Cervical dilation from laminaria tents and synthetic osmotic dilators used for 6 hours before abortion

Obstet Gynecol. 1995 Dec;86(6):931-5. doi: 10.1016/0029-7844(95)00325-L.


Objective: To compare thick laminaria tents with two synthetic osmotic devices for softening and dilating the cervix before abortions.

Methods: This was a randomized clinical trial comparing cervical dilation by thick laminaria tents with two commercially made devices, 3-mm Hypan and 3-mm anhydrous magnesium sulfate-impregnated plastic tents, used for 6 hours. Subjects were 7-14 weeks pregnant, and all 93 were assigned to devices in permuted randomized groups of three. Physicians and patients were not blinded to the type of device used. Need for a tenaculum for insertions, ease of introduction, cramps, removal ease, hourglassing, achieved dilation, and ease of forced dilation were compared. The effects of parity and gestational length on achieved dilation were also analyzed.

Results: Parity did not affect dilation. Significant positive, linear slopes of regression were found for achieved dilation versus weeks of gestation for thick laminaria tents and magnesium sulfate devices but not for Hypan tents. Forcible dilation was easiest with thick laminaria tents and most difficult with magnesium sulfate devices.

Conclusion: All devices provided safe cervical dilation and softening, but thick tents were most effective.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Abortion, Induced / methods*
  • Acrylic Resins*
  • Cervix Uteri / drug effects*
  • Female
  • Humans
  • Laminaria*
  • Osmosis
  • Polyvinyls*
  • Pregnancy
  • Pregnancy Trimester, First
  • Time Factors


  • Acrylic Resins
  • Polyvinyls
  • Hypan