OPINION Transvaginal endoscopy and small ovarian endometriomas: unravelling the missing link?

Abstract The incidence of endometriosis in the infertile fe-male is estimated to be between 20 and 50 %. Although the causal relationship between endometriosis and infertility has not been proven, it is generally accepted that the disease impairs reproductive outcome. Indirect imaging techniques and transvaginal laparoscopy now offer the possibility of an early stage diagnosis. Although it remains debated whether the disease is progressive, treatment in an early stage is rec-ommendable as it carries less risk for ovarian damage, hence premature ovarian failure. Under water, inspection with the technique of transvaginal hydrolaparoscopy (THL) accurately shows the invagination of the ovarian cortex as minimal su-perficial lesions but with the presence of well-differentiated endometrial like tissue at the base, the lateral walls and espe-cially the inner edges of the small endometrioma. An inflam-matory environment is responsible for the formation of connecting adhesions with the broad ligament and lateral wall with invasion of endometrial-like tissue and forma-tion of adenomyotic lesions. In around 50 % of the small endometriomas, adhesiolysis is necessary at the site of invag-ination with opening of the cyst, to free the chocolate content and hereby recognize the underlying endometrioma. The de-tailed inspection of these early-stage endometriotic lesions at THL reunites the hypothesis of Sampson with the observation of Hughesdon