Introduction
Background
Endometriosis is the presence of normal endometrial mucosa (glands and stroma) abnormally implanted in locations other than the uterine cavity. This tissue, possessing the same steroid receptors as normal endometrium, is capable of responding to the normal cyclic hormonal milieu. Microscopic internal bleeding, with the subsequent inflammatory response, neovascularization, and fibrosis formation, is responsible for the clinical consequences of this disease.
In the typical patient, the ectopic implants are located in the pelvis and manifest as severe dysmenorrhea, chronic pelvic pain, or infertility. More unusual implantation sites can be responsible for bizarre symptoms such as cyclic hemoptysis and catamenial seizures. The hormonal responsiveness of the implants can be exploited and provides the rationale for current methods of medical therapy.
Pathophysiology
Ectopic endometrial tissues are most commonly located in the dependent portions of the female pelvis (eg, posterior and anterior cul-de-sac, uterosacral ligaments, tubes, ovaries), but any organ system is potentially at risk.
These ectopic foci respond to cyclic hormonal fluctuations in much the same way as intrauterine endometrium, with proliferation, secretory activity, and cyclic sloughing of menstrual material. The products of this metabolic activity, including the concentrated and cyclic release of cytokines and prostaglandins, lead to an altered inflammatory response characterized by neovascularization and fibrosis formation. Some investigators have been able to demonstrate abnormal T- and B-cell function, abnormal complement deposition, and altered interleukin-6 production in women with this disease.
The associated pain, adhesion formation, and anatomic distortion are responsible for the clinical consequences of this disease.
Frequency
United States
The exact incidence in the general population is unknown because the definitive diagnosis requires biopsy or visualization of the endometriotic implants at laparoscopy or laparotomy. The best estimates of incidence in the general female population are 5-10%, and they come from women with proven fertility undergoing tubal sterilization procedures.
Incidence has been shown to be as high as 60% in women undergoing surgical evaluation for dysmenorrhea and 30% in women being evaluated for infertility. In a large series involving adolescent females with chronic pelvic pain, 45% were found to have endometriosis at laparoscopy. Of note, only 25% had a normal pelvis. In that series, the rate of endometriosis was found to increase with age from 12% in females aged 11-13 years to 45% in females aged 20-21 years.
International
A strong racial predilection does not appear to exist, and US rates should reflect those of the international community.
Mortality/Morbidity
Adolescent patients typically present with increasingly severe dysmenorrhea and/or chronic pelvic pain. Any persistent symptoms that seem cyclic in nature should prompt the practitioner to consider a search for endometriosis.
- Symptoms do not correlate well with disease severity. Significant dysfunction can be present with minimal gross disease, while severe endometriosis is sometimes asymptomatic.
- The pain of endometriosis responds poorly to antiprostaglandins and oral contraceptive pills.
- Symptoms are related to the site of endometriotic implants and the organ system involved.
Race
Previous studies suggesting increased rates in certain racial groups have not been supported by well-designed investigations. Strong racial predilection to endometriosis does not appear to exist.
Sex
Obviously, this is a disease largely confined to the female population. Interestingly, scattered case reports exist of lesions that are histologically indistinguishable from endometriosis found in men exposed to high-dose exogenous estrogens.
Age
Endometriosis is largely confined to women of reproductive age with an active hypothalamic-pituitary-ovarian axis.
- Prepubertal girls do not seem to be at risk for this disease, although the number of reports of endometriosis in young women shortly after menarche is increasing.
- Menopause (whether spontaneous or induced through surgical or medical means) usually leads to resolution of symptoms. The disease seems to remain quiescent even in the face of hormone replacement therapy.
Clinical
History
Symptoms of endometriosis can be variable but typically reflect the area of involvement. Because most endometriotic implants are found on the uterus, ovaries, and posterior peritoneum, the patient usually presents with a history of progressively increasing pelvic pain and/or secondary dysmenorrhea.
In contrast to primary dysmenorrhea, pain associated with endometriosis is minimally responsive to nonsteroidal anti-inflammatory drugs (NSAIDs) and cyclic oral contraceptive pills.
- Common elements in the history include nulliparity and regular though short menstrual cycles with prolonged flow of 8 or more days. Onset of pain usually precedes flow by a few days and begins to resolve 1-2 days into the menses. Patients who are sexually active may report deep dyspareunia that is worst in the premenstrual phase of the cycle.
- Not uncommonly, women report painful bowel movements, diarrhea, or even hematochezia in association with their menses when endometriosis involves the rectosigmoid colon. Likewise, dysuria, flank pain, or hematuria may be present if the bladder or ureters are involved.
- Occasionally, patients present with a cyclically painful expanding mass in a pelvic surgery scar. Excision reveals a focus of endometriosis.
- More uncommon cyclic symptoms include hemoptysis (pulmonary involvement), catamenial seizures (endometriotic lesions in the brain), and umbilical bleeding (implants in the umbilicus).
- Partial or complete bowel obstruction occasionally occurs because of either adhesion formation or a circumferential endometriosis lesion.
- When the products of cyclic sloughing of endometriotic implants become entrapped by cyst formation, the resulting mass is referred to as an endometrioma. These can occur in any location but are most commonly found involving one or both ovaries. These masses can become quite painful, and patients with rupture present with an acute surgical abdomen.
- A familial/genetic predisposition has been documented. A woman with a first-degree relative with endometriosis has a lifetime risk of the disease approximately 10 times that of a woman without an affected family member.
- In one large case series, the average onset of cyclic or noncyclic pain was 2.9 years after menarche.
Physical
- Patients with endometriosis do not frequently have any physical findings beyond tenderness related to the site of involvement.
- Findings suggestive of endometriosis include uterosacral ligament nodularity and tenderness, adnexal tenderness, and/or a tender adnexal mass.
Causes
- Early in the 20th century, Samson proposed his theory of retrograde menstruation as a cause of endometriosis. Subsequent studies have shown that retrograde menstruation is quite common and cannot adequately explain the extrauterine implantation of endometrial tissue. Nonetheless, conditions that increase the rate of retrograde menstruation, such as congenital outflow tract obstructions, do increase the risk of endometriosis.
- Other leading theories include metaplastic conversion of coelomic epithelium and hematogenous or lymphatic dispersion of endometrial cells. A combination of these explanations is required to explain all of the many clinical presentations of the disease.
- An altered immune response to the displaced endometrial tissue has been shown to play an important role as well.
- Intriguing nonhuman primate studies have demonstrated a strong association between dioxane exposure and the development of endometriosis, implying further that dysfunction of the immune system may contribute to this disease. Epidemiologic investigations have not been able to confirm this association in humans.
More on Endometriosis |
 Overview: Endometriosis |
| Differential Diagnoses & Workup: Endometriosis |
| Treatment & Medication: Endometriosis |
| Follow-up: Endometriosis |
| Multimedia: Endometriosis |
| References |
| Next Page » |
References
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Further Reading
Keywords
endometriosis, secondary dysmenorrhea, endometriosis externa, endometrioma
