The Administration Time Point of Carboprost Methylate and Effects on Perioperative Complications and Cervical Ripening Effect in Artificial Abortion

Artificial abortion is the most widely used procedure in termination of first-trimester pregnancy. Cervical ripening before the operation guarantees operative convenience and decreases complications. An overstrained cervical dilation associates with uterine perforation, cervical laceration and cervical incompetence. To address the issue, various mechanical and pharmaceutical methods have been applied to prepare the cervix before transvaginal procedures. Prostaglandin analogues (PGs) play an important role in ripening the cervix or promoting uterine contraction in gynecology and obstetrics. As most tissues express prostaglandin receptors, vomiting, nausea, fever, diarrhea and abdominal pain can hardly be avoided with PGs administration. Longer PGs action contributes to better cervical ripening, but more uncomfortableness at the same time. These annoying symptoms may affect the participants' satisfaction and increase perioperative risks. To balance the safety and effectiveness of the surgery as well as patients' feeling, a proper timing for cervical ripening should be investigated. However, the administration timing of PGs has not reached a broad consensus, ranging from 16 hours to 2 hours before surgery. Carboprost methylate (CM), a PG-F2α analogue, has been used nationwide for cervical ripening in China. To minimize the side effects of PGs without affecting cervical ripening, the investigators intended to explore shortening the action time of CM in cervical preparation before artificial abortion. Thus, the investigators conducted this prospective cohort study and aimed to examine the efficacy of early and delayed vaginal administration of CM before surgery, and optimized both the perioperative safety and participants' convenience. The investigators hypothesize that early vaginal administration of CM would not affect the cervical ripening status, but will greatly reduce the unpleasant complications among the participants.