Haptoglobin expression by shed endometrial tissue fragments found in peritoneal fluid

OBJECTIVE: To confirm the endometrial glandular epithelial and stromal cells in tissue fragments recovered from peritoneal fluid and to quantify haptoglobin expression. DESIGN: Prospective, randomized study. SETTING: University of Missouri-Columbia School of Medicine and Health Care System. SUBJECT(S): Women undergoing laparoscopic surgery for diagnosis or treatment of endometriosis or for laparoscopic tubal cautery for desired sterilization. INTERVENTION(S): Aspiration of peritoneal fluid at laparoscopic surgery. MAIN OUTCOME MEASURE(S): Histological confirmation of endometrial glandular epithelial and stromal cells and evaluation of haptoglobin gene expression and protein localization in shed endometrial tissue fragments recovered from peritoneal fluid. RESULT(S): More visible tissue fragments were found in the peritoneal fluid from women with endometriosis (n = 28/65) than from that of women without endometriosis (n = 5/34). Of these tissues, endometrial glands and stroma were histologically confirmed in about half of women with endometriosis (n = 13/28) and without endometriosis (n = 3/5). Retrogradely shed endometrial tissues recovered from peritoneal fluid robustly express haptoglobin. CONCLUSION(S): Haptoglobin expression by retrogradely shed endometrial tissues in peritoneal fluid supports a mechanism whereby these purported precursors of endometriotic lesions escape immune destruction. Low recovery of histologically confirmed endometrial tissue fragments from peritoneal fluid reveals the potential difficulties for using these tissues for studies modeling the pathogenesis of endometriosis.