80% in women aged 30 to 50 years old), and is often complicated by ovarian dysfunction. After ovarian removal, the ectopic endometrium atrophies. The growth of ectopic endometrium mainly depends on estrogen. During pregnancy, the secretion of progesterone is relatively high, and the ectopic endometrium is inhibited. Long-term oral use of synthetic progestins such as ethinyl isoproterenolone can cause pseudopregnancy and also atrophy of the ectopic endometrium.

Pathological changes:

1. Internal endometriosis

The endometrium grows from the base to the myometrium and is confined to the uterus, so it is also called adenomyosis. The ectopic endometrium is often diffused throughout the uterine muscle wall. Due to the invasion of the endometrium, the fibrous tissue and muscle fibers are reactively proliferated, causing the uterus to swell uniformly, but there are rarely cases where the head of the fetus exceeds that of a full-term fetus. Those with uneven or focal distribution are generally more common in the posterior wall. Since it is confined to a part of the uterus, the uterus often enlarges irregularly, resembling a uterine fibroid. The cross-section shows that the proliferating muscle tissue also has a vortex-like structure similar to that of a fibroid, but there is no capsule-like tissue that separates it from the surrounding normal muscle fibers as in a fibroid. There is a softening area in the middle of the lesion, and occasionally scattered small cavities containing a small amount of old blood can be seen. The endometrial glands seen by microscopy are the same as those of the endometrial glands, surrounded by endometrial stroma. The ectopic endometrium changes with the menstrual cycle, but the changes in the secretory period are not obvious, indicating that the ectopic endometrial glands are less affected by progesterone. When conception occurs, the stromal cells of the ectopic endometrium may show obvious decidualization, as mentioned above.

2. Interstitial endometriosis

It is a special type of intrinsic endometriosis, which is less common. That is, the ectopic endometrium only has endometrial stromal tissue, or the scope and degree of development of stromal tissue after the endometrium invades the myometrium far exceeds the glandular components. Generally, the uterus is uniformly enlarged, and the ectopic cells are scattered in the myometrium or concentrated in a certain area. They are yellow in color, often have elastic rubber-like hardness, and are softer than fibroids. Cord-like worm-like protrusions can often be seen on the cut surface, which can be used to establish the diagnosis. Ectopic tissue can also develop into the uterine cavity to form polyp-like masses, which are multiple, smooth in surface, and have wide pedicles and a large area of ​​direct connection with the uterine muscle wall. They can also protrude from the uterine wall into the uterine cavity or along the uterine blood vessels into the broad ligament. Protrusion into the uterine cavity causes menorrhagia or even postmenopausal bleeding; protrusion into the broad ligament can be detected by gynecological bimanual examination. Interstitial endometriosis can have pulmonary dissemination, and it can even occur several years after hysterectomy. Due to this characteristic, some people believe that interstitial endometriosis is a low-level malignant sarcoma.

3. External endometriosis

The endometrium invades tissues outside the uterus (including ectopic endometrium that invades the uterine serosa from the pelvic cavity) or organs, often involving multiple organs or tissues.

The ovaries are the most common site of external endometriosis, accounting for 80%, followed by the peritoneum of the rectouterine fossa, including the uterosacral ligament. The anterior wall of the rectouterine fossa is equivalent to the posterior vaginal fornix, and the posterior wall of the cervix is ​​equivalent to the internal os of the cervix. Sometimes the ectopic endometrium invades the anterior wall of the rectum, causing dense adhesions between the intestinal wall, the posterior wall of the uterus and the ovaries, which are difficult to separate during surgery. External endometriosis can also invade the recto-vaginal septum and form scattered black and purple dots on the mucosa of the posterior vaginal fornix, and even form cauliflower-like protrusions, which resemble cancer. Endometriosis can only be confirmed by biopsy. In addition, as mentioned above, the fallopian tubes, cervix, vulva, appendix, umbilicus, abdominal wall incision, hernia sac, bladder, lymph nodes, and even the pleura and pericardium, upper limbs, thighs, and skin may all have ectopic endometrium growth.

Ectopic endometrium in the rectouterine fossa may also form purple-black bleeding spots or blood cysts on the peritoneum, which are embedded in severely adherent fibrous tissue. Typical endometrium can be seen under microscopy. The ectopic endometrial tissue here can also extend to the rectovaginal septum and uterosacral ligament to form tender solid nodules, or penetrate the mucosa of the posterior vaginal fornix to form bluish-purple papillary masses. Many small bleeding spots may appear during menstruation. If the anterior wall of the rectum is affected, menstrual bowel pain may occur. Sometimes endometrial lesions extend around the rectum to form a narrow ring, which is very similar to a tumor. Intestinal invasion accounts for about 10% of endometriosis. Lesions are often located in the serosa and muscularis. Rarely is the mucosa invaded and ulcers occur. Occasionally, intestinal obstruction occurs due to the formation of masses in the intestinal wall or fibrous stenosis or adhesions that cause excessive bending of the intestine, and irritation symptoms may occur, such as intermittent diarrhea, which is more severe during menstruation.

The above is what the experts introduced to us about the causes of peritoneal endometriosis. I hope every friend can understand it. Since there are many causes of peritoneal endometriosis, everyone must further take effective precautions according to their own situation. For everyone's health, start with their usual eating habits, and their living habits also need to be normal, so that there can be a good treatment environment.