Clinical features of endometriosis
The placebo group of women in placebo-controlled trials provides some evidence of the natural history of the disease. Endometriosis can both deteriorate and improve spontaneously.
A placebo-controlled trial of danazol and medroxyprogesterone acetate1 (MPA) showed deterioration in 23% of those on placebo compared with none of the women on treatment. The disease improved in only 18% of women on placebo, compared with 60% of women on danazol and 63% of women on MPA. However, some of these women also had laparoscopic electrocoagulation initially, and therefore this is not a pure observation of the natural history of endometriosis.