Changes in vascular basement membrane in the endometrium of Norplant users

Progestogen-only contraception is almost invariably associated with changes in menstrual bleeding patterns. Changes in the endometrial vasculature, and in particular an increase in vascular fragility, may contribute to this bleeding. In this study, endometrial vascular density and endothelial cell basement membrane components were examined using immunohistochemistry before and after insertion of Norplant(R), Endometrial vascular density was increased from a mean (+/- SEM) of 189.6 +/- 7.0 vessels/mm(2) during the control cycle to 253.9 +/- 80.7 vessels/mm(2) at 2-13 weeks of Norplant exposure, and to 212.7 +/- 12.9 vessels/mm(2) at 14-42 weeks. During the control cycle, a mean of 161.4 +/- 4.5 vessels/mm(2) stained for collagen IV (85% of all vessels), while at 2-13 weeks, 144.5 +/- 13.0 vessels/mm(2) stained for collagen IV (57% of all vessels) (t ratio = 2.08, P = 0.0057). By 14-42 weeks, 71% of vessels (151.0 +/- 9.8) vessels/mm(2) were surrounded by collagen IV. This was not significantly different from control values (t ratio = 2.03), Endometrial vascular laminin was also reduced following Norplant insertion, from a mean of 176.0 +/- 4.2 vessels/mm(2) in the control cycle (93% of vessels), to 156.3 +/- 6.7 vessels/mm(2) at 213 weeks of exposure (57% of vessels) (t ratio = 2.08, P = 0.01). By 14-42 weeks of exposure to Norplant, 162.5 +/- 9 vessels/mm(2) (76%) stained for laminin, This was not significantly different from control values (t ratio = 2.04). Endometrial vascular heparan sulphate proteoglycan (HSPG) was reduced from 58.6 +/- 3.0 vessels/ mm(2) during the control cycle (31% of vessels) to 43.6 +/- 5.6 vessels/mm(2) (only 17% of vessels) at 213 weeks (t ratio = 2.08, P = 0.025), At 14-42 weeks, only 19% of vessels stained for HSPG (41.3 +/- 5.8 vessels/mm(2); t ratio = 2.04, P = 0.009).