evidence: Clinical guidelines. Cervical preparation for surgical abortion from 20 to 24 weeks' gestation - PMID: 18342657 - DOI: 10.1016/j.contraception.2008.01.004 Clinical guidelines. Cervical preparation for surgical abortion from 20 to 24 weeks' gestation Although less than 2% of abortions in the United States occur after 20 weeks, procedures performed at more advanced gestations are associated with increased morbidity and mortality. Adequate cervical preparation before dilation and evacuation (D&E) at 20 or more weeks' gestation reduces procedural risk. However, few clinical trials have included sufficient information on best practices for cervical preparation in this gestational age range. For procedures at 20 or more weeks' gestation, at least 1 day of cervical preparation is recommended. Evidence is less clear that the procedure is faster or safer with the use of either serial dilation over more than 1 day or adjuvant misoprostol. Osmotic dilators are preferable to misoprostol, but there are insufficient data to support either laminaria or Dilapan as the preferred dilator. Fewer Dilapan are needed to gain the same amount of dilation as laminaria. The Society of Family Planning recommends preoperative cervical preparation before D&E between 20 and 24 weeks. Further studies are needed to clarify the best means to prepare the cervix to minimize abortion complications and improve outcome in this gestational age range.