title: Temporal changes in cervical mucus after insertion of the levonorgestrel-releasing intrauterine system.
abstract: 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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Los Angeles County + University of Southern California Medical Center, Los Angeles, CA 90033, USA. natavio@usc.edu
authors.forename: Melissa F
authors.initials: MF
authors.lastname: Natavio
authors.forename: Deshawn
authors.initials: D
authors.lastname: Taylor
authors.forename: Radha A
authors.initials: RA
authors.lastname: Lewis
authors.forename: Paul
authors.initials: P
authors.lastname: Blumenthal
authors.forename: Juan C
authors.initials: JC
authors.lastname: Felix
authors.forename: Alexander
authors.initials: A
authors.lastname: Melamed
authors.forename: Elisabet
authors.initials: E
authors.lastname: Gentzschein
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Mishell
mesh_terms: D000328:Adult; D002582:Cervix Mucus / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D003271:Contraceptive Agents, Female / Q000008:administration & dosage* / Q000097:blood; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D007436:Intrauterine Devices, Medicated; D016912:Levonorgestrel / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D011374:Progesterone / Q000097:blood; D013083:Sperm Transport / Q000187:drug effects*; D013997:Time Factors; D055815:Young Adult
chemical_list: D003271:Contraceptive Agents, Female; D011374:Progesterone; D004958:Estradiol; D016912:Levonorgestrel