Do users of the intrauterine system (Mirena) have different genital symptoms and vaginal flora than users of the intrauterine contraceptive device?

The copper intrauterine contraceptive device (IUCD) is strongly associated with bacterial vaginosis (BV). Hormonal influences may play a role in the control of vaginal flora. It is unclear whether use of the progesterone-incorporated intrauterine system (IUS; Mirena) is associated with abnormal vaginal flora or genital symptoms. One hundred and seventy-two women were assessed for symptoms and abnormal vaginal flora prior to and at intervals after insertion of either a copper IUCD or an IUS. Women were significantly more likely to have developed an abnormal vaginal discharge 4-6 weeks after insertion of an IUCD compared with an IUS (27% cf. 14%, P = 0.04), although this trend was not significant six months postinsertion. More women with an IUCD developed BV compared with an IUS at 4-6 weeks and six months. However, there were insufficient numbers of women with BV to demonstrate any significant difference between the vaginal flora of the two groups.