Share this article on:

Same-Day Synthetic Osmotic Dilators Compared With Overnight Laminaria Before Abortion at 14–18 Weeks of Gestation: A Randomized Controlled Trial

Newmann, Sara J. MD, MPH; Sokoloff, Abby MPH; Tharyil, Mithu MD; Illangasekare, Tushani MD; Steinauer, Jody E. MD, MSc; Drey, Eleanor A. MD, EdM

doi: 10.1097/AOG.0000000000000080
Contents: Original Research

OBJECTIVE: To increase access to early second-trimester surgical abortion by determining noninferiority of same-day synthetic osmotic dilators compared with overnight Laminaria for cervical preparation before early second-trimester dilation and evacuation.

METHODS: We enrolled women between 14 and 18 weeks of gestation and randomized them to same-day synthetic osmotic dilators or overnight Laminaria. Study participants and clinicians were blinded to group assignment. The primary outcome was procedure duration. The trial was powered to assess noninferiority of synthetic osmotic dilators to exclude a mean difference of 5 minutes or longer.

RESULTS: We enrolled 72 patients: 36 were randomized to same-day synthetic osmotic dilators and 36 to overnight Laminaria. Mean procedure duration was 8.1 and 5.9 minutes, respectively, with a mean difference of 2.1 minutes (97.5% confidence interval −0.3 to 4.5). Same-day synthetic osmotic dilators resulted in less initial cervical dilation than overnight Laminaria (mean circumference 48 compared with 60 mm Pratt, P<.001) and required more mechanical dilation (69% compared with 27%, P=.001). There was no difference in complications, all of which were minor, or in the median procedural difficulty score rated by physicians. Most patients in both groups would choose a same-day procedure if necessary in the future.

CONCLUSION: Despite less initial cervical dilation and a greater need for mechanical dilation, same-day synthetic osmotic dilators are not inferior to overnight Laminaria with respect to procedure duration. Same-day osmotic dilation is preferred by patients and may be a reasonable alternative to overnight Laminaria for cervical preparation before early second-trimester dilation and evacuation.



Same-day cervical preparation with synthetic osmotic dilators is not inferior to overnight preparation with Laminaria before early second-trimester surgical abortion with respect to procedure duration.

Bixby Center for Global Reproductive Health, Department of Obstetrics, Gynecology, and Reproductive Sciences, and the Department of Family and Community Medicine, University of California, San Francisco, San Francisco, California.

Corresponding author: Sara J. Newmann, MD, MPH, San Francisco General Hospital, 1001 Potrero Avenue, San Francisco, CA 94110; e-mail:

Supported by an anonymous foundation. Dr. Newmann was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI Grant Number KL2TR000143.

The authors thank Brian Jersky, PhD, for his statistical support and Phillip Darney, MD, MSc., for his guidance about study design.

The article contents are solely the responsibility of the authors and do not necessarily represent the official views of the funders.

Financial Disclosure The authors did not report any potential conflicts of interest.

© 2014 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.