Cyclooxygenase-2 expression in the endometrium and its relationship to bleeding in users of continuous oral contraceptives.

OBJECTIVE

The objective of the present study was to investigate whether or not the presence of irregular bleeding during use of oral contraceptives (OC) is associated with increased cyclooxygenase-2 (COX-2) expression.

METHODS

An observational study was carried out in 26 patients who were using gestodene 75 microg/ethinylestradiol 30 microg prior to endometrial resection. The patients were divided into two groups: those with amenorrhea (n = 14) and those who had irregular bleeding (n = 12). The resected endometrium was immunostained for COX-2, Bcl-2 and Ki-67 expression. Routine pathology was carried out using standard hematoxylin-eosin staining.

RESULTS

Irregular bleeding during OC use was associated with strong COX-2 expression in both glandular and superficial epithelium. There were also more patients in this group with irregular endometrial maturation and higher Ki-67 values. Bcl-2 expression, on the other hand, was not affected by the presence of uterine bleeding.

CONCLUSIONS

The presence of irregular bleeding during OC use is associated with strong COX-2 expression in the endometrium, thereby suggesting a pivotal role of prostaglandins in this process.