Endometrial vascularization in levonorgestrel intrauterine device users; computerized microvessel measurement study.

Levonorgestrel use in the levonorgestrel intrauterine device (LNG-IUS) induces vascular distension within the superficial layer of the endometrium and massive pseudodecidualization. With a computer-assisted image analysis system, we objectively measured the vascular bed in LNG-IUS users and compared it to the physiological endometrium. A study was undertaken on 25 women using LNG-IUS, in an outpatient procedure at the time of removal of the IUS and compared with 11 normally cycling women (control group). Suction curette specimens were obtained just after retrieval of the IUS, and immunohistochemistry was carried out with a specific marker of the endothelial cells (CD31). Number of vessels decreased in the LNG-IUS group to 60/mm2 versus 124/mm2 in the control group, and mean vessel area increased to 1255 microm2 versus 157 microm2, respectively, in the control group. The decrease in mean vascular density and the increase of mean vessel area in the LNG-IUS group, compared to the control group, were both highly significant (p<.001).