Activation of NF-kappaB and COX-2 expression is associated with breakthrough bleeding in patients using oral contraceptives in extended regimens.

The objective of the present study was to determine whether there is an increase in endometrial inflammation associated with the occurrence of breakthrough bleeding in patients using an oral contraceptive in extended regimens. The presence of nuclear factor NF-kappaB and Cox-2 expression was determined by immunohistochemistry in endometrial samples removed by hysteroscopy from patients with breakthrough bleeding during continuous use of an oral contraceptive containing gestodene. All patients had a history of menorrhagia associated or not with the presence of uterine pathology. The percentage of endometria showing a positive staining reaction for NF-kappaB in cell nuclei was significantly higher in patients with breakthrough bleeding than in those with amenorrhea. Cox-2 expression in the endometrium was also significantly more frequent in patients with breakthrough bleeding. The occurrence of breakthrough bleeding in patients with uterine pathology using combined oral contraceptives is associated with the activation of endometrial inflammation through the NF-kappaB pathway.