Was Sampson wrong?

Sampson's theory of reflux menstruation suggests that endometriosis is one form of a condition known as an autotransplant. This study seeks to characterize autotransplants as they are described in the literature and to determine whether endometriosis resembles an autotransplant.

Literature review of published studies containing the following types of information: [1] characterization of the histologic features, immunohistochemistry, or structural function of autotransplants; and [2] comparisons of endometriosis with endometrium.

Characteristics of multiple types of autotransplants were noted. Similarity or dissimilarity of endometriosis and endometrium was tabulated to judge qualitatively whether the bulk of the evidence supports the notion that endometriosis is an autotransplant.

Autotransplants remain very similar or identical to eutopic tissues of origin, regardless of the length of time following autotransplantation. Endometriosis differs in many profound and fundamental ways from eutopic endometrium, including clonality of origin, enzymatic activity, protein expression, and histologic and morphologic characteristics. A minority of studies has found similarities between endometriosis and eutopic endometrium.

Endometriosis is dissimilar to eutopic endometrium and therefore lacks characteristics of an autotransplant. Sampson's theory of origin of endometriosis is not supported by the results of this study. Studies of experimental endometriosis that have not used menstrual endometrium may be misleading.