RESUMEN
BACKGROUND: The major contraceptive action of the levonorgestrel-releasing intrauterine system (LNG-IUS) is cervical mucus (CM) thickening, which prevents sperm penetration. No study to date has examined the temporal relationship between the insertion of the LNG-IUS and changes in CM quality and sperm penetration. STUDY DESIGN: Participants were enrolled in a clinically descriptive study to compare the quality of CM and three parameters of sperm penetration prior to insertion of the LNG-IUS and on Days 1, 3 and 5 after insertion. Measurements of estradiol, progesterone and levonorgestrel (LNG) in serum and LNG in CM were also carried out at these times. CM was analyzed using the World Health Organization CM grading criteria. Sperm penetration was determined using an in vitro sperm-CM penetration test. RESULTS: All 10 participants underwent LNG-IUS insertion during midcycle when CM quality was good and sperm penetration was excellent. On Day 1 after LNG-IUS insertion, the majority of participants demonstrated poor CM quality and poor sperm penetration. On Day 3, all participants had poor CM quality, and all but one subject had poor sperm penetration. By Day 5, all participants had poor CM quality and poor sperm penetration. LNG levels in CM peaked on the day after LNG-IUS insertion. CONCLUSION: Significant changes in quality of CM and sperm penetration were observed shortly after LNG-IUS insertion; however, CM can remain penetrable for up to 5 days when the LNG-IUS is inserted midcycle.
Asunto(s)
Moco del Cuello Uterino/efectos de los fármacos , Anticonceptivos Femeninos/administración & dosificación , Dispositivos Intrauterinos Medicados , Levonorgestrel/administración & dosificación , Transporte Espermático/efectos de los fármacos , Adulto , Moco del Cuello Uterino/química , Moco del Cuello Uterino/metabolismo , Anticonceptivos Femeninos/sangre , Estradiol/sangre , Femenino , Humanos , Levonorgestrel/sangre , Masculino , Progesterona/sangre , Factores de Tiempo , Adulto JovenRESUMEN
BACKGROUND: In levonorgestrel intrauterine system (LNG-IUS) users, the prevention of sperm penetration through cervical mucus has not been demonstrated. STUDY DESIGN: Subjects were enrolled in an investigator-blinded study to compare quality and sperm penetrability of mid-cycle cervical mucus between LNG-IUS users and hormone-free controls. Cervical mucus was microscopically examined using World Health Organization (WHO) cervical mucus analysis (CMA). CMA score ≥10 of 15 points indicated cervical mucus favoring sperm penetration. Mucus was incubated with sperm using the WHO simplified slide test (SST) and Kremer sperm cervical mucus penetration test (SCMPT). RESULTS: Data from 14 LNG-IUS users and 16 controls showed 14% of LNG-IUS users had CMA score ≥10% vs. 69% of controls (p=.004). SST showed no sperm penetration for LNG-IUS users, significantly less than controls (0% vs. 64.3%, p<.001). SCMPT demonstrated no sperm mucus penetration for LNG-IUS users at 2 and 6 h (0% vs. 85% in controls with 2-h score ≥6, p<.001; 6 h 0% vs. 79% in controls, p<.001). CONCLUSIONS: Mid-cycle cervical mucus of LNG-IUS users is poor quality and prevents endocervical sperm transport in vitro.