Induction and augmentation of labor: basis and methods for current practice.

Abstract

Medical control of labor is often necessary in modern obstetrics. The status of the cervix may dictate the method of induction and influence its success. Four milligrams of prostaglandin (PGE2) gel applied intravaginally has been shown to be a safe, efficacious, and extremely well-tolerated agent to promote cervical ripening. The patient should be monitored before and at least 4 hours after PGE2 gel application, since the incidence of uterine activity is high after this treatment and many of these pregnancies are at risk. The rare case of hyperstimulation may be treated with a tocolytic agent. The start of oxytocin may be individually tailored, but we do not recommend its use in less than 4 hours after gel insertion. Oxytocin should be used with great caution if the patient continues to have uterine activity from the PGE2 gel. Because, in part, the use of the PGE2 gel for cervical ripening is not approved by the Food and Drug Administration in the United States, it is prudent to discuss its use with the patient, document carefully, and use this medication only if there is clear indication. Protocols for the use of oxytocin currently used in many hospitals seem to be based on outdated pharmacologic data. Relatively new information on the pharmacology and clinical effects of oxytocin are reviewed to provide a rational approach to its clinical use in accordance with recently published guidelines from the American College of Obstetricians and Gynecologists (ACOG). The current data overwhelmingly indicate that oxytocin should be started at a low dose (0.5-1 mU/min) with a slow, arithmetical increase every 30 to 60 minutes. Previous reports of a high incidence of fetal distress, uterine dysfunction, and hyperstimulation in induced labor may be related to use of oxytocin at doses higher than currently appear appropriate. The risks of induction and augmentation can be reduced by careful patient selection and preparation. Oxytocin is safe and effective with expert medical management which provides careful monitoring, controlled infusion, persistence, and the knowledge of when to stop.