Preparation of the cervix: hydrophilic and prostaglandin dilators.

The use of laminaria has made possible safe uterine evacuation in the second-trimester and has been identified as a protective factor in the prevention of uterine perforation in first-trimester abortion. Two additional approaches to cervical dilation are now available - synthetic hydrophilic dilators and prostaglandin analogues. Neither has been in use long enough to undergo thorough evaluation, but it seems possible that they may confer similar advantages while avoiding the discomfort and inconvenience associated with laminaria. New approaches to the use of laminaria have increased their value as cervical dilators. They may be left in the cervix for 6-48 hours. Multiple sets may be employed to achieve adequate cervical dilation for late second-trimester uterine evacuation. When fetal membranes are intact, prolonged use or multiple insertions of laminaria do not appear to increase rates of post-abortion infection. Lamicel and Dilapan are new synthetic dilators which affect the cervix much more rapidly than laminaria. The former does not apply radial force to the walls of the cervical canal, but the latter does. Significant dilation may be achieved in a few hours. Prostaglandins can also alter the cervix in only a few hours. Meteneprost appears to do so with minimal gastrointestinal side-effects and with a low risk of bleeding or abortion.