Vaginal administration of prostaglandin analogues as well as nitric oxide donors before first-trimester surgical abortion has been shown to induce effective cervical ripening. In addition, nitric oxide donors, such as isosorbide mononitrate and nitroglycerin, have been associated with a patient-friendly side-effect profile when administered 3 h before the surgical procedure. We wanted to compare the cervical ripening effect and possible side effects of isosorbide mononitrate and the prostaglandin analogue misoprostol when self-administered at bedtime the evening before surgical abortion.
