Same-day synthetic osmotic dilators compared with overnight laminaria before abortion at 14-18 weeks of gestation: a randomized controlled trial.

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. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, www.clinicaltrials.gov, NCT00775983. LEVEL OF EVIDENCE I.