Seventeen systematic reviews published in The Cochrane Library were included. All the reviews were high quality. The quality of the evidence for specific comparisons ranged from very low to moderate. Limitations in the evidence included risk of bias in the primary studies, inconsistency between the studies, and imprecision in effect estimates.
Pain relief (14 reviews)
Gonadotrophin-releasing hormone (GnRH) analogues
One systematic review reported low quality evidence of an overall benefit for GnRH analogues compared with placebo or no treatment.
Five systematic reviews reported on medical treatment using ovulation suppression. There was moderate quality evidence that the levonorgestrel-releasing intrauterine system (LNG-IUD) was more effective than expectant management, and very low quality evidence that danazol was more effective than placebo. There was no consistent evidence of a difference in effectiveness between oral contraceptives and goserelin, estrogen plus progestogen and placebo, or progestogens and placebo, though in all cases the relevant evidence was of low or very low quality.
Non-steroidal anti-inflammatory drugs (NSAIDS)
A review of NSAIDs reported inconclusive evidence of a benefit in symptom relief compared with placebo.
There were two reviews of surgical interventions. One reported moderate quality evidence of a benefit in pain relief following laparoscopic surgery compared to diagnostic laparoscopy only. The other reported very low quality evidence that recurrence rates of endometriomata were lower after excisional surgery than after ablative surgery.
Post-surgical medical interventions
Two reviews reported on post-surgical medical interventions. Neither found evidence of an effect on pain outcomes, though in both cases the evidence was of low or very low quality.
There were two systematic reviews of alternative medicine. One reported evidence of a benefit from auricular acupuncture compared to Chinese herbal medicine, and the other reported no evidence of a difference between Chinese herbal medicine and danazol. In both cases the evidence was of low or very low quality.
One review found no evidence of a difference in effectiveness between anti-TNF-α drugs and placebo. However, the evidence was of low quality.
Reviews reporting fertility outcomes (8 reviews)
Four reviews reported on medical interventions for improving fertility in women with endometriosis. One compared three months of GnRH agonists with a control in women undergoing assisted reproduction and found very low quality evidence of an increase in clinical pregnancies in the treatment group. There was no evidence of a difference in effectiveness between the interventions in the other three reviews, which compared GnRH agonists versus antagonists, ovulation suppression versus placebo or no treatment, and pre-surgical medical therapy versus surgery alone. In all cases the evidence was of low or very low quality.
Three reviews reported on surgical interventions. There was moderate quality evidence that both live births or ongoing pregnancy rates and clinical pregnancy rates were higher after laparoscopic surgery than after diagnostic laparoscopy alone. There was low quality evidence of no difference in effectiveness between surgery and expectant management for endometrioma. One review found low quality evidence that excisional surgery resulted in higher clinical pregnancy rates than drainage or ablation of endometriomata.
Two reviews reported on post-surgical medical interventions. They found no evidence of an effect on clinical pregnancy rates. The evidence was of low or very low quality.
A review of Chinese herbal medicine in comparison with gestrinone found no evidence of a difference between the groups in clinical pregnancy rates. However, the evidence was of low quality.
Reviews of GnRH analogues and of danazol reported that the interventions were associated with higher rates of adverse effects than placebo; and depot progestagens were associated with higher rates of adverse events than other treatments. Chinese herbal medicine was associated with fewer side effects than gestrinone or danazol.
Three reviews reported miscarriage as an outcome. No difference was found between surgical and diagnostic laparoscopy, between GnRH agonists and antagonists, or between aspiration of endometrioma and expectant management. However, in all cases the quality of the evidence was of low quality.