The prevalence of endometriosis in unexplained infertility: a systematic review

In 15-30% of couples with infertility, no abnormalities are found after the initial diagnostic work-up. The aim of this study was to investigate the prevalence of endometriosis in patients with unexplained infertility undergoing diagnostic laparoscopy in the current era of improved imaging and assisted reproductive technology. A systematic search of PubMed, Embase and Cochrane Central was conducted to identify all studies reporting on pelvic pathologies found by laparoscopy in couples diagnosed with unexplained infertility. Normal ovulatory cycles, normal semen analysis and an infertility period of ≥12 months were the minimum requirements for a study population to be included. The prevalence of endometriosis was 44%, and most lesions were classified as minimal or mild (74%). The prevalence rates of tubal factors and adhesions were 20% and 16%, respectively. The detection rate for pelvic abnormalities was higher in women with prior fertility treatment (75%) compared with women without prior fertility treatment (53%). Despite the significant improvements in imaging for the diagnosis of endometriosis and tubal factors over the last decades, the prevalence rates of endometriosis and tubal abnormalities remain high in patients with unexplained infertility. The high prevalence of endometriosis in this population is important for decision-making in patients who also suffer from pain symptoms suggestive of endometriosis.