Levonorgestrel levels in serum and uterine flushings in women bearing LNG-Cu-IUD.

Radioimmunoassay was employed to measure levonorgestrel levels in serum and uterine flushings in women using intrauterine device releasing both copper ions and levonorgestrel (LNG-Cu-IUD) after one-year insertion. In the meanwhile physical characteristics of cervical mucus have been observed in women using LNG-Cu-IUD and compared with those using Tcu-220c-IUD. The mean concentrations of levonorgestrel in serum and uterine flushings (5 ml) were 84.53 pg/ml and 266.93 pg/ml respectively. In LNG-Cu-IUD group, the cervical mucus lacking in ferny crystals had a viscosity significantly higher than that in Tcu-220c-IUD group, suggesting that the local high concentration of levonorgestrel changed the environment of the uterine cavity and the cervical mucus status.