Properties and safety of cervical dilators

Characteristics of cervical dilation produced by the new osmotic dilator, laminaria, and rigid (metal or plastic) dilators were compared. The osmotic dilator (Lamicel) is an open-porosity polyvinyl alcohol sponge loaded with magnesium sulfate and compressed into a rod. Pressures exerted by the Lamicel and laminaria tents were measured by placing them in a short elastic collar to simulate the cervical canal and allowing them to swell in water. At maximum dilation of the collar, the laminaria exerted 190 kPa (kPa = kilopascals; 6.895 kPa = 1 pound force/square inch), and the osmotic dilator, 14 kPa. The pressure that may be applied to the cervical canal with rigid dilators may be as much as 700 kPa. Because the Lamicel dilates the cervix passively and is as effective as laminaria, it appears to be the safest method of cervical dilation.