Endometriosis and recurrent pregnancy loss.

A possible association between endometriosis and spontaneous abortion has been suggested in mostly uncontrolled and/or retrospective studies. Some controlled studies evaluating the association between endometriosis and spontaneous abortion showed important methodological shortcomings: heterogeneity between cases and controls, analysis of the abortion rate before the diagnosis of endometriosis, and selection bias of study and control groups. On the basis of controlled prospective studies, there is no evidence that endometriosis is associated with (recurrent) pregnancy loss or that medical or surgical treatment of endometriosis reduces the spontaneous abortion rate. In programs of assisted reproduction, some studies have shown that the number and quality of oocytes, the fertilization rate, and the implantation rate per embryo may be reduced in women with endometriosis, but this observation has not been confirmed by other investigators. Future studies evaluating the reproductive outcome of patients with endometriosis in assisted reproduction programs should include reliable information about the date and histological confirmation of the diagnosis of endometriosis, time interval between treatment with assisted reproduction and the last laparoscopy, possible recurrence of endometriosis, effectiveness of interim hormonal (suppressive) therapy, accuracy of ultrasound diagnosis, and accuracy of "negative" diagnosis.