[Pearl index of the new Sof-T spiral in relation to ultrasound follow-up].

463 patients (109 nulliparae, 354 uni- and multiparae) were fitted with a new intrauterine device (IUD), Sof-T, and observed during 6,624 cycles. Two independent centres participated in the study. The T of Sof-T is made of flexible polyethylene, the two occlusion bodies, of medically approved silastic. If the Sof-T is correctly placed, they lie in the uterine horns. A copper wire of a total surface of 360 mm2 is winded around the vertical branch. The echogenicity of the occlusion bodies facilitates their visualization by ultrasound, thus improving the safety of the new Sof-T. The softness and the adaptability of these occlusion bodies to the cavity of the uterus decreased trauma, and thus hemorrhage and pain, compared to 16 other studies on IUDs. The small number of salpingitis recorded in our study of the Sof-T may be attributed to the fact that the pathogens transported and transmitted by sperm could probably not penetrate into the uterine tubes because they were stopped by the occlusion bodies.