Background
Cervical preparation prior to second trimester surgical abortion can reduce complications including hemorrhage and cervical laceration. Overnight osmotic dilators provide greater cervical dilation and may enable faster dilation and evacuation procedures than same-day cervical preparation. However, studies have consistently shown a strong patient preference for completing all abortion related procedures on the same day. Both misoprostol and synthetic osmotic dilators (Dilapan-S®) can be used for same-day cervical preparation prior to surgical abortion, with similar outcomes reported for 12-15 weeks gestational age. There are few studies with sufficient statistical power to adequately assess complications associated with same-day cervical preparation compared to overnight osmotic dilator placement.
             
Statement of Purpose
The purpose of our study is to confirm that same-day cervical preparation is associated with a comparable and clinically acceptable rate of complications compared to cervical preparation with overnight osmotic dilators. We will accomplish this through a retrospective review of electronic health records. We will compare complication rates between women who receive same-day cervical preparation, either with misoprostol or synthetic osmotic dilators or both, to women who receive overnight osmotic dilator placement at 14 to 16 weeks gestation. Our primary outcome will be the acute complication rate, or complications occurring within 24 hours of the abortion. Secondarily we will compare major complications, complications associated with same-day misoprostol versus same-day osmotic dilator placement and delayed complications occurring greater than 24 hours but less than 2 weeks from the abortion.
Basic Description of Methodology
This is a retrospective cohort study utilizing electronic health records. Our primary outcome is any acute complication occurring within 24 hours of a surgical abortion. Complications are defined as follows: any hospitalizations or hospital transfers, transfusions, or additional unplanned procedures. Additional unplanned procedures include: 1) uterine re-aspiration, 2) suture repair of a cervical laceration, 3) uterine tamponade with a Foley balloon or packing, 4) laparotomy or laparoscopy, 5) uterine artery embolization or 6) hysterectomy. Hemorrhage defined as EBL ≥ 500 cc or requiring treatment with three or more uterotonics will also be considered a complication. Heavy bleeding controlled with uterine massage, and/or one to two uterotonics, ferric subsulfate or pressure with a ring forcep (or equivalent) will not be included as a complication, whether uterine or cervical in origin. Of these, major complications are defined as any transfusion, uterine artery embolization, abdominal surgery, or hospital admission.
We have separately collected data on delayed complications as measured by patients who receive any unplanned abortion-related treatment within 2 weeks of the index procedure. However, because the quality of this data is limited, it will not be included in the primary analysis.
Data was collected from the Planned Parenthood League of Massachusetts electronic health record (EHR) from September 2010 to January 2016. A total of 1,319 charts were reviewed and will be included in the analysis. In our sample size calculation, we estimated a minimum of 598 patients (299 per arm) would be needed to determine if same-day cervical preparation is non-inferior to overnight osmotic dilator placement. Thus, we will have adequate statistical power to determine if same-day cervical preparation is associated with a clinically acceptable complication rate of no more than 10%.