In simple terms, endometriosis is a condition where endometrial-type tissue is found outside the uterus. It mainly affects fertile women and is more common in those who experience an early menarche or a later menopause. The disease is uncommon in teenagers who complain of dysmenorrhoea.
The aetiology of endometriosis is complex and partly due to retrograde menstruation. While this theory explains pelvic disease, other mechanisms are needed to explain endometrial deposition in distant sites, including immunological and embryological factors.
Extra-uterine endometrial tissue can occur anywhere, but most commonly within the pelvis and peritoneum. The bowel may also be affected, and cases have been described with ectopic endometrial tissue found in the lungs and even in the brain.
Deposits of endometrial tissue may be small and inconsequential, or large, causing significant morbidity, such as endometriomas (endometriotic cysts that affect the ovaries).
1. Variable presentations
Estimates of the proportion of women affected by endometriosis varies widely between 2 and 50 per cent. It may be asymptomatic, only causing minor problems, or debilitating.1
Presentation is variable and may include pelvic pain, dysmenorrhoea, deep dyspareunia, ovulatory pain, pain on defaecation, bowel or bladder symptoms including bleeding, and pain on micturition. Other presentations include fatigue, infertility, haemoptysis or even seizures.
The results of an examination in endometriosis are usually non-specific. A normal pelvic examination does not rule out the condition. Positive findings may include pelvic and utero-sacral ligament tenderness, a uterus fixed in retroversion, and palpable ovaries.
Guidelines from the Royal College of Obstetricians and Gynaecologists2 (RCOG) indicate that more specific evidence includes deeply infiltrating nodules that are palpable in either the pouch of Douglas or the uterosacral ligaments.
These nodules are most readily demonstrable during menstruation. Lesions may occasionally be visualised in the vagina or on the cervix.
2. Making the diagnosis
A diagnosis based on symptomatology and examination alone is difficult, and further investigations are often necessary.
This diagnostic difficulty often leads to a long delay in diagnosis, perhaps for many years.
The gold-standard test is laparoscopy,3 although findings on laparoscopy do not necessarily correlate well with the clinical picture. Laparoscopy should not be undertaken in younger women complaining of dysmenorrhoea without other supporting clinical evidence to suggest endometriosis.
Imaging techniques do not always provide useful evidence, although MRI can be helpful, and transvaginal ultrasound may enable disease affecting the bowel or bladder to be visualised.
Blood tests in the context of endometriosis may lead to confusion. CA125 levels, often used in the investigation of ovarian cancer, may be raised in endometriosis, but are of no diagnostic value in endometriosis.
Although the specificity is, perhaps counter-intuitively, around 90 per cent and the sensitivity increases with disease severity, the correlation is poor.
The treatment may involve either medical or surgical management, and psychosocial support is also of value.
The RCOG suggests it is reasonable to treat the patient empirically. Good evidence supporting the efficacy of NSAIDS is lacking, as with so many issues related to endometriosis.
However, the use of analgesia is intuitive and, for younger patients, should be the first line approach, usually in combination with a progesterone-only hormonal preparation or the combined contraceptive pill. Obviously, this approach should not be offered to women who wish to conceive.
The levonorgestrel intrauterine system (LNG-IUS) has been shown to reduce pain from endometriosis over three years. Other evidence for LNG-IUS shows that the number of women complaining of moderate to severe dysmenorrhoea was reduced from 45 to 10 per cent after having also received surgical treatment.
Rectal disease may also be improved. Other long-acting reversible contraceptives may also be used. If necessary, Gonadotrophin-releasing hormones analogues, with replacement estrogen and progesterone for bone mineral protection, are sometimes considered.
There is some also data on the benefits of aromatase inhibitors. More definitive treatment requires surgical intervention.
In addition to lesion ablation, ablation of the uterine nerve is sometimes performed. As disease recurrence is common, repeat laparoscopy after six months to remove residual disease has been shown to be an effective approach.
Surgical failure, which can be as high as 20 per cent, may be due to incomplete removal of disease, or even misdiagnosis.
4. Endometrial lesions
In many women, endometrial lesions resolve spontaneously. This makes assessment of treatment efficacy difficult. In cases where fertility is no longer required, hysterectomy and bilateral salpingo-oophorectomy may offer additional symptom relief.
The evidence of the effect of surgical treatment for infertility secondary to endometriosis is not conclusive, but in patients with endometriomas there is evidence of benefit from cystectomy rather than cyst drainage.
The five-year recurrence rate after treatment for endometriosis may be as high as 50 per cent, and patients should be warned of this outcome. With such a vast disease spectrum and with variable evidence surrounding treatment, careful and realistic handling of the patient's expectations are an essential part of management.
- Dr Thakkar is a GP in Wooburn Green, Buckinghamshire
1. Farquhar, F. Clinical review: endometriosis. BMJ 2007; 334: 249-53.
3. European Society of Human Reproduction and Embryology guideline for the diagnosis and treatment of endometriosis. www.endometriosis.org