Modern combined oral contraceptives for pain associated with endometriosis

Endometriosis is a major women's health-care problem. It causes pain and/or infertility, and affects millions of women worldwide. Endometriosis is defined according to histological criteria by the presence of tissue resembling endometrium in sites outside the uterus, most commonly the ovaries and peritoneum. The aim of treatment has been to remove the deposits of ectopic endometrium that are thought to be responsible for the symptoms of endometriosis. This can be achieved surgically by destroying or removing the implants; medical therapies induce atrophy within the hormonally-dependent ectopic endometrium. The duration of hormonal treatment may be limited by unwanted side effects. There is some evidence, however, from epidemiological research that current use of the combined oral contraceptive pill (OCP) is associated with a reduced incidence of endometriosis. The combined pill has the great advantage over other hormonal treatments that it can be taken indefinitely.

The aim of this review was to establish the role of modern oral contraceptives in the management of painful symptoms ascribed to endometriosis.

The search strategy of the Menstrual Disorders Group was utilised to identify all randomised trials of the use of oral contraceptives in the treatment of symptomatic endometriosis. In addition a search of the Cochrane Controlled Trials Register was undertaken together with approaches to pharmaceutical companies.

All truly randomised controlled trials of the use of oral contraceptive pills in the treatment of women of reproductive age with symptoms ascribed to the diagnosis of endometriosis made visually at a surgical procedure, were included.

Study quality assessment and data extraction was carried out independently by two reviewers. One of the assessors was an expert in the content matter.

Only one study was identified which satisfied the inclusion criteria. The oral contraceptive used in a conventional manner was less effective than a GnRH analogue in the relief of dysmenorrhoea. No significant difference was noted between the effectiveness of the oral contraceptive pill and a GnRH analogue in the relief of dyspareunia or non-menstrual pain. Headaches and weight gain were more commonly associated with oral contraceptive usage than with GnRH analogue usage whereas hot flushes, insomnia and vaginal dryness were less common.

There is a paucity of data relating to the use of oral contraceptive preparations in the treatment of symptomtic endometriosis. The data such as it is supports the common practice of the use of the oral contraceptive pill as a first line therapy but further research is required to fully evaluate its role in the management of endometriosis.